Moderate varus/valgus malalignment after total knee arthroplasty has little effect on knee function or muscle strength: 91 patients assessed after 1 year

Background and purpose — Postoperative muscle strength and component alignment are important factors affecting functional results after total knee arthroplasty (TKA). We are not aware of any studies that have investigated the relationship between them. We therefore investigated whether coronal malalignment of the mechanical axis and/or of individual implant components would affect knee muscle strength and function 1 year after TKA surgery.Patients and methods — We included 120 consecutive osteoarthritis (OA) patients admitted for TKA. Preoperative active range of motion (ROM) of the knee, patient age, sex, and BMI were recorded and the Knee Society score (KSS) and knee joint extensor/flexor muscle strength were assessed. At 1-year follow-up, the mechanical and coronal component alignment was measured from a postoperative long standing radiograph, and ROM, KSS, and muscle strength measurements were taken in 91 patients. Functional outcome and muscle strength measurements were compared between normally aligned and malaligned TKA groups.Results — 29 of 91 TKAs were malaligned, i.e. they deviated more than 3° from the neutral mechanical axis. 18 femoral components and 15 tibial components were malaligned. Before surgery, the malaligned and normally aligned groups were similar regarding sex distribution, BMI, ROM, KSS, and muscle strength. At the 1-year follow-up, the differences between the groups regarding knee joint function and muscle strength were small, not statistically significant, and barely clinically relevant.Interpretation — Moderate varus/valgus malalignment of the mechanical axis or of individual components has no relevant clinical effect on function or muscle strength 1 year after TKA surgery.Failure to restore limb alignment in total knee arthroplasty (TKA) increases the risk of revision (Jeffery et al. 1991, Ritter et al. 1994 and 2011, Berend et al. 2004), but the effect of accurate postoperative alignment on TKA function is controversial (Lotke and Ecker 1977, Choong et al. 2009, Fang et al. 2009, Longstaff et al. 2009, Huang et al. 2012).Huang et al. (2012) reported that TKAs with a coronal alignment within 3° from the neutral axis had better function and quality of life at 5-year follow-up than TKAs that deviated more than 3° from neutral alignment. Other studies comparing computer-assisted TKA with conventional TKA surgery have not been able to correlate malalignment with inferior functional outcomes (Spencer et al. 2007, Kamat et al. 2009, Kim et al. 2009, Burnett and Barrack 2013).Patients with greater preoperative muscle strength have been reported to have faster recovery and better functional outcome after TKA (Mizner et al. 2005, Yoshida et al. 2008). However, full recovery of muscle strength after TKA is uncommon (Berth et al. 2002, Valtonen et al. 2009, Maffiuletti et al. 2010, Vahtrik et al. 2012).It is plausible that failure to restore the mechanical axis restoration results in inferior muscle function. Sogabe et al. (2009) found different cross-sectional areas in the quadriceps muscles with different knee alignments. They suggested that knees with varus or valgus deformation should have poorer muscle function compared to normally aligned knees. However, we have not been able find any studies investigating muscle strength after TKA in relation to component alignment and mechanical axis restoration.We investigated whether coronal malalignment of the mechanical axis and/or of individual implant components would affect knee muscle strength and function 1 year after TKA surgery.     

Osseointegrated total knee replacement connected to a lower limb prosthesis: 4 cases

Background and purpose — Osseointegrated implants are an alternative for prosthetic attachment in individuals with amputation who are unable to wear a socket. However, the load transmitted through the osseointegrated fixation to the residual tibia and knee joint can be unbearable for those with transtibial amputation and knee arthritis. We report on the feasibility of combining total knee replacement (TKR) with an osseointegrated implant for prosthetic attachment.Patients and methods — We retrospectively reviewed all 4 cases (aged 38–77 years) of transtibial amputations managed with osseointegration and TKR in 2012–2014. The below-the-knee prosthesis was connected to the tibial base plate of a TKR, enabling the tibial residuum and knee joint to act as weight-sharing structures. A 2-stage procedure involved connecting a standard hinged TKR to custom-made implants and creation of a skin-implant interface. Clinical outcomes were assessed at baseline and after 1–3 years of follow-up using standard measures of health-related quality of life, ambulation, and activity level including the questionnaire for transfemoral amputees (Q-TFA) and the 6-minute walk test.Results — There were no major complications, and there was 1 case of superficial infection. All patients showed improved clinical outcomes, with a Q-TFA improvement range of 29–52 and a 6-minute walk test improvement range of 37–84 meters.Interpretation — It is possible to combine TKR with osseointegrated implants.Socket-related discomfort leads to a significant reduction in the quality of life of individuals with lower limb amputation (Dillingham et al. 2001, Gholizadeh et al. 2014). Socket-skin interface problems lead to poor fit, diminished proprioception in the amputated limb, lack of rotational control, and reduction of ipsilateral proximal joint movement (Legro et al. 1999, Lyon et al. 2000, Meulenbelt et al. 2006).A direct connection of the prosthetic limb to the bone using osseointegrated implants can address these socket-related problems (Van de Meent et al. 2013, Tsikandylakis et al. 2014). Brånemark introduced this surgical procedure in 1995. He adapted osseointegration principles established in dental surgery to the rehabilitation of individuals with transfemoral amputation using a percutaneous bone anchoring implant screwed into the femur (Brånemark et al. 2001). Hip replacement spongiosa surface coating technology has been used to make a chrome cobalt intramedullary press-fit implant (Endo-Exo Prosthesis) allowing larger surface area for osseointegration and faster rehabilitation (Staubach and Grundei 2001). Al Muderis et al. (2015) adapted highly porous plasma-sprayed titanium implants to provide optimum initial press-fit and solid bone ingrowth.Studies of transfemoral implants have found improved quality of life, prosthetic use, body image, hip range of motion, sitting comfort, and walking ability (Van de Meent et al. 2013, Hagberg et al. 2014). For example, substantial improvements in health-related quality of life using the Global component of the questionnaire for transfemoral amputees (Q-TFA)—of 38 points (Hagberg et al. 2014) and 24 points (Van de Meent et al. 2013)—have been reported in 2 case series of 51 and 22 patients, respectively.Similar benefits could be expected for transtibial amputees using osseointegrated implants, as the knee joint could possibly enhance their gait. A study of 39 cases involving upper and lower limb prostheses (Tillander et al. 2010) found infections in 7 patients at an average follow-up period of 54 (3–132) months, with no infections reported for 1 tibial implant. At our own center, preliminary evidence of the safety and effectiveness of the tibial impants in 22 transtibial amputees with a minimum of 6 months of follow-up gave results consistent with the published results for transfemoral amputations (Khemka et al. 2015).Few authors have reported on the safety of this procedure (Brånemark et al. 2014, Tsikandylakis et al. 2014). One of the largest studies included 51 patients and reported superficial infections in approximately half of these patients at 2-year follow-up. In that study, the implant was removed in 1 patient due to deep infection and in 3 patients due to aseptic loosening (Brånemark et al. 2014).Osseointegrated implants are not currently recommended for transtibial amputees with ultra-short residuum. In addition to the practical technical challenges, biomechanical studies have suggested that small bone-implant contact is more likely to increase the risk of loosening (Lohr et al. 2000, Henriksen et al. 2003, Carvalho et al. 2012). Osseointegration is also not currently recommended for those suffering from ipsilateral knee osteoarthritis because it is hypothesized that an osseointegrated tibial implant will aggravate arthritic symptoms due to mechanical forces (Frossard et al. 2008).We describe the surgical procedure and early results of combining a total knee replacement (TKR) with an osseointegrated implant for prosthetic attachment for the first time.     

Changes in rates of arthroscopy due to degenerative knee disease and traumatic meniscal tears in Finland and Sweden

ResultsIn Finland, the annual number of operations was 16,389 in 1997, reached 20,432 in 2007, and declined to 15,018 in 2012. In Sweden, the number of operations was 9,944 in 2001, reached 11,711 in 2008, and declined to 8,114 in 2012. The knee arthroscopy incidence for OA was 124 per 10⁵ person-years in 2012 in Finland and it was 51 in Sweden. The incidence of knee arthroscopies for meniscal tears coded as traumatic steadily increased in Finland from 64 per 10⁵ person-years in 1997 to 97 per 10⁵ person-years in 2012, but not in Sweden.InterpretationThe incidence of arthroscopies for degenerative knee disease declined after 2008 in both countries. Remarkably, the incidence of arthroscopy for degenerative knee disease and traumatic meniscal tears is 2 to 4 times higher in Finland than in Sweden. Efficient implementation of new high-quality evidence in clinical practice could reduce the number of ineffective surgeries.Degenerative knee disease produces a variety of symptoms, clinical findings, and tissue abnormalities, eventually leading to knee osteoarthritis (OA). Nonoperative treatment of degenerative knee disease is recommended in guidelines, but arthroscopy is widely used (Kim et al. 2011, Nelson et al. 2014). Arthroscopic treatment includes debridement (lavage, smoothening, and removal of loose articular cartilage fragments), treatment of cartilage lesions, and resection of meniscal lesions (Felson 2010). Meniscal repair is preferred for acute traumatic tears of the meniscus (Sgaglione 2005). However, it is often difficult to distinguish between degenerative and traumatic meniscal tears. In older individuals and in patients with knee OA, meniscal tears are often degenerative and their prevalence increases with age (Curl et al. 1997, Metcalf and Barrett 2004, Englund et al. 2008). In younger patients, traumatic meniscal tears usually result from acute knee injury and are often associated with tears of the anterior cruciate ligament (Poehling et al. 1990).The practice of knee arthroscopy is in turmoil. In 2002, a pivotal randomized and placebo- (surgery) controlled trial found that arthroscopic debridement or lavage is no better than a sham procedure for treating knee OA (Moseley et al. 2002). This finding was later corroborated by Kirkley et al. (2008). This evidence led to recommendations to avoid knee arthroscopy procedures for patients with a primary diagnosis of knee OA (Conaghan et al. 2008, Richmond et al. 2009, Zhang et al. 2010). The recommendations, however, provided the option of knee arthroscopy in patients with signs and symptoms of a torn meniscus (Conaghan et al. 2008, Richmond et al. 2009) and for patients with low-grade OA (Zhang et al. 2010).Previous reports regarding the trends in a number of knee arthroscopic procedures indicate a reduced incidence of arthroscopies for knee OA, and a steady increase in the number of arthroscopic meniscus surgeries (Hawker et al. 2008, Kim et al. 2011, Abrams et al. 2013). In the UK, the incidence of arthroscopic meniscal resections more than doubled from 2000 to 2012 in patients over 60 years of age (Lazic et al. 2014). Similarly, in Denmark the number of meniscal procedures in patients aged 35 years or more increased during the period 2000–2011 (Thorlund et al. 2014).In this bi-national registry-based study involving the entire populations of Finland and Sweden, we assessed the numbers and incidence trends of arthroscopic knee procedures for degenerative knee disease and meniscal tears in Finland (between 1997 and 2012) and in Sweden (between 2001 and 2012).     

High tibial osteotomy in Sweden, 1998-2007: a population-based study of the use and rate of revision to knee arthroplasty

Background and purpose

Most studies on high tibial osteotomies (HTOs) have been hospital-based and have included a limited number of patients. We evaluated the use and outcome—expressed as rate of revision to knee arthroplasty—of HTO performed in Sweden with 9 million inhabitants, 1998–2007.

Patients and methods

3, 161 HTO procedures on patients 30 years or older (69% men) who were operated on for knee osteoarthritis in Sweden, 1998–2007, were identified through the inpatient and outpatient care registers of the Swedish National Board of Health and Welfare. Pertinent data were verified through surgical records. Conversions of HTO to knee arthroplasty before 2010 were identified through the Swedish Knee Arthroplasty Register (SKAR). The 10-year survival was determined using revision to an arthroplasty as the endpoint.

Results

The number of HTOs decreased by one third between 1998 and 2007, from 388 operations a year to 257 a year. Most of the HTOs were performed with open wedge osteotomy using external fixation. The cumulative revision rate at 10 years was 30% (95% CI: 28–32). The risk of revision increased with increasing age and was higher in women than in men (RR = 1.3, CI: 1.1–1.5).

Interpretation

If being without an artificial joint implant is considered to be beneficial, then HTO is an excellent alternative to knee arthroplasty in younger and/or physically active patients suffering from knee osteoarthritis.Among the surgical options for treatment of knee osteoarthritis (OA), high tibial osteotomy (HTO) is a joint-preserving alternative which is most commonly used in younger and/or physically active patients.HTO can be performed with different methods, such as closed wedge osteotomy, open wedge osteotomy, and dome-shaped osteotomy. It has been used as a surgical treatment for OA since the 1950s, and has served as a standard treatment for unicompartmental knee OA. However, the use of HTO has decreased during the last 3 decades, concomitant with increasing use of knee arthroplasty.At the beginning of the 1980s, HTO was estimated to constitute about 30% of the primary knee reconstruction surgery in Sweden (Tjörnstrand et al. 1981), decreasing to about 20% during the period 1989–1991 (Knutson et al. 1994). Information from the national database on inpatient procedures on the number of patients operated on by angle, rotation, or correction osteotomy in the knee or tibia from 1998–2007 showed a further decline by about 40% (W-Dahl et al. 2010a).Many follow-up studies on HTOs have reported good to excellent clinical results in the majority of patients with declining results over time and an increasing risk of revision after 10–15 years (Odenbring et al. 1990, Coventry et al. 1993, Naudie et al. 1999, Aglietti et al. 2003, Sprenger and Doerzbacher 2003, Koshino et al. 2004, Flecher et al. 2006, Papachristou et al. 2006, Akizuki et al. 2008, Gstottner et al. 2008, van Raaij et al. 2008, W-Dahl et al. 2010a, Schallberger et al. 2011). There have been very few publications involving more than 100 patients, and they have shown rates of revision at 10 years of between 5% and 20% (Odenbring et al. 1990, Flecher et al. 2006, Gstottner et al. 2008, W-Dahl et al. 2010a).In contrast to knee arthroplasties, we have found no national registrations of HTOs, and our knowledge of its use—including methods, techniques, patients, and outcome—is incomplete.In this study we investigated the use of HTO in Sweden during the period 1998–2007, and also the outcome expressed as rate of conversion to knee arthroplasty.     

Perioperative local infiltration anesthesia with ropivacaine has no effect on postoperative pain after total hip arthroplasty: A randomized,double-blind,placebo-controlled trial with 116 patients

Background and purpose — The local infiltration analgesia (LIA) technique has been widely used to reduce opioid requirements and to improve postoperative mobilization following total hip arthroplasty (THA). However, the evidence for the efficacy of LIA in THA is not yet clear. We determined whether single-shot LIA in addition to a multimodal analgesic regimen would reduce acute postoperative pain and opioid requirements after THA.Patients and methods — 116 patients undergoing primary THA under spinal anesthesia were included in this randomized, double-blind, placebo-controlled trial. All patients received oral opioid-sparing multimodal analgesia: etoricoxib, acetaminophen, and glucocorticoid. The patients were randomized to receive either 150 mL ropivacaine (2 mg/mL) and 0.5 mL epinephrine (1 mg/mL) or 150 mL 0.9% saline. Rescue analgesic consisted of morphine and oxycodone as needed. The primary endpoint was pain during mobilization in the recovery unit. Secondary endpoints were pain during mobilization on the day after surgery and total postoperative opioid requirements on the first postoperative day.Results — The levels of pain during mobilization—both in the recovery unit and on the day after surgery—and consumption of opioids on the first postoperative day were similar in the 2 groups.Interpretation — LIA did not provide any extra analgesic effect after THA over and above that from the multimodal analgesic regimen used in this study.Implementation of accelerated clinical pathways based on the fast-track principles reduces morbidity and enhances recovery for patients undergoing THA (Kehlet and Wilmore 2008). One of the key prerequisites is optimized pain relief, allowing early postoperative mobilization (Kehlet and Wilmore 2008). This requires that the pain treatment should be safe and effective, both at rest and during activity (Srikandarajah and Gilron 2011).The concept of multimodal analgesia for acute postoperative pain is to combine analgesics with additive or synergistic effects, which is meant to reduce the use of—and the adverse effects of—opioids and to allow early mobilization (Kehlet and Dahl 1993, Kehlet et al. 1999, Buvanendran and Kroin 2009). Multimodal analgesia in THA usually includes analgesics such as opioids, gabapentin, NSAIDs, acetaminophen, glucocorticoids, and local infiltration (Kardash et al. 2008, Kerr and Kohan 2008, Toms et al. 2008, Fredheim et al. 2011, Maund et al. 2011, Zhang et al. 2011).Kerr and Kohan (2008) reported reduced opioid requirements and reduced hospital stay with the use of LIA consisting of ropivacaine and NSAIDs. However, trials investigating the effect of ropivacaine in LIA have not determined whether ropivacaine alone gives similar improvements following THA (Lunn et al. 2011, Dobie et al. 2012, Zoric et al. 2014). Studies using LIA have often combined different analgesics (Kerr and Kohan 2008, Kuchalik et al. 2013), and this complicates interpretation of the results regarding the extent to which ropivacaine alone contributes to the outcome.Various studies have shown that LIA does not provide any additional analgesic benefit or reduce opioid consumption after THA (Lunn et al. 2011, Dobie et al. 2012, Solovyova et al. 2013, Zoric et al. 2014), and some authors do not recommend LIA in addition to a multimodal analgesic regimen after THA (Andersen et al. 2011, Lunn et al. 2011). Other studies have shown that LIA reduces the opioid consumption (Andersen et al. 2007, Kerr and Kohan 2008, Busch et al. 2010, Murphy et al. 2012, Kuchalik et al. 2013) and shortens the hospital stay after THA (Kerr and Kohan 2008, Scott et al. 2012) The results are thus conflicting, and the role of LIA in THA surgery still needs to be clarified.We investigated whether a single-shot LIA with ropivacaine in addition to a multimodal analgesic regimen would reduce acute postoperative pain and opioid requirements after THA.     

Muscular strength after total hip arthroplasty: A prospective comparison of 3 surgical approaches

ResultsDifferences in maximal strength change were greatest after 2 and 8 days. The posterior and anterior approaches produced less decrease in muscular strength than the direct lateral approach. 6 weeks postoperatively, the posterior approach produced greater increase in muscular strength than the direct lateral approach, and resulted in a greater increase in abduction strength than the anterior approach. At 3-month follow-up, no statistically significant differences between the groups were found. The operated legs were 18% weaker in leg press and 15% weaker in abduction than the unoperated legs, and the results were similar between groups.InterpretationThe posterior and anterior approaches appeared to have the least negative effect on abduction and leg press muscular strength in the first postoperative week; the posterior approach had the least negative effect, even up to 6 weeks postoperatively. THA patients have reduced muscle strength in the operated leg (compared to the unoperated leg) 3 months after surgery.Regaining muscular strength is important for postoperative function after hip arthroplasty. Inactivity reduces muscular strength and physical function (McGuire et al. 2001, Suesada et al. 2007, Kortebein et al. 2008), and muscular strength decreases substantially in the first week after total hip arthroplasty (THA) (Holm et al. 2013). Early recovery and rehabilitation of the weakened musculature is therefore of importance (Sicard-Rosenbaum et al. 2002). The type of surgical approach used has a major impact on THA stability and muscle function (Masonis and Bourne 2002).The direct lateral approach (DLA) is associated with a low dislocation risk (Witzleb et al. 2009), but of concern is that it traumatizes the abductor muscles, which can lead to permanent postoperative limp and weakness (Edmunds and Boscainos 2011). The posterior approach (PA) has been associated with postoperative dislocations (Edmunds and Boscainos 2011, Brooks 2013), mainly owing to the small femoral heads used to prevent wear (Bystrom et al. 2003). However, the introduction of highly cross-linked polyethylene into the articulation has reduced wear independently of head diameter (Bragdon et al. 2007), leading to increased use of larger head diameters (Lombardi et al. 2011). It has also been shown that a posterior soft-tissue repair following PA reduces the dislocation rate (van Stralen et al. 2003, Suh et al. 2004). The anterior approach (AA), first described by Robert Judet in 1947 as a modified Smith-Petersen approach, follows the principles of minimally invasive surgery. This approach provides intermuscular and internervous exposure to the hip (Wojciechowski et al. 2007), leading to reduced soft-tissue dissection and trauma (Bergin et al. 2011). Concerns have been related to higher complication rates owing to wound complications, intraoperative fracture, and compromised fixation after minimally invasive surgery, with increased risks of early revision surgery (Graw et al. 2010).There is no consensus on the relative functional advantages of different surgical approaches (Gulati et al. 2008, Edmunds and Boscainos 2011), and differences in maximal strength have not been examined. To our knowledge, there have been no studies comparing the DLA, the PA, and the AA in terms of early maximal muscular strength. We compared these 3 surgical approaches with regard to regaining of maximal muscular strength by 3 months postoperatively in patients undergoing THA.     

Metal-backed versus all-polyethylene tibial components in primary total knee arthroplasty

Background and purpose

The choice of either all-polyethylene (AP) tibial components or metal-backed (MB) tibial components in total knee arthroplasty (TKA) remains controversial. We therefore performed a meta-analysis and systematic review of randomized controlled trials that have evaluated MB and AP tibial components in primary TKA.

Methods

The search strategy included a computerized literature search (Medline, EMBASE, Scopus, and the Cochrane Central Register of Controlled Trials) and a manual search of major orthopedic journals. A meta-analysis and systematic review of randomized or quasi-randomized trials that compared the performance of tibial components in primary TKA was performed using a fixed or random effects model. We assessed the methodological quality of studies using Detsky quality scale.

Results

9 randomized controlled trials (RCTs) published between 2000 and 2009 met the inclusion quality standards for the systematic review. The mean standardized Detsky score was 14 (SD 3). We found that the frequency of radiolucent lines in the MB group was significantly higher than that in the AP group. There were no statistically significant differences between the MB and AP tibial components regarding component positioning, knee score, knee range of motion, quality of life, and postoperative complications.

Interpretation

Based on evidence obtained from this study, the AP tibial component was comparable with or better than the MB tibial component in TKA. However, high-quality RCTs are required to validate the results.The design of the tibial component is an important factor for implant failure in total knee arthroplasty (TKA) (Pagnano et al. 1999, Forster 2003, Gioe et al. 2007b, Willie et al. 2008, Garcia et al. 2009, KAT Trial Group 2009). The metal-backed (MB) design of tibial component has become predominant in TKA because it is thought to perform better than the all-polyethylene (AP) design (Muller et al. 2006, Gioe et al. 2006, 2007a,b). In theory, the MB tibial component reduces bending strains in the stem, reduces compressive stresses in the cement and cancellous bone beneath the baseplate (especially during asymmetric loading), and distributes load more evenly across the interface (Bartel et al. 1982, 1985, Taylor et al. 1998). However, critics of the MB tibial component claim that there are expensive implant costs, reduced polyethylene thickness with the same amount of bone resection, backside wear, and increased tensile stresses at the interface during eccentric loading (Bartel et al. 1982, 1985, Pomeroy et al. 2000, Rodriguez et al. 2001, Li et al. 2002, Muller et al. 2006, Blumenfeld and Scott 2010, Gioe and Maheshwari 2010).In the past decade, several randomized controlled trials (RCTs) have been performed to assess the effectiveness of the MB tibial component (Adalberth et al. 2000, 2001, Gioe and Bowman 2000, Norgren et al. 2004, Hyldahl et al. 2005a, b, Muller et al. 2006, Gioe et al. 2007, Bettinson et al. 2009, KAT Trial Group 2009). However, data have not been formally and systematically analyzed using quantitative methods in order to determine whether the MB tibial component is indeed optimal for patients in TKA. In this study, we wanted (1) to determine the scientific quality of published RCTs comparing the AP and MB tibial components in TKA using Detsky score (Detsky et al. 1992) and (2) to conduct a meta-analysis and systematic review of all published RCTs that have compared the effects of AP and MB tibial components on the radiographic and clinical outcomes of TKA.     

Local delivery of a selective androgen receptor modulator failed as an anabolic agent in a rat bone marrow ablation model

Background and purpose — Selective androgen receptor modulators (SARMs) have been developed to have systemic anabolic effects on bones and muscles without the adverse effects of steroidal androgens. One unexplored therapeutic option is the targeted application of SARMs for the enhancement of local new bone formation. We evaluated the osteogenic efficacy of a locally released SARM (ORM-11984).Methods — ORM-11984 was mixed with a copolymer of L-lactide and ɛ-caprolactone (PLCL). An in vitro dissolution test confirmed the sustainable release of ORM-11984 from the matrix. A bone marrow ablation model was used in female Sprague-Dawley rats. Implants containing 10%, 30%, or 50% ORM-11984 by weight or pure PLCL were inserted into the medullary canal of the ablated tibia. At 6 and 12 weeks, the volume of intramedullary new bone and the perimeter of bone-implant contact were measured by micro-computed tomography and histomorphometry.Results — Contrary to our hypothesis, there was a negative correlation between the amount of new bone around the implant and the dose of ORM-11984. There was only a mild (and not statistically significant) enhancement of bone formation in ablated bones subjected to the lowest dose of the SARM (10%).Interpretation — This study suggests that intramedullary/endosteal osteogenesis had a negative, dose-dependent response to locally released SARM. This result highlights the complexity of androgenic effects on bones and also suggests that there are biological limits to the targeted local application of SARMs.Male and female hormones, which act mainly via androgen receptors (ARs) and estrogen receptors (ERs), are physiological regulators of bone remodeling (Clarke and Khosla 2009, Vanderschueren et al. 2014). Drug development programs have successfully launched non-steroidal selective estrogen receptor modulators (SERMs) for various clinical indications, including postmenopausal osteoporosis (Komm and Mirkin 2014). The common goal of the corresponding programs for non-steroidal tissue-selective androgen receptor modulators (SARMs), which act as AR ligands, is to achieve systemic anabolic effects on bones and muscles without adverse androgenic effects (Mohler et al. 2009). Preclinical models have shown that the systemic administration of SARMs can protect the skeleton from the catabolic effects of orchiectomy and ovariectomy (Gao et al. 2005, Kearbey et al. 2007), partially restore the bone mass lost by ovariectomy (Kearbey et al. 2009), and enhance the therapeutic effects of anti-resorptive drug treatment (Vajda et al. 2009). The main clinical target of SARMs is aging populations with sarcopenia and bone frailty (Mohler et al. 2009), but no SARMs have yet reached the market.ARs are highly expressed in mature osteoblasts and osteocytes (Abu et al. 1997, Wiren et al. 2002), and androgens have been traditionally claimed to have direct anabolic bone effects. Data from studies on androgen-insensitive null mice with non-functional ARs (Yeh et al. 2002, Kawano et al. 2003, Venken et al. 2006, Sinnesael et al. 2012) and in mice that overexpress ARs (Wiren et al. 2004, 2008) have confirmed the physiological significance of AR-mediated bone remodeling processes. The androgenic action may be partly compartment-specific, and anabolic effects mainly appear at periosteal surfaces (Wiren et al. 2004, 2008, 2010, 2011), but several studies have clearly demonstrated that the lack of AR action results in general trabecular bone loss (Vanderschueren et al. 2014).Clinically, there are unmet needs for bone enhancement agents in elective reconstructive procedures and also in trauma surgery. One unexplored therapeutic option would be local application of SARMs as an anabolic bone agent. In this pilot study, the osteogenic efficacy of a SARM compound (ORM-11984) was tested in a rat bone marrow ablation model. Bone marrow ablation is a unique bone-healing model in which robust endosteal intramembranous bone formation is induced transiently by surgical ablation of the bone marrow (Suva et al. 1993). ARs are present in mesenchymal stromal stem cells of the bone marrow (Bellido et al. 1995), which are among the repair cells responsible for bone-healing processes (Bais et al. 2009). We hypothesized that the intramedullary administration of ORM-11984 would have androgenic anabolic effects on bone marrow-derived precursor cells and produce a dose-dependent enhancement of the local osteogenic response.     

The role of “cell therapy” in osteonecrosis of the femoral head: A systematic review of the literature and meta-analysis of 7 studies

ResultsThe pooled estimate of effect size for structural failure of the femoral head favored the cell therapy group, as, in this treatment group, the odds of progression of the femoral head to the collapse stage were reduced by a factor of 5 compared to the CD group (odds ratio (OR) = 0.2, 95% CI: 0.08–0.6; p = 0.02). The respective summarized estimate of effect size yielded halved odds for conversion to THR in the cell therapy group compared to CD group (OR = 0.6, 95% CI: 0.3–1.02; p = 0.06).InterpretationOur findings suggest that implantation of autologous mesenchymal stem cells (MSCs) into the core decompression track, particularly when employed at early (pre-collapse) stages of ONFH, would improve the survivorship of femoral heads and reduce the need for hip arthroplasty.Osteonecrosis of the femoral head (ONFH) is a progressive disease caused by a critical reduction in the blood supply to the femoral head and elevation of intraosseous pressure. Although its pathogenesis is poorly understood, it is generally accepted that various traumatic and non-traumatic insults compromise the already precarious circulation of the femoral head, leading to bone marrow and osteocyte death—and eventually collapse of the necrotic segment (Mont and Hungerford 1995). It mostly affects young adults, causing considerable morbidity (Slobogean et al. 2015). The annual incidence of ONFH in the USA is estimated to be 15,000–20,000 cases (Vail and Covington 1997). Most cases without any treatment progress to femoral head collapse and joint destruction, with total hip arthroplasty being the only treatment option (Lieberman et al., 2003). Magnetic resonance imaging (MRI) has contributed to early (pre-collapse) detection of the disease, providing an opportunity for timely intervention in order to avoid femoral head collapse and subsequent joint destruction.Various nonoperative and operative treatment modalities have been used to prevent—or at least delay—the progress of the disease towards femoral head collapse. Core decompression is a commonly used procedure, particularly in pre-collapse stages, but its effectiveness remains controversial (Ficat 1985, Learmonth et al. 1990, Markel et al. 1996, Saito et al. 1988, Yoon et al. 2001). Current research has focused on clarifying the molecular mechanisms involved in the pathogenesis of ONFH (Gangji and Hauzeur 2009, Kasten et al. 2008, Lee et al. 2009). Particular attention has been paid to multipotent mesenchymal stem cells (MSCs) and their ability to maintain mitotic multiplication while being capable of differentiating into various cellular types, such as osteoblasts, osteocytes, chondrocytes, and adipocytes (Baksh et al. 2004). Experimentally, MSCs have been shown to enhance tissue regeneration when transplanted in areas of necrotic bone (Yan et al. 2009). Various researchers have pioneered the clinical application of cell-based methods for the treatment of ONFH (Hernigou and Beaujean 2002, Gangji and Hauzeur 2005, Calori et al. 2014). Their technique was used in conjunction with the classical core decompression procedure and involved harvesting of autologous bone marrow aspirate, isolation of its mononuclear cell fraction, and injection of it into the necrotic zone of the femoral head through the canal of the preceding core decompression. This treatment strategy was based on the hypothesis that multiipotent MSCs in the bone marrow aspirate could repopulate the trabeculae of the necrotic zone within the femoral head, enhancing regeneration and remodeling of the necrotic bone (Hernigou et al. 2004).We performed a meta-analysis to investigate whether implantation of autologous bone marrow aspirate, containing MSCs, into the core decompression track would improve the clinical and radiological results of ONFH compared to the classical method of core decompression alone. The primary outcomes of interest were structural failure (collapse) of the femoral head and conversion to total hip replacement (THR).     

Better survival of hybrid total knee arthroplasty compared to cemented arthroplasty: A report from the Norwegian Arthroplasty Register 1999–2012

Background and purpose — There have been few comparative studies on total knee replacement (TKR) with cemented tibia and uncemented femur (hybrid TKR). Previous studies have not shown any difference in revision rate between cemented and hybrid fixation, but these studies had few hybrid prostheses. We have evaluated the outcome of hybrid TKR based on data from the Norwegian Arthroplasty Register (NAR).Patients and methods — We compared 4,585 hybrid TKRs to 20,095 cemented TKRs with risk of revision for any cause as the primary endpoint. We included primary TKRs without patella resurfacing that were reported to the NAR during the years 1999–2012. To minimize the possible confounding effect of prosthesis brands, only brands that were used both as hybrids and cemented in more than 200 cases were included. Kaplan-Meier survival analysis and Cox regression analysis were done with adjustment for age, sex, and preoperative diagnosis. To include death as a competing risk, cumulative incidence function estimates were calculated.Results — Estimated survival at 11 years was 94.3% (95% CI: 93.9–94.7) in the cemented TKR group and 96.3% (CI: 95.3–97.3) in the hybrid TKR group. The adjusted Cox regression analysis showed a lower risk of revision in the hybrid group (relative risk = 0.58, CI: 0.48–0.72, p < 0.001). The hybrid group included 3 brands of prostheses: LCS classic, LCS complete, and Profix. Profix hybrid TKR had lower risk of revision than cemented TKR, but the LCS classic and LCS complete did not. Kaplan-Meier estimated survival at 11 years was 96.8% (CI: 95.6–98.0) in the hybrid Profix group and 95.2% (CI: 94.6–95.8) in the cemented Profix group. Mean operating time was 17 min longer in the cemented group.Interpretation — Survivorship of the hybrid TKR at 11 years was better than that for cemented TKR, or the same, depending on the brand of prosthesis. Hybrid fixation appears to be a safe and time-efficient alternative to cemented fixation in total knee replacement surgery.Total knee joint replacement (TKR) is a highly successful operation with survival rates of more than 90% at 10 years (Carr et al. 2012). Only a few large comparative studies on different designs have been published (Knutson et al. 1986, Rand and Ilstrup 1991, Knutson et al. 1994, Robertsson 2000, Furnes et al. 2002, 2007, Sibanda et al. 2008). Most previous studies were not conclusive, due to their being too small or being biased with potential conflicts of interests (Carr et al. 2012). In the only meta-analysis on this topic, Nakama et al. (2012) found only 3 small randomized controlled studies that could be included for quantitative analysis. These authors were not able to make any conclusions about whether the prostheses should be cement-fixated, cementless, or hybrid.The fixation of primary TKRs has been extensively discussed, but no general agreement has been reached (Nakama et al. 2012). Cemented prostheses are regarded as the gold standard for TKR, supported by the long-term clinical success and survivorship analysis from registry-based and clinical studies (Robertsson 2000, Bellemans et al. 2005, Nakama et al. 2012). Cementless fixation is, however, still of interest to clinicians, who have used it in an attempt to reduce operation time, improve prosthetic durability, and preserve bone stock (Bassett 1998, Duffy et al. 1998, Nelissen et al. 1998, Regner 1998, Abu-Rajab et al. 2006).There have been few studies comparing the survival of different prosthesis brands and implant designs. A previous study from the Norwegian Arthroplasty Register (NAR) did not find any significant short-term differences at 5 years between the most commonly used brands in Norway (Furnes et al. 2002). The study did not show any significant differences in the overall revision rates between different fixation methods, but the number of hybrid prostheses was low, with only 739 knees (10%). The median follow-up time was short, number of prosthesis brands was high (7), and the power of the study was low regarding fixation method, due to low numbers of hybrid and cementless prostheses.In Sweden, almost all TKRs are cemented (SKAR, 2012). In Australia, there is more variation in fixation; more than 20% of TKRs have hybrid fixation (AOA 2012). In the report from 2011, for the first time hybrid fixation performed better than both cemented and cementless fixation at 10 years. Annual cumulative percent revision of primary TKR at 10 years was 5.6% (5.3–6.0) with cement fixation and 5.0 (4.6–5.3) with hybrid fixation (p = 0.02) (AOA 2012).There have been very few randomized prospective studies comparing primary TKRs using cemented fixation and primary TKRs using hydroxyapatite-coated, hybrid fixation. Most of them have compared uncemented fixation of the tibia and cemented fixation of the tibia. These studies have shown similar or inferior results for uncemented fixation (Nilsson et al. 1999, Regner et al. 2000, Carlsson et al. 2005, Beauprè et al. 2007). Short-term studies of hybrid fixation with cemented femur showed promising results (Faris et al. 2008). However, 1 medium-term report of 65 press-fit condylar arthroplasties had unacceptable implant survivorship and problems with the femoral component (Campbell et al. 1998).We compared the failure rates and mechanisms of failure of primary hybrid TKRs with those of primary cemented TKRs using the nationwide prospective observational register of knee implants in Norway.     

Which patients do not recover from shoulder impingement syndrome,either with operative treatment or with nonoperative treatment?: Subgroup analysis involving 140 patients at 2 and 5 years in a randomized study

Background and purpose — Shoulder impingement syndrome is common, but treatment is controversial. Arthroscopic acromioplasty is popular even though its efficacy is unknown. In this study, we analyzed stage-II shoulder impingement patients in subgroups to identify those who would benefit from the operation.Patients and methods — In a previous randomized study, 140 patients were either treated with a supervised exercise program or with arthroscopic acromioplasty followed by a similar exercise program. The patients were followed up at 2 and 5 years after randomization. Self-reported pain was used as the primary outcome measure.Results — Both treatment groups had less pain at 2 and 5 years, and this was similar in both groups. Duration of symptoms, marital status (single), long periods of sick leave, and lack of professional education appeared to increase the risk of persistent pain despite the treatment. Patients with impingement with radiological acromioclavicular (AC) joint degeneration also had more pain. The patients in the exercise group who later wanted operative treatment and had it did not get better after the operation.Interpretation — The natural course probably plays a substantial role in the outcome. Based on our findings, it is difficult to recommend arthroscopic acromioplasty for any specific subgroup. Regarding operative treatment, however, a concomitant AC joint resection might be recommended if there are signs of AC joint degeneration. Even more challenging for the development of a treatment algorithm is the finding that patients who do not recover after nonoperative treatment should not be operated either.Shoulder impingement syndrome has traditionally been divided into 3 progressive stages: (1) edema and hemorrhage (stage I), (2) fibrosis and tendinitis (stage II), and (3) tears of the rotator cuff, biceps ruptures, and bone changes (stage III) (Neer 1983). Nowadays, the term impingement syndrome is used to refer to a full range of rotator cuff abnormalities, being still a diagnosis based on physical examination (Papadonikolakis et al. 2011). Diercks et al. (2014) highlighted the need for a combination of clinical tests in the diagnosis, and suggested the use of an imaging test after prolonged symptoms (of more than 6 weeks) to rule out rotator cuff tears. Shoulder impingement is a common cause of shoulder pain (van der Windt et al. 1995, Urwin et al. 1998). Tendinopathy is considered to have a multifarious etiology: intrinsic mechanisms may be more important than extrinsic mechanisms (Factor and Dale 2014).Both nonoperative treatment and operative treatment have been used to treat this syndrome (Coghlan et al. 2008, Dorrestijn et al. 2009, Kromer et al. 2009, Chaudhury et al. 2010). It has been shown that arthroscopic acromioplasty is not superior to a supervised exercise program (Ketola et al. 2009, 2013, Papadonikolakis et al. 2011, Diercks et al. 2014, Saltychev et al. 2015). However, arthroscopic acromioplasty has been increasingly used during the last decade (Paloneva et al. 2015). Similar results have been obtained with open and arthroscopic acromioplasty (Davis et al. 2010). It is unclear whether a specific subgroup of patients who would benefit from arthroscopic acromioplasty can be identified. In most studies, the inclusion criterion has simply been failure of nonoperative treatment (Brox et al. 1999, Henkus et al. 2009). We have already done a cost-effectiveness study that suggested that arthroscopic acromioplasty followed by a structural exercise program is less cost-effective than exercise treatment alone (Ketola et al. 2009), and this was confirmed by Saltychev et al. (2015). We have now analyzed the 140 impingement patients from our previous study (Ketola et al. 2009) in subgroups to find out whether there is a subgroup of patients who would really benefit from arthroscopic acromioplasty. Secondly, we wanted to determine whether there is a subgroup in which the procedure should be avoided.     

PTH 1-34 (teriparatide) may not improve healing in proximal humerus fractures: A randomized,controlled study of 40 patients

Results39 patients completed the follow-up. The radiographic assessment showed a correct correlation, “better” in the teriparatide group and “normal” in the control group, in 21 of the 39 cases. There were no statistically significant differences in pain, in use of strong analgesics, or in function between the groups at the follow-up examinations.InterpretationThere were no radiographic signs of enhanced healing or improved clinical results in the group treated with teriparatideDuring the last 15 years, researchers have tried to improve fracture healing by using additional medication or growth factors such as bisphosphonates, bone morphogenetic proteins (BMPs), and parathyroid hormone (PTH). The hopes for improvement involved 2 different considerations, faster fracture healing and a reduced proportion of non-unions (Aspenberg 2013).Bisphosphonates, systemic or locally administered, have been shown to improve implant fixation, but their role in fracture treatment is unclear (Abtahi et al. 2012, Hilding and Aspenberg 2006, 2007). BMPs are thought to initiate fracture healing, but they have obvious side effects such as local swelling, pain, and increased risk of wound infections (Aro et al. 2011, Carragee et al. 2011). Studies sponsored by industry have obviously not reported the adverse effects associated with the administration of BMPs in spinal fusion (Carragee et al. 2011). There is also reason to believe that there is an increased risk of cancer after BMP treatment (Carragee et al. 2013).Animal studies have shown that there is accelerated fracture healing after intermittent injections with parathyroid hormone (PTH) (Skripitz and Aspenberg 2004, Chalidis et al. 2007). So far, only 3 papers have been published concerning PTH and fracture repair in humans. 2 papers with data from the same randomized trial involving distal radius fractures showed accelerated healing and improved callus formation (Aspenberg et al. 2010, Aspenberg and Johansson 2010). The radiological analysis showed minimal improvement in the position of the healed fracture, and there was no improvement in function. The third paper compared PTH 1-84 with placebo, and showed better healing in pubic bone fractures at 2 months in the treatment group, together with less pain and better walking ability (Peichl et al. 2011). However, that study had some methodological shortcomings. In conclusion, these studies have suggested that PTH may improve fracture healing in humans but the clinical importance for different diagnoses must be investigated and confirmed.The main aim of this study was to determine whether teriparatide enhances fracture healing of proximal humerus fractures, as evaluated on radiographs at 7 weeks. Secondary aims were to compare function, pain, and the use of opioid analgesics before the fracture, at 7 weeks, and after 3 months.     

More accurate component alignment in navigated total knee arthroplasty has no clinical benefit at 5-year follow-up

Background and purpose

Computer navigation in total knee arthroplasty is somewhat controversial. We have previously shown that femoral component positioning is more accurate with computed navigation than with conventional implantation techniques, but the clinical impact of this is unknown. We now report the 5-year outcome of our previously reported 2-year outcome study.

Methods

78 of initially 84 patients (80 of 86 knees) were clinically and radiographically reassessed 5 (5.1–5.9) years after conventional, image-based, and image-free total knee arthroplasty. The methodology was identical to that used preoperatively and at 2 years, including the Knee Society score (KSS) and the functional score (FS), and AP and true lateral standard radiographs.

Results

Although a more accurate femoral component positioning in the navigated groups was obtained, clinical outcome, number of reoperations, KSS, FS, and range of motion were similar between the groups.

Interpretation

The increased costs and time for navigated techniques did not translate into better functional and subjective medium-term outcome compared to conventional techniques.Abnormal wear patterns and component loosening are mainly results of component malalignment and complications of the extensor mechanism, the most common reasons for early failure of TKA (Ritter et al. 1994, Rand et al. 2003, Vince 2003, Bathis et al. 2004). It has been suggested that a varus or valgus malalignment of more the 3° leads to faster wear and debris, followed by early failure of TKA (Ecker et al. 1987, Archibeck and White 2003, Nizard et al. 2004).Several surgical navigation systems for TKA have been introduced to optimize component positioning (Delp et al. 1998, DiGioia et al. 1998, Krackow et al. 1999). It has been shown that navigation provides a more precise component positioning and fewer outliers (Bathis et al. 2004, Nabeyama et al. 2004, Stockl et al. 2004, Victor and Hoste 2004, Anderson et al. 2005, Zumstein et al. 2006). Nevertheless, comparing computer-navigated total knee arthroplasty with conventional implantation techniques, there is no evidence in the current literature of any significant improvement in clinical outcome and in component loosening (Bathis et al. 2004, Jenny et al. 2005, Yau et al. 2005, Bonutti et al. 2008, Molfetta and Caldo 2008).In a prospective study involving 86 patients in 3 different groups (image-based navigation, image-free navigation, and conventional), we showed that femoral component positioning was more accurate with navigation than with conventional implantation techniques, but tibial positioning showed similar results (Zumstein et al. 2006).Although other medium-term data on navigated total knee arthroplasty have already been reported (Ishida et al. 2011, Schmitt et al. 2011), there has been no prospective cohort series with reporting of the clinical, functional, and radiographic outcome with all 3 techniques: image-based navigated, image-free navigated, or conventional TKA. We therefore determined the clinical, functional, and radiographic 5-year results after each of the 3 techniques.     

Trochanteric stabilizing plate in the treatment of trochanteric fractures: a scoping review

Background and purpose — The trochanteric stabilizing plate (TSP) may be used as an adjunct to a sliding hip screw (SHS) in the treatment of trochanteric fractures to increase construct stability. We performed a scoping review of the literature to clarify when and how the TSP may be useful.Methods — A systematic search was performed in 5 databases and followed by a backwards-and-forwards citation search of the identified papers. 24 studies were included.Results — 6 biomechanical studies and 18 clinical studies were included in the review. The studies presented mainly low-level evidence. All studies were on unstable trochanteric fractures or fracture models. Due to the heterogeneity of methods and reporting, we were not able to perform a meta-analysis. In the biomechanical trials, the TSP appeared to increase stability compared with SHS alone, up to a level comparable with intramedullary nails (IMNs). We identified 1,091 clinical cases in the literature where a TSP had been used. There were 82 (8%) reoperations. The rate of complications and reoperations for SHS plus TSP was similar to previous reports on SHS alone and IMN. It was not possible to conclude whether the TSP gave better clinical results, when compared with either SHS alone or with IMN.Interpretation — The heterogeneity of methods and reporting precluded any clear recommendations on when to use the TSP, or if it should be used at all.

Internal fixation of trochanteric femoral fractures is usually performed with a plate or nail with a lag screw allowing axial compression to enhance fracture healing. The agreement between surgeons on implant choice is fair (Mellema et al. 2021). While a sliding hip screw (SHS) seems sufficient in stable trochanteric fractures (Parker and Handoll 2010), several guidelines recommend the use of intramedullary nails (IMNs) in more unstable fracture patterns (NICE 2011, Roberts and Brox 2015). Fixation without a lag screw is not recommended (Parker and Handoll 2010, Parker et al. 2018). Fractures involving the lateral wall, or with posteromedial comminution, are considered as unstable. This might cause excessive medialization of the femoral shaft, malunion, poor functional results, and even fixation failure (Parker 1996, Bretherton and Parker 2016). In addition, a thin lateral wall or a concomitant fracture through the greater trochanter increases the risk for an intra- or postoperative lateral wall fracture (Palm et al. 2007, Hsu et al. 2013). Under these circumstances, with a compromised lateral buttress, implant-preventing secondary displacement is required.The trochanteric stabilizing plate (TSP) was introduced in the early 1990s as an adjunct to the sliding hip screw. The plate acts by buttressing the lateral trochanteric wall and is intended to prevent medialization of the femoral shaft (Figure 1). Despite being sparsely discussed in the literature, an SHS with an additional TSP has been widely used in some countries and regions for decades (Lunsjö et al. 2001, Bong et al. 2004, Gupta et al. 2010, Knobe et al. 2013, Hsu et al. 2015, Alm et al. 2021). We reviewed the literature on TSP to clarify existing evidence and aid in the decision-making on when to use a TSP.Open in a separate windowFigure 1.Pre- and postoperative images of a AO/OTA 31-A2 fracture operated on with a sliding hip screw with trochanteric stabilizing plate (TSP). The TSP should prevent excessive medialization of the femoral shaft by buttressing the lateral trochanteric wall. In this case, a loss of medial buttress with a large lesser trochanter fragment and a thin lateral wall would strengthen the traditional indication for a TSP.     

Effect of rotational alignment on outcome of total knee arthroplasty: A systematic review of the literature and correlation analysis

Background and purpose

Poor outcomes have been linked to errors in rotational alignment of total knee arthroplasty components. The aims of this study were to determine the correlation between rotational alignment and outcome, to review the success of revision for malrotated total knee arthroplasty, and to determine whether evidence-based guidelines for malrotated total knee arthroplasty can be proposed.

Patients and methods

We conducted a systematic review including all studies reporting on both rotational alignment and functional outcome. Comparable studies were used in a correlation analysis and results of revision were analyzed separately.

Results

846 studies were identified, 25 of which met the inclusion criteria. From this selection, 11 studies could be included in the correlation analysis. A medium positive correlation (ρ = 0.44, 95% CI: 0.27–0.59) and a large positive correlation (ρ = 0.68, 95% CI: 0.64–0.73) were found between external rotation of the tibial component and the femoral component, respectively, and the Knee Society score. Revision for malrotation gave positive results in all 6 studies in this field.

Interpretation

Medium and large positive correlations were found between tibial and femoral component rotational alignment on the one hand and better functional outcome on the other. Revision of malrotated total knee arthroplasty may be successful. However, a clear cutoff point for revision for malrotated total knee arthroplasty components could not be identified.About 1 in 5 TKA patients are dissatisfied with the outcome (Bourne et al. 2010). A systematic review by the European Arthroplasty Register reported the results of 6 national joint registry datasets. A combined revision rate of 1.3 revisions per 100 observed component years after primary TKA was reported, and revision rates of about 6% after 5 years and 12% after 10 years are to be expected (Labek et al. 2011). Many possible causes of painful or malfunctioning TKAs have been defined, but the true cause often remains unknown (Thornhill 2002, Dennis 2004, Toms et al. 2009). Rotational errors of TKA components are frequently overlooked as the origin of problems, which can lead to unnecessary procedures (Bedard et al. 2011). Poor outcomes and major complications—e.g. patellofemoral pain, instability, and stiffness after TKA—have been linked to errors in rotational alignment of the components (Mochizuki and Schurman 1979, Rhoads et al. 1990, Berger et al. 1998, Miller et al. 2001, Sikorski 2008). Thus, the aims of the present study were (1) to examine the correlation between rotational alignment of the TKA component and outcome, (2) to review the results of revision operations for rotational malaligned TKA, and (3) to investigate whether practical recommendations can be made to guide treatment of a rotational malaligned TKA.     

Computed tomography scanogram compared to long leg radiograph for determining axial knee alignment

Background and purpose

Supine computed tomography scanogram (CTS) is a commonly used alternative to weight bearing long leg plain radiograph (LLR) in measuring knee alignment. No published studies have validated its use in the native knee and the post-unicompartmental replacement knee (UKR). We quantified the difference in measurements obtained from CTS and LLR for knee alignment.

Patients and methods

Supine CT scanograms and weight bearing long leg plain anteroposterior radiographs were obtained for 40 knees (in 25 patients), 17 of which were native, and 23 of which were post-UKR. The mechanical and anatomical axes of the tibio-femoral joint were measured. Bland-Altman plots were used to calculate the 1.96 standard deviation limits of agreement between CTS and LLR. Intraclass correlation was used to assess intra-rater and inter-rater reliability (where values > 0.81 indicate very good reliability).

Results

CTS and LLR were equally reliable in measurement of the mechanical and anatomical axes of the tibio-femoral joint (intraclass correlation coefficient (ICC) > 0.9 for all parameters). Statistically significant and clinically relevant differences were found between CTS and LLR in measurement of the mechanical axis (limits of agreement: UKR −3.2° to 6.3°; native −3.2° to 5.6°) and the anatomical axis (limits of agreement: UKR −3.7° to 8.7°; native −2.0° to 8.8°).

Interpretation

Although it is a reliable tool, CTS is not necessarily an accurate one for measurement of knee alignment when compared to LLR. We recommend that CTS should not be used as a substitute for LLR in measurement of the mechanical or anatomical axes of the knee.Measurement of knee alignment is useful in planning of operative intervention including high tibial osteotomy (HTO), uncompartmental knee replacement (UKR), and total knee replacement (TKR), and in the assessment of postoperative outcomes (Hernigou and Deschamps 2004, Hardeman et al. 2012, Kyung et al. 2013, Pietsch et al. 2013, Chen et al. 2014). The degree of accuracy required is thought to be ± 5° for native knees (Sharma et al. 2011), ± 3° after TKR (Bathis et al. 2004), and ± 2.5° after UKR (Gulati et al. 2009, Weale et al. 2000).The weight bearing long leg anteroposterior radiograph (LLR) shows loss of cartilage space and ligament laxity, and is therefore thought to be the best method for the measurement of coronal alignment of the knee (Babazadeh et al. 2013). However, some feel that the supine LLR is more suitable for planning in HTO (Ogata et al. 1991, Brouwer et al. 2003).Several recent papers have used the 2-D supine CT scanogram/scout film (CTS) to assess knee alignment (Moon et al. 2012, Kyung et al. 2013, Bugbee et al. 2013). Clinicians are also using this modality in clinical practice. CTS is severely limited by being a non-weight bearing modality in addition to having the same limitations as LLR (i.e. influence of rotational malalignment and flexion deformity). Brouwer et al. (2003) compared standing and supine LLR, but patients were excluded if they were unable to stand on one leg, if they had had previous surgery, or if they had a clinical malalignment. Gbejuade et al. (2014) compared CTS and LLR after TKR; however, weight bearing may not be as important a factor in measurement of alignment after TKR.The present study is the first to determine the differences in knee alignment measurement between CTS and LLR in native knees and after UKR.