Unicondylar knee arthroplasty in the UK National Health Service: An analysis of candidacy, outcome and cost efficacy

The viability of unicondylar knee arthroplasty (UKA) as a stand-alone or temporising option for the management of gonarthrosis is a topic of considerable contention. Despite recent advances in prosthesis design and surgical technique, as well as mounting evidence of long-term survivorship, UKA remains infrequently used, accounting for just 8–15% of all knee arthroplasties. Instead this group is more typically managed using total knee arthroplasty (TKA). For UKA to warrant increased usage the candidacy for UKA must be prevalent, the outcome must be equivalent or superior to that of TKA, and the costs should be comparatively low. Here we address three issues regarding UKA: 1) a prospective assessment of the proportion of knees needing arthroplasty that are candidates for UKA; 2) retrospective outcome measures comparing TKA, UKA and controls; and 3) an estimation of the difference in costs between TKA and UKA from a hospital perspective. We show in a series of 200 knees that candidacy for UKA is widespread; representing 47.6% of knees. Furthermore, we also show for the first time, that not only is UKA functionally superior to TKA (based on Total Knee Questionnaire (TKQ) scores), but scores in medial and lateral UKA knees do not differ significantly from normal, non-operative age- and sex-matched knees (t = 1.14 [38], p = 0.163; and t = 1.16 [38], p = 0.255 respectively). Finally, we report that UKA offers a substantial cost saving over TKA (£1761 per knee) indicating that UKA should be considered the primary treatment option for unicompartmental knee arthritis.     

Conversion total knee arthroplasty: A case complexity between primary and revision total knee arthroplasty

BackgroundConversion total knee arthroplasty (TKA) may represent a more complex procedure compared with primary TKA. The purpose of this study was to compare 30-day complications between conversion TKA and primary, non-conversion TKA as well as between conversion TKA and revision TKA on a national scale using a multi-center surgical registry.MethodsAdult patients undergoing conversion TKA from 2006 to 2018 were identified in the National Surgical Quality Improvement Program database and were compared with patients who underwent primary TKA and aseptic revision TKA. In this analysis, 30-day complications were assessed. Bivariate analyses, including chi-squared and analysis of variance, and multivariate logistic regressions were performed.ResultsOf 299,065 total patients undergoing knee arthroplasty, 1,310 (0.4%) underwent conversion TKA, 275,470 (92.1%) underwent primary TKA, and 22,285 (7.5%) underwent revision TKA. Following adjustment, patients who underwent conversion TKA were more likely to have increased risks of any complications (P < 0.001), mortality (P = 0.021), wound complications (P < 0.001), cardiac issues (P = 0.018), bleeding requiring transfusion (P < 0.001), and reoperation (P = 0.002) relative to primary TKA patients. Compared with patients who underwent revision TKA, conversion TKA patients were less likely to have septic complications (P = 0.009).ConclusionConversion TKA is associated with significantly higher rates of complications compared with primary, non-conversion TKA, but less risk of sepsis compared with revision TKA. Because current reimbursement classifications do not account for the case complexity of a conversion TKA, new classifications should be implemented with reimbursements for conversion TKA approximating reimbursements for revision TKA.     

Prospective sequential comparison of femoral roll-back between cruciate-retaining and posterior-stabilized total knee arthroplasty using an intra-operative sensor

BackgroundImplant design and surgical techniques affect postoperative knee kinematics in total knee arthroplasty (TKA). This study aimed to compare femoral roll-back between cruciate-retaining (CR) and posterior-stabilized (PS) TKA in the same knee by objectively quantifying the contact point kinematics of the tibiofemoral joint using a sensor.MethodsIn the present prospective study, we used an intraoperative sensor to compare medial and lateral roll-back during 0-120° knee flexion in 33 knees that underwent CR and PS TKA. We also examined the relationship between mediolateral balance and the lateral-to-medial roll-back ratio. We defined the contact percentage position as the vertical length to the contact point divided by the anteroposterior length of the tibial plate.ResultsThe roll-back percentage following PS TKA (19.8 ± 5.1%) was significantly higher than that after CR TKA in both the medial (19.8 ± 5.1% versus 7.1 ± 2.5%, P < 0.001) and lateral (26.8% ± 3.8% versus 18.7 ± 3.8%, P < 0.001) compartments. The medial contact pressure at 90° was significantly correlated with the increased lateral-to-medial roll-back ratio in both CR and PS TKA (both P < 0.001).ConclusionPS TKA resulted in a higher percentage of femoral roll-back in the medial and lateral compartments than CR TKA. CR TKA caused a higher lateral-to-medial roll-back ratio compared to PS TKA. To reproduce medial pivot knee motion similar to that of a normal knee, the medial soft tissue needed to be balanced more tightly than the lateral soft tissue during TKA. These findings provide some clinical evidence of TKA design selection and proper mediolateral balancing for successful TKA.     

Radiographic severity,extent and pattern of cartilage loss are not associated with patient reported outcomes before or after total knee arthroplasty in end-stage knee osteoarthritis

BackgroundThe aim of this study was to determine if radiographic severity, extent or pattern of knee osteoarthritis was associated with pain and function before total knee arthroplasty (TKA) or improvement therein one year after TKA.MethodsA prospective study of 259 patients undergoing unilateral TKA for Kellgren-Lawrence (KL) grade ≥ 3 knee osteoarthritis was conducted: mean age 69.8 ± 9.7 (44–91); mean BMI 31.0 ± 5.8 (17–52); 152/259 (58.7%) female. Preoperative radiographs were assessed using the KL and Ahlback systems. Preoperatively and 1 year postoperatively patients completed Oxford Knee Scores, VAS-Pain and EQ-5D scores. Full thickness cartilage loss was recorded intraoperatively.ResultsMedian radiographic severity was Ahlback 2, KL 4: 51/259 (19.7%) hypertrophic; 23/259 (8.8%) atrophic. Neither Ahlback nor Kellgren-Lawrence OA grade was associated with OKS, VAS Pain or EQ-5D prior to TKA (p > 0.05). The extent and pattern of cartilage loss did not affect preoperative PROMs. Radiographic OA severity, compartment involvement, and pattern of cartilage loss were not significantly associated with PROMs or improvements therein following TKA (p > 0.05). Hypertrophic OA was associated with less pain before TKA (difference 6.8, 0.23–13.9 95%CI, p = 0.044), and worse improvement in OKS following TKA (difference −3.41, −6.8 to −0.05 95%CI, p = 0.047). Better preoperative OKS and hypertrophic OA were independently associated with poorer improvement in OKS 1 year following TKA (R² = 0.208).ConclusionProvided at least one compartment has KL grade ≥ 3 changes, further radiographic severity, pattern or extent of cartilage loss did not affect PROMs before or after TKA: multicompartmental was no worse than unicompartmental disease.     

Short-term results of triathlon cementless versus cemented primary total knee arthroplasty

BackgroundRecent studies have demonstrated that aseptic loosening remains a leading cause of failure after total knee arthroplasty (TKA). Cementless fixation is a possible strategy for countering this problem. This study compared short-term survivorship and functional results of patients undergoing primary TKA with cementless versus cemented implants.MethodsA multi-center database was utilized to identify 3849 patients undergoing primary TKA between 2012 and 2017 with a minimum two-year follow-up. Patients were divided into cementless (699), and cemented TKA (3150). The outcome of TKA including revision for aseptic or septic reasons, and other outcome variables were compared. Six hundred five patients from the cementless group (case) were matched with 605 patients from the cemented group (controls). Both groups were compared for outcomes and related variables.ResultsBoth matched groups were similar in age, race, gender, height, weight, BMI, laterality, femoral component type, follow-up duration, preoperative and postoperative physical and mental health, and functional activities (all p-values >0.05). Although the cementless TKA group had more components in varus alignment (p = 0.015) and were taller (p < 0.001), the aseptic revision rate and time to failure were similar in both groups (p-values = 0.256 and 0.0890 respectively). The rate of revision for infection was also the same in both groups (p = 0.452).ConclusionCementless TKA demonstrated an equivalent rate of aseptic and septic failure when compared to cemented TKA in the short-term. Time to aseptic failure was also similar in both groups.     

Intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty

Cement articulating spacers have been used for the treatment of TKA infection. The disadvantages of commercially available pre-made mobile spacers include limitations in implant size and antibiotic dose, often allowing delivery of only a single antibiotic agent. Hand-made mobile spacers fail to provide a well-shaped and congruently articular surface and have difficulties in maintaining stability. We present a method of intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty. A custom mold was made intraoperatively with bone cement and the standard posterior stabilized TKA provisional components which were of the same size as the original prosthesis. Fabrication of the spacers did not increase the overall surgical time. From 2004 to 2007, 17 infected total knee arthroplasties were treated with two-stage reimplantation. The average length of follow-up was 31 months. One patient required an above-knee amputation for persistent infection. A knee arthrodesis was performed in one case. Ten patients received reimplantation with Nexgen LCCK knee implants. Articulating spacers were retained in situ in five patients. This articulating spacer can help improve knee mobility and function during the interval between stages.     

Is obesity associated with short-term revision after total knee arthroplasty? An analysis of 121,819 primary procedures from the Dutch Arthroplasty Register

BackgroundThe prevalence of obesity is increasing. The association with knee osteoarthritis is well documented, resulting in the population requesting total knee arthroplasty (TKA) for invalidating symptoms to be heavier in nature. The purpose of the current analysis was to assess the association between preoperative body mass index (BMI) and short-term revision rate after TKA. The secondary aim was to investigate the influence of implant fixation method on the association between BMI and survivorship.MethodsThis is a retrospective analysis of prospectively collected registry data (Dutch Arthroplasty Register; LROI). All primary TKA procedures in patients >18 years of age with registered BMI were selected (n = 121,819). Non-obese patients (BMI 18–25) were compared with overweight (BMI 25–30) and class I–III obese (BMI >30, >35, >40) patients. Crude all-cause revision rates were calculated using competing risk analysis. Adjusted hazard ratios (HRs) were determined with Cox multivariable regression analyses for all-cause, septic and aseptic revision and secondary patellar resurfacing.ResultsRevision rates were 3.3% for non-obese patients, 3.5% for overweight patients, 3.7% for class I obese patients, 3.6% for class II obese patients and 3.7% for class III obese patients. Class III obese patients had a significant higher risk for septic revision compared with non-obese patients (HR 1.53, 95% confidence interval (CI) 1.06–2.22). Class I obese patients had a higher risk for secondary patellar resurfacing (HR 1.52, 95% CI 1.12–2.08). All-cause and aseptic revision rates were similar between BMI groups.ConclusionsObesity appeared to be associated with some short-term revision risks after TKA, but was not associated with an overall increase in revision rate.     

Satisfactory results at 8 years mean follow-up after ADVANCE® medial-pivot total knee arthroplasty

BackgroundAlthough good overall results have been reported with TKA, certain problems and limitations remain, primarily due to postoperative differences in joint kinematics, when compared with the normal knee. ADVANCE® Medial-Pivot TKA involves replicating the medial pivoting behavior observed in normal knees. Here, we aimed to investigate the clinical and radiological results and complications of TKA using this implant, at mid-term follow-up.MethodsFrom January 2001 to March 2012, we retrospectively selected 76 patients (85 knees; mean age at operation, 70.2 ± 8.1 years; range, 51–88 years) with a mean follow-up period of 93.1 ± 14.3 months (range, 72–132 months). Indications for TKA included primary degenerative osteoarthritis (60 knees), rheumatoid arthritis (22 knees), osteonecrosis (two knees), and osteoarthritis following high tibial osteotomy (one knee). The clinical and radiographic results were evaluated.ResultsKaplan–Meier survivorship analysis indicated a success rate of 98.3% (95% confidence interval, 96.6–99.9%). Comparison of pre- and postoperative knee extension angles and ranges of motion showed significant improvement postoperatively, in both the Knee Society Scores (KSS) and Knee Society Functional Scores (KSFS) (p < 0.05). In one case, radiographic assessment indicated implant loosening due to infection; however, despite this complication, significant improvement of postoperative varus or valgus deformity angles were noted in all cases (p < 0.05).ConclusionPatients undergoing ADVANCE® Medial-Pivot TKA achieved excellent clinical and radiographic results without any implant-related failures at mid-term follow-up.Level of evidence: Level IV     

Functional characteristics of female patients based on ambulatory ability 1 year after total knee arthroplasty

BackgroundTotal knee arthroplasty (TKA) is commonly performed to reduce knee pain and improve physical function. Compared with the values for healthy, age-matched women, previous studies have reported large deficits in functional ability, such as muscle strength and ambulatory ability, in women 1 year post-TKA. Ambulatory ability is to move around, particularly by walking and is clinically assessed by the timed up and go test (TUG).AimThis study aimed to clarify the characteristics of knee functions in female patients whose ambulatory ability recovered to a normal level at 1 year after TKA.MethodsThis cross-sectional study included 151 female patients who underwent TKA. The muscle strength of the lower extremity was measured, and the 2011 Knee Society Scoring (2011 KSS) system was used postoperatively. The TUG was conducted to assess ambulatory ability after TKA; then the patients were classified into the fast and slow ambulation groups based on previously reported gait-speed values of healthy female individuals. Then, we identified significant indicators of ambulatory ability at 1 year after TKA.ResultsForty-nine percent of patients after TKA achieved the level of ambulatory ability of a healthy female. Logistic regression analysis identified that the non-operative side knee extensor strength and the functional activity score, as assessed by the 2011 KSS, were variables significantly associated with the mid-term ambulatory ability after TKA.ConclusionFemale patients with high non-operative knee extensor strength and a functional activity score at 1 year postoperatively can achieve better ambulatory ability than those of healthy, age-matched females.     

Knee arthroplasty utilization trends from 2010 to 2019

BackgroundInterest in partial knee arthroplasty procedures including unicompartmental arthroplasty (UKA), patellofemoral arthroplasty (PFA), and bicompartmental knee arthroplasty (BKA) has increased due to their bone and ligament preservation compared to total knee arthroplasty (TKA). Implant designs, changing thoughts on appropriate indications for partial knee arthroplasty, and availability of navigation also impacted the field over the last decade. The aims of this study were to evaluate trends over the last decade in utilization of 1) partial and total knee arthroplasty; and 2) computer-assistance in knee arthroplasty.MethodsA retrospective cohort analysis was conducted using the PearlDiver database. Patients who underwent PFA, UKA, BKA, and TKA for an indication of osteoarthritis (OA) were identified using Current Procedural Terminology (CPT) codes. Trends analysis from 2010 to 2019 was conducted to compare utilization based on procedure type and computer-assistance. Statistical analysis was conducted using Compounded Annual Growth Rates (CAGR) and linear regression.ResultsFrom 2010 to 2019, there was a significant decrease in utilization of PFA (CAGR: −5.73 %; p = 0.011) and BKA (CAGR: −10.49 %; p = 0.013), but no significant difference in that of UKA (p = 0.224) and TKA (p = 0.421). There was a significant increase in the utilization of computer assistance for both UKA (CAGR: +19.81 %; p = 0.002) and TKA (CAGR: +3.90 %; p = 0.038), but there was no significant difference for computer-assisted PFA (p = 0.724) and BKA (p = 0.951).ConclusionsTKA is still the most common arthroplasty procedure for OA. Decreased utilization of PFA and BKA may be explained by reported failure and revision rates for PFA and BKA compared to TKA.     

Preliminary investigation of rate of torque development deficits following total knee arthroplasty

BackgroundTo assess changes in maximal strength and rate of torque development (RTD) following TKA, and examine the relationships between these measures and physical function.MethodsThirty-five TKA patients and 23 controls completed isometric knee extensor torque testing preoperatively, 1, and 6 months after surgery. Maximal strength was calculated as the peak torque during a maximal voluntary isometric contraction (MVIC) of the knee extensor muscles, peak RTD (RTD_peak) was calculated as the maximum value from the 1st derivative of the isometric knee extension torque data, RTD_25% and RTD _50% were calculated as the change in force over the change in time from force onset to 25% and 50% MVIC. Physical function was measured using a timed-up-and-go (TUG) and stair climbing test (SCT).ResultsRTD was significantly lower in the TKA group, at all-time points, compared to the Controls. MVIC and RTD significantly decreased 1-month following surgery (p = 0.000 for all measures). RTD_peak measures added to linear regressions with strength improved the prediction of TUG scores (p = 0.006) and the SCT scores (p = 0.015) 1-month post-surgery. Adding RTD_50% to the regression model, following MVIC, improved predicting both TUG (p = 0.033) and SCT (p = 0.024). At 6-months, the addition of RTD_25% to the regression model, following MVIC, improved the prediction of TUG (p = 0.037) and SCT (p = 0.036).ConclusionFollowing TKA, physical function is influenced by both the maximal strength and the rate of torque development of the knee extensors, and the prediction of function is improved with the addition of RTD compared to that of maximal strength alone.     

Early postoperative predictors of satisfaction following total knee arthroplasty

BackgroundDespite the excellent total knee arthroplasty (TKA) results reported using traditional outcome measures, dissatisfaction rates of up to 30% are reported following surgery. Although several preoperative factors have been identified as possible predictors of satisfaction, there is conflicting evidence. Identification of dissatisfaction in the early postoperative assessment may therefore be an alternative consideration.MethodsWe examined the relationship between 12-month satisfaction, and early post-operative outcomes in a cohort of 486 TKA patients. Preoperative, and postoperative outcome measures at 3- and 12-months (Oxford knee score, pain score, SF12, and knee motion), were analysed and compared between patients who were satisfied and dissatisfied at 12-months following TKA. Mean scores, and postoperative change in scores were calculated. Postoperative outcomes were examined for correlation with satisfaction, and multivariate logistic regression models used to identify potential predictors of dissatisfaction.ResultsOverall satisfaction was 77.0%. No preoperative differences were observed between groups. Dissatisfaction was associated with worse postoperative status across all outcome measures (p < 0.001), except the 3-month SF12-physical component (p = 0.052). Dissatisfied patients demonstrated minimal further improvement or even worsening of outcome scores between 3- and 12-months postoperatively (p < 0.02). Both the 3-month OKS (OR = 1.15, p < 0.001), and knee flexion (OR = 1.03, p = 0.009) were significant predictors of subsequent 12-month satisfaction.ConclusionsDissatisfaction following TKA is associated with worse outcomes as early as 3 months following surgery, with minimal further improvement subsequently achieved at 12-months. Early postoperative assessment following TKA should therefore be considered, including clinical assessment, to identify those patients at risk of dissatisfaction.     

The oxford knee score minimal clinically important difference for revision total knee arthroplasty

BackgroundMinimal clinically important difference (MCID) is crucial for interpreting meaningful improvements in patient-reported outcome measures (PROMs). No previous study has evaluated the MCID for the Oxford Knee Score (OKS) in revision total knee arthroplasty (TKA). This study aimed to propose the OKS MCID for revision TKA.MethodsProspectively collected data from 191 patients who underwent revision TKA at a single institution was analysed. Clinical assessment was performed preoperatively and at 2 years using OKS and Short-Form 36 Physical Component Score (SF-36 PCS). MCID was evaluated with a three-pronged methodology, using (1) anchor-based method with linear regression, (2) anchor-based method with receiver operating characteristic (ROC) and area under curve (AUC), (3) distribution-based method with standard deviation (SD). The anchors used were improvement in SF-36 PCS ≥ 12, patient satisfaction, and implant survivorship following revision TKA.ResultsThe MCID determined by anchor-based linear regression method using improvements in SF-36 PCS was 4.9 points. The MCID determined by anchor-based ROC was 10.5 points for satisfaction (AUC = 74.8%) and 13.5 points for implant survivorship (AUC = 73.7%). The MCID determined by distribution-based method of 0.5 SD was 4.7.ConclusionThe proposed MCID for OKS following revision TKA is 4.9 points. Patients who achieve an improvement in OKS of at least 10.5–13.5 points by 2 years are likely to be satisfied with their surgery and not require a subsequent re-revision TKA. Patients undergoing revision TKA should aim for an improvement in OKS of at least 10.5–13.5 points as a target score.     

Femoral loosening of high-flexion total knee arthroplasty: The effect of posterior cruciate ligament retention and bone quality reduction

High-flexion total knee arthroplasty (TKA) may be more sensitive to femoral loosening than conventional TKA as the knee joint force increases during deep flexion. The objective of this study was to evaluate whether the probability of femoral loosening is equal in posterior cruciate ligament (PCL) retaining and substituting high-flexion knee implants and whether loosening is related to femoral bone quality. A three-dimensional finite element (FE) model of the knee was developed and a weight-bearing deep knee bend up to 155° was simulated. PCL conservation considerably increased the compressive tibio-femoral joint force as a maximal force of 4.7–6.0 × bodyweight (BW) was found, against a maximal force of 4.0 × BW for posterior-stabilized TKA. Roughly 14% of the fixation site beneath the anterior femoral flange was predicted to debond on the long-term in case of cruciate-retaining TKA compared to 20% in case of posterior-stabilized TKA. Reducing the femoral bone quality to 50% of its original bone mineral density increased the amount of potential anterior failure for cruciate-retaining TKA to 22% and posterior-stabilized TKA to 24%. We therefore conclude that the femoral fixation site has a similar failure potential for both cruciate-retaining and posterior-stabilized high-flexion TKA.     

Patients with Dupuytren’s Contracture,Ledderhose Disease,and Peyronie’s Disease are at higher risk of arthrofibrosis following total knee arthroplasty

BackgroundTotal knee arthroplasty (TKA) is a successful treatment for patients with late stage osteoarthritis, yet arthrofibrosis remains a consistent cause of TKA failure. Dupuytren’s, Ledderhose and Peyronie’s Diseases are related conditions of increased fibroblast proliferation. The aim of this study was to identify whether an association exists between these conditions and arthrofibrosis following TKA.MethodsPatient records were queried from 2010 to 2016 using an administrative claims database to compare the rates of arthrofibrosis, manipulation under anesthesia (MUA), lysis of adhesions (LOA), and revision TKA in patients with independent chart diagnoses of Dupuytren’s Contracture, Ledderhose, or Peyronie’s Diseases versus those without. Complications were queried and compared using multivariate logistic regression.ResultsPatients with Dupuytren’s (n = 5,232) and Ledderhose (n = 50,716) had a significantly higher rate of ankylosis following TKA: 30-days (OR, 1.54; OR, 1.23), 90-days (OR, 1.20; OR, 1.24), 6-months (OR, 1.23; OR, 1.23), and 1-year (OR, 1.28; OR, 1.23), while patients with Peyronie’s (n = 1,186) had a higher rate of diagnosis at 6-months (OR, 1.37) and 1-year (OR, 1.35). Patients with diagnoses of any of the fibroproliferative diseases had a statistically higher risk of MUA at 90-days, 6-month, and 1-year following primary TKA. These cohorts did not have a significantly higher rate of revision TKA.ConclusionThere is an increased odds risk of arthrofibrosis and MUA in patients who have undergone TKA and have a diagnosis of Dupuytren’s Contracture, Ledderhose, or Peyronie’s Diseases. Improvements to frequency and application of post-operative treatment should be considered in these cohorts to improve outcomes.     

Aseptic versus septic revision total knee arthroplasty: Patient satisfaction,outcome and quality of life improvement

We prospectively compared the clinical outcomes and patient satisfaction rates of aseptic (n = 30) versus septic revision TKA (n = 15) at a mean follow-up of 40 months. We hypothesized that the clinical results of septic revision TKA would be inferior to aseptic revision TKA. The indication for revision in aseptic group was stiffness in 11 patients, aseptic loosening in 13, patellar loosening or maltracking in 6 patients. Patients operated for infection had better post-operative Knee Society Scores (KSS), Function Scores and SF-36 Mental Scores than aseptic group but there were no significant differences in the satisfaction rates. Patients operated for infection had more improvement in their KSS (p = 0.004) and Function Scores (p = 0.02) than patients revised for stiffness. Moreover, patients operated on for patellar problems had higher satisfaction rates than patients revised for stiffness (p = 0.01) or aseptic loosening (p = 0.01). Thus, patients undergoing septic revision TKA had better outcomes compared to those with aseptic revision TKA. However, in the aseptic group, revision TKA for stiffness was associated with the poorest outcomes. The indication for aseptic revision is an important variable when discussing treatment and outcome with patients.     

Long-term outcome of knee arthroplasty in the setting of pigmented villonodular synovitis

Background

Pigmented villonodular synovitis (PVNS) is a rare, benign proliferation of the synovium, commonly affecting the knee. Arthroplasty can successfully manage arthrosis in this population; however, outcome data is limited. The purpose of this study was to investigate the oncologic and functional outcome of patients undergoing total knee arthroplasty (TKA) in the setting of PVNS.

Are soft tissue releases sufficient to correct moderate to severe flexion contractures during total knee replacement? Role of hamstring tenotomy and horizontal capsular release

BackgroundPerforming total knee arthroplasty (TKA) in arthritic knees with persistent flexion deformities is a challenging task because secondary tightening of surrounding soft tissues makes it difficult to achieve appropriate ligament balancing. In this study, we shared our algorithm for correction of flexion contractures of moderate to severe grade while performing TKA as well as their outcomes with 1 year of follow up.MethodsForty-three patients (61 knees) having knee arthritis with moderate to severe flexion contractures (Lombardi classification) were included in the study. We followed a stepwise algorithm of soft tissue releases for correction of flexion contracture, which included: removal of posterior osteophytes, release of posterior capsule, gastrocnemius release, horizontal capsular release, and hamstring tenotomy. Patients were followed up at 15 days, 6 weeks, 3 months and 1 year, and assessed clinically for residual flexion deformity (FFD), range of motion (ROM), New Knee Society (New KSS) score and Hospital for Special Surgery (HSS) score.ResultsPre-operative mean FFD 29.07 ± 18.04 standard deviation (SD) was corrected to 0.77 ± 2.93 SD at 1 year follow up. Pre-operative mean ROM 71.37 ± 22.18 increased to 107.7 ± 10.38 at 1 year follow up. There was statistically significant improvement in mean New KSS score and reduction in number of cases with poor HSS score at 1 year follow up.ConclusionsModerate flexion contractures can be corrected with soft tissue releases without distal femoral over-resection. In severe deformities, horizontal release of posterior capsule and hamstring tenotomy are crucial, and residual contractures of up to 20° can be well corrected by postoperative physiotherapy and extension bracing.     

Assessment of isometricity before and after total knee arthroplasty: A cadaver study

Total knee arthroplasty (TKA) relies on soft tissue to regulate joint stability after surgery. In practice, the exact balance of the gaps can be difficult to measure, and various methods including intra-operative spreaders or distraction devices have been proposed. While individual ligament strain patterns have been measured, no data exist on the isometricity of the soft tissue envelope as a whole. In this study, a novel device was developed and validated to compare isometricity in the entire soft tissue envelope for both the intact and TKA knee.A spring-loaded rod was inserted in six cadaver knee joints between the tibial shaft and the tibial plateau or tibial tray after removing a 7 mm slice of bone. The displacement of the rod during passive flexion represented variation in tissue tension around the joint. The rod position in the intact knee remained within 1 mm of its initial position between 15° and 135° of flexion, and within 2 mm (± 1.2 mm) throughout the entire range of motion (0–150°). After insertion of a mobile-bearing TKA, the rod was displaced a mean of 6 mm at 150° (p < 0.001). The results were validated using a force transducer implanted in the tibial baseplate of the TKA, which showed increased tibiofemoral force in the parts of the flexion range where the rod was most displaced. The force measurements were highly correlated with the displacement pattern of the spring-loaded rod (r = − 0.338; p = 0.006).A simple device has been validated to measure isometricity in the soft tissue envelope around the knee joint. Isometricity measurements may be used in the future to improve implantation techniques during TKA surgery.     

When does postoperative standing function after total knee arthroplasty improve beyond preoperative level of function?

The purpose of the current study was to investigate inpatient recovery process during relaxed standing, and to clarify the question of when postoperative standing function would improve beyond preoperative level of function following total knee arthroplasty (TKA).Thirty patients with bilateral knee osteoarthritis, averaged 75 years old, participated. Subjects underwent unilateral TKA. Evaluations were divided into two categories; subjective and objective components. Subjective component was based on pain level (Visual Analog Scale: 100 mm), and objective component consisted of vertical knee force (%BW) and knee flexion angle (degrees) during relaxed standing. Data evaluations were done pre- and post-operatively.Preoperative pain score was 69.1. After TKA, pain level became maximum (89.9) and significantly larger on postoperative day 3. Thereafter, pain gradually decreased, and it (60.4) was significantly smaller on postoperative day 8 than preoperative score. Preoperative vertical knee force was 43.5%BW. After TKA, it became minimum (32.8) on postoperative day 3. Thereafter, knee force gradually increased, and it (44.1) was significantly larger on postoperative day 17. Preoperative knee flexion angle was 15.6°. After TKA, knee flexion angle during standing became maximum (20.0) on postoperative day 4. Thereafter, subjects could gradually extend the knee, and on postoperative day 16, it (14.3°) was smaller.From our results, subjective pain was significantly reduced from postoperative day 8, and objective knee condition, including vertical knee force on TKA side and knee flexion angle on TKA side during standing, significantly became better from postoperative day 17 and 16, respectively.