LCS mobile bearing total knee arthroplasty without patellar resurfacing. Does the unresurfaced patella affect outcome? Survivorship at a minimum 10-year follow-up

BackgroundPatellar resurfacing during total knee arthroplasty (TKA) remains controversial. The aim of this study was to evaluate the long-term outcomes of a mobile-bearing TKA without patellar resurfacing.MethodsWe assessed the outcomes in 503 patients (600 knees) who had cemented LCS (low contact stress) mobile bearing TKA without patellar resurfacing at a minimum follow-up of 10 years. Clinical outcome scores and radiological assessment were used.ResultsFour knees were revised, two had bearing dislocation and nine patients (1.5%) had secondary resurfacing for anterior knee pain. There were no radiolucent lines or osteolytic defects on radiographic evaluation.The overall survivorship was 97.8% with re-operation for any reason as the endpoint.ConclusionNon-resurfacing of the patella does not adversely affect the outcome of the LCS mobile bearing TKA at minimum 10 years follow-up.     

Gender optimized patellar component designs are needed to better match female patellar anatomy

BackgroundAvoidance of both over-resection of the native patella, and over-stuffing of the patello-femoral joint are advocated to reduce the risk of patellar complications following patellar resurfacing. Female gender, due to thinner native patella, and use of patellar prostheses from one specific manufacturer that were thicker for comparable diameters than the patellar prostheses from a second manufacturer were hypothesized to be risk factors for these undesirable technical outcomes.MethodsA retrospective review was undertaken of 803 consecutive knee replacements, performed by one surgeon, during which the same patellar resurfacing technique had been used, but with two different patellar implant designs.ResultsFemale gender, and use of one specific design of patella prostheses were associated with both increased risk of patellar over resection to ≤ 13 mm residual patellar thickness, and creation of a patella construct that was thicker than the native patella (p < 0.001).ConclusionsPatellar prostheses design can contribute to compromises in surgical technique during patellar resurfacing in TKA in female patients with thinner patellae. Modifications to current patellar prosthesis dimensions may be considered to allow surgeons to more accurately resurface the thinner, native female patella.Level of EvidenceIII     

Evaluation of a minimally aggressive method of patellofemoral osteoarthritis treatment at 10 years minimum follow-up

BackgroundKnee osteoarthritis mainly affecting the lateral facet of the patella, especially in young patients, is a definite challenge to the surgeon. Our purpose was to investigate the long-term outcome of a simple operation such as the partial lateral facetectomy on middle-aged to elderly patients with predominant lateral patellofemoral osteoarthritis.MethodsA retrospective, long-term study of 39 knees (28 females, mean aged at surgery 61 years old) with a minimum follow-up of 10 years was performed. Evaluations included preoperative and postoperative questionnaires, physical examinations, and radiographs.ResultsThe main outcomes included the initial anterior pain relief, with higher scores using the Knee Society Score (that improved in 84% of the knees), and the eventual failure of the technique, including percentage of patients that required secondary total knee replacement (30% of the knees).ConclusionPartial lateral facetectomy aiming to decrease the high pressure in the lateral facet of the patella confirmed frequent pain relief. This surgical procedure being minimally invasive, relatively simple, and effective in selected patients, is a valid early alternative to more complex operations and does not preclude further reconstructive surgery in case of disease progression.     

Does malrotation of components correlate with patient dissatisfaction following secondary patellar resurfacing?

BackgroundThe aim of our study was to identify whether there was any correlation between the outcome of secondary patellar resurfacing and malrotation of either the femoral or tibial component.MethodsWe identified patients that underwent secondary patellar resurfacing following previous primary total knee arthroplasty (TKA) at a single, large orthopaedic department. Patients were reviewed for range of movement, satisfaction, health status and knee function. CT scanning was performed, assessing rotational alignment of the components.ResultsTwenty-one patients (23 knees) were reviewed. Nine out of 21 (39%) were satisfied while 14 (61%) remained dissatisfied after the secondary patellar resurfacing. There were no complications after the secondary procedure. All knees were internally rotated. The mean femoral internal rotation in the satisfied group was 0.92°, and in the dissatisfied group was 2.88° of internal rotation. In the dissatisfied group eight out of 14 TKAs were in > 3° femoral internal rotation compared with only one in nine TKAs in the satisfied group (p < 0.05).ConclusionsInvestigation for malrotation should be considered in patients with post-operative pain, especially anteriorly, causing significant dissatisfaction amongst patients following TKA. This is especially true if the patella has not been primarily resurfaced and secondary resurfacing is being considered. Patients with more than 3^° of femoral internal rotation undergoing secondary patella resurfacing should be warned of the possibility of a poor outcome. It may well be that if the underlying problem is component malrotation, revision knee replacement may lead to a more satisfactory outcome than secondary resurfacing alone.Level of EvidenceLevel of Evidence III.     

Secondary resurfacing of the patella in total knee arthroplasty

Anterior knee pain following primary total knee arthroplasty is common and can be difficult to treat satisfactorily. We reviewed 28 consecutive patients (29 knees) who underwent secondary resurfacing of the patella for persistent anterior knee pain and report on the results. Mean follow-up was 28 months (range 12–61) with no cases lost to follow-up. Oxford knee scores, range of motion, the patient's assessment of outcome and overall satisfaction were recorded.Seventeen out of 19 (59%) felt their knee was better following patellar resurfacing, 10 out of 29 (34%) felt it was the same and two out of 29 (7%) felt it was worse. There was a significant improvement in Oxford knee scores (p < 0.001) and significant increase in patient satisfaction (p < 0.001) following secondary resurfacing.While secondary resurfacing of the patella does not provide the solution for every case of anterior knee pain following total knee joint replacement, in greater than 50% of cases it can be effective at relieving symptoms and in this series carries a low risk of worsening symptoms or complications.     

Does patellar rim electrocautery have deleterious effects on patellar cartilage?

BackgroundCircumpatellar electrocauterization to destroy pain receptors during total knee arthroplasty without patellar resurfacing is commonly used to decrease postoperative knee pain. We aimed to evaluate the effect of denervation with electrocauterization on patellar cartilage.MethodsTwenty rabbits were randomly assigned to two equally sized case and control groups. The rabbits in the case group underwent surgery via the anterior midline skin incision and medial parapatellar arthrotomy, followed by denervation electrocauterization at a depth of 1 mm and a distance of 3 mm from the outer border of the patella. In the control group, surgery was identical to that performed in the case group, but without patellar denervation. Twelve weeks after surgery, all rabbits were sacrificed. Range of motion, macroscopic evaluation of cartilage using modified Outerbridge scoring, and histopathological assessment using a modified histologic scoring system for cartilage were evaluated.ResultsThree rabbits died during the study. Nine cases and eight animals from the control group were included in the final evaluation. All rabbits had passive full range of motion. Mean Outerbridge score was 2.0 in the case group and 0.37 in the control group (p = 0.002). There were statistically significant differences in cellularity (p = 0.016), loss of matrix (p = 0.004), and clustering of chondrocytes (p = 0.008) between the two groups. Microscopic variables as a whole were statistically significant (p = 0.001).ConclusionsCircumpatellar electrocauterization may result in cartilage destruction. So, we encourage caution in using routine electrocauterization in patients undergoing total knee arthroplasty.Level of evidencelevel II.     

Effect of medial–lateral malpositioning of the femoral component in total knee arthroplasty on anterior knee pain at greater than 8 years of follow-up

BackgroundThe trochlea is often medialized after total knee arthroplasty (TKA) resulting in abnormal patellar tracking, which may lead to anterior knee pain. However, due to the difference in shape of the natural trochlea and the patellar groove of the femoral component, a medialization of the femoral component of 5 mm results in an equal patellar position at 0–30° of flexion. We tested the hypothesis that more medialization of the trochlea results in a higher VAS pain score and lower Kujala anterior knee pain score at midterm follow-up.MethodsDuring surgery a special instrument was used to measure the mediolateral position of the natural trochlea and the prosthetic groove in 61 patients between 2004 and 2005. Patient reported outcome measures were used to investigate the clinical results (NRS-pain, NRS-satisfaction, KOOS-PS and Kujala knee score).ResultsIn total 40 patients were included. The mean follow-up was 8.8 years. A medialization of ≥ 5 mm resulted in a significantly lower NRS-pain (0.2 vs. 1.4; p = 0.004) and higher NRS-satisfaction (9.6 vs. 8.2; p = 0.045). Overall clinical results were good; KOOS-PS was 33.9 and Kujala knee score was 72.1.ConclusionsThe present study showed that a more medial position may result in a better postoperative outcome, which can probably be explained by the non-physiological lateral orientation of the trochlear groove in TKA designs.Level of evidence: Level III     

The effect of hip adduction angle on patellar position measured using real time ultrasound scanning

IntroductionThere are limited in vivo studies investigating the influence of the Iliotibial Band (ITB) on patellar position, despite numerous references in the literature to this relationship. The purpose of this study was to investigate how the ITB influences patellar position, in vivo, indirectly through alteration of frontal plane hip position.MethodTwelve healthy, asymptomatic, male subjects (age 23 ± 2.6 years) had their patellar position examined using real time ultrasound scanning. The knee was passively placed into 20° flexion and combined with hip neutral, 20° hip adduction and 20° hip abduction. Mean patellar position (distance from the lateral border of the patella to the edge of the intersection of the trochlear groove and lateral femoral condyle) was measured, with the smaller values representing a position whereby the patella is drawn more laterally and closer to the lateral femoral condyle.ResultsMean patellar position for neutral was 8.1 mm (± 1.72 mm). Following 20° hip abduction the mean patellar position was 8.9 mm (± 1.79 mm), this was a statistically significant change in patellar position (p = 0.003). Following 20° hip adduction the mean patellar displacement was 7.3 mm (± 1.4 mm) which, again, was a statistically significant change in patellar position (p = 0.009). The results indicate that with the hip adduction the patella was positioned significantly more laterally (smaller value for distance).DiscussionThe results of this study support the hypothesis that hip adduction which is likely to create loading and lengthening of the ITB causes significantly greater lateral displacement of the patella, than when the hip is abducted and the ITB unloaded.Level of evidence: 2b individual cohort study.     

The influence of asymmetric quadriceps loading on patellar tracking — An in vitro study

BackgroundIn patients with anterior knee pain and patellar instability, a specific training of the quadriceps muscle – especially the vastus medialis – is often recommended, although the practicability is discussed controversially and the proof of a measurable clinical effect is difficult. Therefore, this in vitro study investigates the influence of asymmetric muscle loading on the motion of the human patella.MethodsSeven human knee specimens were tested in a specially developed knee simulator. During simulated weight-bearing knee flexion, the kinematics of tibia, femur and patella were measured using an ultrasound motion capture system. The quadriceps forces were controlled to achieve a constant ankle force over the whole flexion range which is assumed to represent almost physiological loading. Three different force distributions of the quadriceps were tested — a central, equally distributed load as well as mainly lateral and medial loads.ResultsA significant influence of different quadriceps force distributions was found for patellar tilt around a proximodistal axis (up to 1.7°) and patellar rotation around an anteroposterior axis (up to 3.8°) with respect to the femur. Interestingly, the patellar mediolateral shift was influenced only marginally (< 1.5 mm).ConclusionsSpecific muscle training might help patients with patellofemoral pain and cartilage damage by a slight modification of the kinematics, but we could show that even highly asymmetric quadriceps loads only led to a small alteration of the mediolateral shift in case of a physiologic anatomy of the trochlear groove.     

Clinical and radiologic outcomes of total knee arthroplasty using the Advance Medial Pivot prosthesis. A mean 7 years follow-up

BackgroundMedial Pivot total knee prosthesis has been designed according to studies on normal knee kinematics aiming to replicate physiological knee movement. The purpose of this study was to evaluate clinical and radiologic results of the Advance Medial Pivot Total Knee Arthroplasty, at a mean follow-up of seven years.MethodsOne hundred seventy two Medial Pivot total knee arthroplasties in 160 consecutive patients have been evaluated using the American Knee Society Score and the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Statistical analysis was performed using the Student's t-test and the Wilcoxon matched-pairs signed-rank (Mann–Whitney) test in order to evaluate the significance of differences within the groups of patients. Patients compliance was 93.75% thus only six patients (3.75%) lost to follow-up and four patients (2.5%) died for reasons unrelated to the surgery.ResultsThe mean Knee Society score and range of motion was improved from 77.6 points and 97.7° to 152.8 points and 112.5° respectively (p < .001). In total 85.8% and 82.4% of the knees had an excellent (≥ 80) or good (70–79) functional and knee scores respectively. Relief of pain was satisfactory in 88.9% of the patients, while 96% of the patients return to age-related daily life activities. Stability and comfort during walking was subjectively judged by the patients as satisfactory in about 90%. Anterior knee pain was observed in eight patients (5.4%). The Kaplan–Meier survivorship analysis showed a cumulative success rate of 98.6%.ConclusionsThe results are encouraging but longer follow-up of this cohort is necessary in the study of this specific design.Level of evidence IV     

Inter-rater reliability of the GNRB® knee arthrometer

BackgroundIn clinical settings, where arthrometers are mainly used by different clinicians, knowing the inter-rater reliability of the instrument is crucial in order for the results from different examiners to be accurately interpreted and limitations fully understood. The aim of this study was to evaluate the inter-rater reliability of the GNRB® knee arthrometer.MethodsKnee anterior laxity in both knees was tested in a group of young, uninjured subjects (N = 27, 13 females) by two examiners. Knee anterior laxity was calculated at test forces of 134 N and 250 N with values presented for the unstandardised and standardised conditions (relative to patellar stabilisation force).ResultsThe ICCs ranged from 0.220 to 0.424.ConclusionsThe inter-rater reliability of the GNRB® knee arthrometer is low.     

Should the position of the patellar component replicate the vertical median ridge of the native patella?

Background

In total knee arthroplasty (TKA), the position of the patellar component can affect patellar tracking. However, the patellar component cannot always replicate the original high point of the patella because of anatomical variance. This study investigated whether altering the highest point of the patella can affect outcomes of primary TKA, especially in patients having a patella with a far-medialized median ridge.

Does preoperative anxiety and depression predict satisfaction after total knee replacement?

Background and purposeApproximately one fifth of patients are not satisfied with the outcome of total knee arthroplasty (TKA). Preoperative variables associated with poorer outcomes are severity and chronicity of pain, psychological disease, poor coping strategies and pain catastrophisation. Psychological disease may be expressed as anxiety and depression. It is unclear whether anxiety and depression before TKA are constitutional or result from knee pain. The aim of this study was to explore the association of anxiety and depression with knee pain and function using specific outcome measures.MethodsForty consecutive patients undergoing TKA completed Hospital Anxiety and Depression Scale (HAD) and Oxford Knee Scores (OKS) preoperatively and at 3 and 6 months postoperatively.ResultsThe HAD and OKS significantly improved post-operatively (p < 0.001). There was a greater change between the preoperative and postoperative scores in the OKS than the HAD. The severity of preoperative anxiety and depression was associated with higher levels of knee disability (coefficient ? 0.409, p = 0.009). Postoperatively reduction in anxiety and depression was associated with improvement in knee disability after 3 (coefficient ? 0.459, p = 0.003) and 6 months (coefficient ? 0.428, p = 0.006).InterpretationThe difficulty in interpreting preoperative anxiety and depression and the outcome of TKA is establishing whether they are the cause or effect of pain in the knee. As anxiety and depression improve with knee pain and function, this study suggests that knee pain contributes to the psychological symptoms and that a successful TKA offers an excellent chance of improving both.     

Influence of low back pain on total knee arthroplasty outcome

BackgroundPreoperative pain and functional status are strong determinants of postsurgical success in total knee arthroplasty. Patients suffering chronic pain from other coexistent musculoskeletal problems may respond differently postoperatively, with potentially poorer outcomes after surgery. The aim of the study was to determine the influence of low back pain on the outcome of total knee replacement surgery.MethodsAll patients completed Oxford Knee Scores (OKS), American Knee Society Scores (AKSS) and SF-12 (both physical and mental components). Patients were divided into those with (n = 40) and without a documented history of low back pain (n = 305).ResultsOKS, AKSS and SF-12 physical scores were significantly worse for patients with low back pain at 24 months following surgery. The mental component of the SF-12 measure demonstrated a significant improvement in median mental health post-operatively for patients with no current history of low back pain. In contrast the group with low back pain showed no improvement in mental health scores post-operatively.ConclusionThis study demonstrates that symptomatic low back pain influences functional outcome after total knee arthroplasty surgery and that patients with low back pain show limited or no improvement in mental health post-operatively.Level of evidence II.     

The association between radiographic severity and pre-operative function in patients undergoing primary knee replacement for osteoarthritis

ObjectiveTo determine the association between radiographic osteoarthritis (OA) and pre-operative function in patients undergoing primary knee replacement.MethodsSingle centre study examining pre-operative outcomes in a consecutive series of 525 patients who underwent primary knee replacement for OA between January 2006 and December 2007. Pre-operative data included: demographics, American Society of Anaesthesiologists (ASA) status and OA in the contralateral knee. The International Knee Society (IKS) rating and Short Form-12 (SF-12) were recorded for each patient. Pre-operative radiographs were read by a single observer for Kellgren and Lawrence (K&L) grading and Osteoarthritis Research Society International (OARSI) atlas features. Multiple linear regression was used to assess the strength of associations between radiographic OA severity and function, adjusting for clinically relevant variables.ResultsLateral tibiofemoral osteophyte grade was an independent predictor of pre-operative function as determined by the functional sub-scale of the IKS in patients undergoing primary knee replacement (coefficient = 2.58, p = 0.033). No associations were evident between pre-operative function and modified K&L, joint space narrowing, Ahlbäck attrition and coronal plane deformity. Other statistically significant predictors of poorer pre-operative function included: advancing age, female gender, knee pain and poorer SF-12 mental component summary scores which including osteophyte grade accounted for 24.6% of the variation in functional scores, (r = 0.496).ConclusionOsteophytes in the lateral compartment of the knee were associated with pre-operative function in patients with advanced knee OA. Further studies are required which examine individual radiographic features specifically in patients with advanced knee OA to determine their relationship to pre-operative pain and function.     

Wiberg Type III patellae and J-sign during extension compromise outcomes of total knee arthroplasty without patellar resurfacing

BackgroundUnderstanding the risk factors associated with postoperative pain and worse outcome can guide surgeons on whether primary patellar resurfacing is warranted during total knee arthroplasty (TKA). The purpose of this study was to determine whether clinical scores and pain after TKA without patellar resurfacing are correlated with patellar shape and postoperative patellar position and kinematics.MethodsRadiographs as well as anterior knee pain according to the Visual Analogue Scale (pVAS) were collected pre- and postoperatively for 100 knees aged 68 ± 7.7 years that received uncemented TKA without patellar resurfacing. At a minimum follow-up of 12 months the Forgotten Joint Score (FJS), the Oxford Knee Score (OKS) as well as the flexion range of motion and the presence of J-sign during active extension were recorded. Uni- and multivariable linear regression analyses were performed to determine associations between the collected clinical scores and patient demographic and radiographic data.ResultsPostoperative OKS (79 ± 14.4) was worse for Wiberg Type III patellae (β = − 11.4, P = .020, compared with Type II). Anterior pVAS (2 ± 2) was greater in knees with J-sign during extension (β = 2.8, P < .001). None of the other radiographic measurements (patellar tilt, congruence angle and lateral patellar displacement) were correlated with postoperative OKS or anterior pVAS.ConclusionIncongruent patellar shape (Wiberg Type III) is associated with worse clinical scores, and abnormal kinematics (J-sign) with increased pain after TKA without patellar resurfacing. The authors therefore recommend routine resurfacing for Wiberg Type III patellae, though further studies are required to confirm whether resurfacing truly improves clinical scores and pain in this subgroup.     

Minimum 6 year results of an uncemented trabecular metal tibial component in total knee arthroplasty

IntroductionThere are theoretical advantages of using a trabecular metal tibial component in total knee replacement (TKR) for long-term survival. We have previously reported outcomes at 3 years. We now report the clinical and radiological outcome of an unselected series of 109 knees at a minimum of 6 years follow up.MethodsPatient function was assessed in a research clinic using Oxford Knee Score (OKS), Clinical and Functional Knee Society Score (KSS) and SF-12 physical score. Up to date weight bearing radiographs were obtained.ResultsSeventy‐six knees in 72 patients were available for assessment. OKS scores were maintained from the 3‐year assessment with a mean of 36.1 (8.6). KSS and SF-12 scores declined slightly but only to a degree previously reported as normal age related change. The mean KSS at follow up was 87.2 (17.7). There was no radiographic evidence of loosening in any implant. There has been 1 revision for unexplained pain at 27 months.ConclusionThe uncemented TMT in an unselected group is performing as well as any TKR implant at this stage. Future follow up is required to ensure this is maintained. The theoretical advantages may make this the prosthesis of choice in younger patients.Level of evidence: IV. Case series     

Knee joint preservation with combined neutralising high tibial osteotomy (HTO) and Matrix-induced Autologous Chondrocyte Implantation (MACI) in younger patients with medial knee osteoarthritis: a case series with prospective clinical and MRI follow-up over 5 years

PurposeThere is no ideal treatment for younger patients with medial knee osteoarthritis (OA) and varus malalignment. We have investigated the first case series of combined neutralising high tibial osteotomy (HTO) and Matrix-induced Autologous Chondrocyte Implantation (MACI) with MRI. Treatment goals were clinical improvement and delay of arthroplasty.MethodsBetween 2002 and 2005 18 patients (Mean age 47 years) underwent surgery. Exclusion criteria were lateral compartment and advanced patellofemoral OA. The Knee Injury and Osteoarthritis Outcome Score (KOOS), six minute walk test (6MWT) and a validated MRI score were outcome measures.ResultsThere were significant improvements (p < 0.05) in all five KOOS domains. Four were significantly maintained to 5 years. The domain “symptoms” and results in the 6MWT dropped off at 5 years. MRI results were first significantly improved (24/12) but declined at 60 months. Good quality infill was found in 33% patients at the study endpoint (n = 5/15). Histological investigation of one knee demonstrated full-thickness hyaline-like cartilage (20/12). After 2 early failures and one graft detachment graft fixation was changed (Smart nails instead of sutures in 14 cases). Graft hypertrophy requiring a chondroplasty occurred once. There were no other major complications. Specific minor complications included patellar tendinitis (n = 8).ConclusionsThis combined procedure provides a safe treatment option for younger patients with medial knee OA and varus alignment with significant clinical improvement at 5 years. However, overall graft survival and cartilage infill were poor. Larger studies are needed to statistically verify predictors for longer term cartilage repair in these patients.     

Patellar cartilage loss does not affect early outcomes of total knee arthroplasty performed without patella resurfacing

BackgroundThe aim of this study was to compare the outcomes and cost economics of TKA without patella resurfacing in patients with and without patellar cartilage loss.MethodsProspective case control study of 209 consecutive patients undergoing TKA without patella resurfacing. Patella cartilage status was documented intra-operatively: 108 patients had patella cartilage loss (mean age 70 ± 9.7, mean BMI 31 ± 6.2, 72 (67%) female) and 101 control patients did not (age 68 ± 9.2, BMI 31 ± 5.6, 52 (51%) female). The primary outcome measure was Oxford Knee Score (OKS) improvement at one year. Secondary outcomes included OKS, EQ-5D, anterior knee pain (AKP), Kujala scores and reoperation at 2–4 years. The cost to prevent secondary patella resurfacing was calculated.ResultsThere were more women in the patella cartilage loss group (67% Vs 51%, p = 0.037), but no other preoperative characteristics differed. There was no difference in OKS improvement between those with and without patella cartilage loss at 1 year (mean difference −1.03, −3.68 to 1.62 95%CI, p = 0.446) or 2–4 years (mean difference 1.52, −1.43 to 4.45 95%CI, p = 0.310). At 2–4 years there was no difference in AKP (14/87 with vs 17/80 without, p = 0.430) nor Kujala score (mean difference 2.66, −3.82 to 9.13 95%CI, p = 0.418). Routine patella resurfacing would have cost £58,311 to prevent one secondary resurfacing.ConclusionThere was no difference in OKS, anterior knee pain, reoperation or Kujala scores up to 2–4 years between patients with and without patellar cartilage loss following TKA without patella resurfacing. Resurfacing for this indication would not have been a cost effective intervention.