Tibial tubercle transfer leads to clinically relevant improvement in patients with patellar maltracking without instability: a systematic review and meta-analysis.

PURPOSE: To assess the different surgical techniques and their outcomes following tibial tubercle transfer (TTT) in patients with patellar maltracking. METHODS: A systematic search of the literature was performed in PubMed, EMBASE and Cochrane Library. Studies reporting patient-reported outcome measures (PROMs) or clinical outcome following: TTT in patients with patellar maltracking were included. Collected PROMs were Lysholm, Kujala, IKDC score, and VAS pain. Clinical outcome included reported clinical success, patient satisfaction, complications and removal of hardware (ROH). Overall pre-, post-operative and change scores were estimated using random-effects meta-analysis models. Results were reported as overall mean and per transfer direction. RESULTS: A total of 26 studies and 761 patients (818 knees, mean age 35 years, mean follow-up 5.0 years) were included. In 73% of the studies, surgery was performed after failed conservative treatment. Transfer direction was anteromedial in 76% of all procedures. Overall Lysholm score improved from 61 to 91, Kujala from 52 to 85, IKDC from 53 to 81, and VAS from 6.2 to 2.5, respectively. Clinical success was reported in 79% of patients, and 80% of patients reported to have satisfactory results. Rates of complications and ROH were 13% and 29%, respectively. CONCLUSIONS: TTT for management of patellar maltracking can lead to good results with clinically meaningful improvement, an overall clinical success of 79% and overall patient satisfaction of 80% when appreciating the underlying anatomic condition and using appropriate technique. The level of evidence was low, and large-scale prospective, comparative cohort studies with uniform outcome scales are needed to confirm these findings. LEVEL OF EVIDENCE: IV.

Cost effectiveness of patellofemoral versus total knee arthroplasty in younger patients.

AIMS: Patellofemoral arthroplasty (PFA) has experienced significant improvements in implant survivorship with second generation designs. This has renewed interest in PFA as an alternative to total knee arthroplasty (TKA) for younger active patients with isolated patellofemoral osteoarthritis (PF OA). We analysed the cost-effectiveness of PFA versus TKA for the management of isolated PF OA in the United States-based population. PATIENTS AND METHODS: We used a Markov transition state model to compare cost-effectiveness between PFA and TKA. Simulated patients were aged 60 (base case) and 50 years. Lifetime costs (2015 United States dollars), quality-adjusted life year (QALY) gains and incremental cost-effectiveness ratio (ICER) were calculated from a healthcare payer perspective. Annual rates of revision were derived from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. Deterministic and probabilistic sensitivity analysis was performed for all parameters against a $50 000/QALY willingness to pay. RESULTS: PFA was more expensive ($49 811 versus $46 632) but more effective (14.3 QALYs versus 13.3 QALYs) over a lifetime horizon. The ICER associated with the additional effectiveness of PFA was $3097. The model was mainly sensitive to utility values, with PFA remaining cost-effective when its utility exceeded that of TKA by at least 1.0%. PFA provided incremental benefits at no increased cost when annual rates of revision decreased by 24.5%. CONCLUSIONS: Recent improvements in rates of implant of survival have made PFA an economically beneficial joint-preserving procedure in younger patients, delaying TKA until implant failure or tibiofemoral OA progression. The present study quantified the minimum required marginal benefit for PFA to be cost-effective compared with TKA and identified survivorship targets for PFA to become both less expensive and more effective. These benchmarks might be used to assess clinical outcomes of PFA from an economic standpoint within the United States healthcare system. Cite this article: Bone Joint J 2017;99-B:1028-36.

Impingement following anterior cruciate ligament reconstruction: comparing the direct versus indirect femoral tunnel position.

PURPOSE: During anterior cruciate ligament (ACL) reconstruction, authors have suggested inserting the femoral tunnel at the biomechanically relevant direct fibres, but this higher position can cause more impingement. Therefore, we aimed to assess ACL graft impingement at the femoral notch for ACL reconstruction at both the direct and indirect tunnel positions. METHODS: A virtual model was created for twelve cadaveric knees with computed tomography scanning in which a virtual graft was placed at direct and indirect tunnel positions of the anteromedial bundle (AM), posterolateral bundle (PL) or centre of the both bundles (C). In these six tunnel positions, the volume (mm3) and mid-point location of impingement (°) were measured at different flexion angles. RESULTS: Generally, more impingement was seen with the indirect position compared with the direct position although this was only significant at 90° of flexion for the AM position (97 ± 28 vs. 76 ± 20 mm3, respectively; p = 0.046). The direct tunnel position impinged higher at the notch, whereas the indirect position impinged more towards the lateral wall, but this was only significant at 90° of flexion for the AM (24 ± 5° vs. 34 ± 4°, respectively; p < 0.001) and C position (34 ± 5° vs. 42 ± 5°, respectively; p = 0.003). CONCLUSION: In this cadaveric study, the direct tunnel position did not cause more impingement than the indirect tunnel position. Based on these results, graft impingement is not a limitation to reconstruct the femoral tunnel at the insertion of the biomechanically more relevant direct fibres.

Survivorship and functional outcomes of patellofemoral arthroplasty: a systematic review.

PURPOSE: Historically poor results of survivorship and functional outcomes of patellofemoral arthroplasty (PFA) have been reported in the setting of isolated patellofemoral osteoarthritis. More recently, however, fairly good results of PFA were reported, but the current status of PFA outcomes is unknown. Therefore, a systematic review was performed to assess overall PFA survivorship and functional outcomes. METHODS: A search was performed using PubMed, Embase and Cochrane systems, and the registries were searched. Twenty-three cohort studies and one registry reported survivorship using Kaplan-Meier curve, while 51 cohort studies reported functional outcomes of PFA. RESULTS: Twelve studies were level II studies, while 45 studies were level III or IV studies. Heterogeneity was mainly seen in type of prosthesis and year the cohort started. Nine hundred revisions in 9619 PFAs were reported yielding 5-, 10-, 15- and 20-year PFA survivorships of 91.7, 83.3, 74.9 and 66.6 %, respectively, and an annual revision rate of 2.18. Functional outcomes were reported in 2587 PFAs with an overall score of 82.2 % of the maximum score. KSS and Knee Function Score were 87.5 and 81.6 %, respectively. CONCLUSION: This systematic review showed that fairly good results of PFA survivorship and functional outcomes were reported at short- and midterm follow-up in the setting of isolated patellofemoral osteoarthritis. Heterogeneity existed mainly in prosthesis design and year the cohort started. CLINICAL RELEVANCE: These results provide a clear overview of the current status of PFA in the setting of isolated patellofemoral osteoarthritis. LEVEL OF EVIDENCE: IV.

Early functional outcome after lateral UKA is sensitive to postoperative lower limb alignment.

PURPOSE: The predictive role of patient-specific characteristics and radiographic parameters on medial unicompartmental knee arthroplasty (UKA) outcomes is well known, but knowledge of these predictors is lacking in lateral UKA. Therefore, purpose of this study was to assess the predictive role of these parameters on short-term functional outcomes of lateral UKA. METHODS: In this retrospective cohort study, Western Ontario and McMaster Universities Arthritis Index scores were collected at 2-year follow-up (median 2.2 years, range 2.0-4.0 years) in 39 patients who underwent lateral UKA. Patient-specific characteristics included age, BMI and gender, while radiographic parameters included osteoarthritis severity of all three compartments and both preoperative and postoperative hip-knee-ankle alignment. RESULTS: BMI, gender, age and preoperative valgus alignment were not correlated with functional outcomes, while postoperative valgus alignment was correlated with functional outcomes (0.561; p = 0.001). Postoperative valgus of 3°-7° was correlated with better outcomes than more neutral (-2° to 3° valgus) alignment (96.7 vs. 85.6; p = 0.011). Postoperative alignment was a predictor when corrected for patient-specific characteristics (regression coefficient 4.1; p < 0.001) and radiological parameters (regression coefficient 3.8; p = 0.002). CONCLUSIONS: Postoperative valgus alignment of 3°-7° was correlated with the best short-term functional outcomes in lateral UKA surgery, while patient-specific parameters and preoperative alignment were not correlated with functional outcomes. Based on these findings, a surgeon should aim for valgus alignment of 3°-7° when performing lateral UKA surgery for optimal functional outcomes. LEVEL OF EVIDENCE: Prognostic study, Level II.

Why do patellofemoral arthroplasties fail today? A systematic review.

BACKGROUND: Historically poor results of patellofemoral arthroplasty (PFA) were reported in the setting of isolated patellofemoral osteoarthritis (OA). In order to lower PFA failure rates, it is important to identify failure modes using a standardized method. In this systematic review, PFA failure modes were assessed and compared in early vs. late failures and older vs. recent studies. METHODS: Databases of PubMed, Embase and Cochrane and annual registries were searched for studies reporting PFA failures. Failure modes in studies with mean follow-up <5years were classified as early failures while >5years were classified late failures. Cohorts started before 2000 were classified as older studies and started after 2000 as recent studies. RESULTS: Thirty-nine cohort studies (10 level II and 29 level III or IV studies) and three registries were included with overall low quality of studies (GRADE criteria). A total of 938 PFA failures were included and were caused by OA progression (38%), pain (16%), aseptic loosening (14%) and patellar maltracking (10%). Pain was responsible for most early failures (31%), while OA progression was most common in late failures (46%). In older studies, OA progression was more commonly reported as failure mode than in more recent studies (53% vs. 39%, p=0.005). CONCLUSION: This level IV systematic review with low quality of studies identified OA progression and pain as major failure modes. Reviewing these studies, appropriate patient selection could prevent PFA failures in select cases. Future studies assessing the role of PFA in isolated patellofemoral OA are necessary.

Patients with isolated lateral osteoarthritis: Unicompartmental or total knee arthroplasty?

BACKGROUND: Lateral unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are both reliable treatment options for patients with isolated lateral osteoarthritis (OA). However, studies comparing both procedures are scarce. Aims of this study were to (I) compare short-term functional outcomes following lateral UKA and TKA and (II) assess the role of patient characteristics on outcomes as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). METHODS: In this retrospective cohort study, 82 patients (48 undergoing lateral UKA and 34 undergoing TKA) were identified that presented with lateral OA and completed the WOMAC. Independent t-tests were used to compare outcomes following lateral UKA and TKA. RESULTS: Mean follow-up was 2.8 years (range: 2.0 - 5.0 years). Preoperatively, no differences between lateral UKA and TKA were seen (50.1±13.5 and 53.3±17.1, respectively, p=0.551). Postoperatively, lateral UKA patients reported better overall outcomes than TKA (90.5±11.7 vs. 81.8±17.9, p=0.017). Subgroup analysis showed better outcomes following lateral UKA than TKA in patients younger than 75 years (92.1±9.9 vs. 81.3±19.6, p=0.014) and in females (91.6±9.9 vs. 81.0±18.2, p=0.014). CONCLUSION: These findings indicate that lateral UKA has superior short-term functional outcomes compared to TKA in patients with isolated lateral OA. Better outcomes were especially seen in younger patients and females. These findings may help orthopedic surgeons choose treatment for patients presenting with lateral OA and optimize treatment for individual patients.

Systematic review of medial versus lateral survivorship in unicompartmental knee arthroplasty.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) has gained popularity in patients with isolated unicompartmental osteoarthritis. To our knowledge no systematic review has assessed and compared survivorship of medial and lateral UKA. We performed a systematic review assessing medial and lateral UKA survivorship and comparing survivorship in cohort studies and registry-based studies. METHODS: A search was performed using PubMed, Embase and Cochrane systems. Ninety-six eligible studies reported survivorship, of which fifty-eight reported medial and sixteen reported lateral UKA survivorship. Nineteen cohort studies and seven registry-based studies reported combined medial and lateral survivorship. RESULTS: The five-year, ten-year and fifteen-year medial UKA survivorship was 93.9%, 91.7% and 88.9%, respectively. Lateral UKA survivorship was 93.2%, 91.4% and 89.4% at five-year, ten-year and fifteen-year, respectively. No statistical difference between both compartments was found. At twenty years and twenty-five years survivorship of medial UKA was 84.7% and 80%, respectively, but no studies reported lateral UKA survivorship at these follow-up intervals. Survivorship of cohort studies was not significantly higher compared to registry-based studies at five years (94.3 vs. 91.7, respectively, p=0.133) but was significantly higher at ten years (90.5 vs. 84.1, p=0.015). CONCLUSION: This is the first systematic review that shows no difference in the five-, ten- and fifteen-year survivorship of medial and lateral UKA. We found a lower survivorship in the registry-based studies compared to cohort studies.

The head-shaft angle of the hip in early childhood: a comparison of reference values for children with cerebral palsy and normally developing hips.

The recognition of hips at risk of displacement in children with cerebral palsy (CP) is a difficult problem for the orthopaedic surgeon. The Gross Motor Function Classification System (GMFCS) and head-shaft angle (HSA) are prognostic factors for hip displacement. However, reference values for HSA are lacking. This study describes and compares the development of HSA in normal hips and children with CP. We selected 33 children from a retrospective cohort with unilateral developmental dysplasia of the hip (DDH) (five boys, 28 girls) and 50 children (35 boys, 15 girls) with CP with GMFCS levels II to V. HSA of normal developing hips was measured at the contralateral hip of unilateral DDH children (33 hips) and HSA of CP children was measured in both hips (100 hips). Measurements were taken from the radiographs of the children at age two, four and seven years. The normal hip HSA decreased by 2° per year (p < 0.001). In children with CP with GMFCS levels II and III HSA decreased by 0.6° (p = 0.046) and 0.9° (p = 0.049) per year, respectively. The HSA did not alter significantly in GMFCS levels IV and V. Between the ages of two and eight years, the HSA decreases in normal hips and CP children with GMFCS level, II to III but does not change in GMFCS levels IV to V. As HSA has a prognostic value for hip displacement, these reference values may help the orthopaedic surgeon to predict future hip displacement in children with CP.

The prognostic value of the head-shaft angle on hip displacement in children with cerebral palsy.

BACKGROUND: Hip displacement is the second most common deformity in cerebral palsy (CP). The risk for hip displacement is related to the Gross Motor Function Classification System (GMFCS). Recently, the head-shaft angle (HSA) has been identified as a predictor for hip displacement and the aim of this study is to assess the predictive value of the HSA for hip displacement in CP. METHODS: In this retrospective cohort, we performed radiological measurements in 50 children on both hips. In children with GMFCS level II (30 hips), III (30 hips), IV (20 hips) and V (20 hips), we measured the HSA and migration percentage (MP) in three age intervals: age two years (T1), age four years (T2) and age seven years (T3). RESULTS: At T1, the HSA was larger (more valgus) in hips that will displace than in hips that will not displace (174° vs. 166°; p = 0.001) and was also larger in higher GMFCS levels (IV-V vs. II-III) (172° vs. 165°; p < 0.001). At T1, GMFCS [odds ratio (OR) 14.7; p = 0.001] and HSA (OR 1.102; p = 0.043) were predictors for hip displacement at T3, but at T2, MP (OR 1.071; p = 0.010) was the only predictor for hip displacement at T3. CONCLUSIONS: The HSA at two years is larger in hips that will displace and larger in children with higher GMFCS levels (IV-V). At age two years, GMFCS and HSA are valuable predictors for hip displacement, but at the age of four years, only MP should be used in the prediction of hip displacement. LEVEL OF EVIDENCE: Prognostic study, level II.