Combined medial and lateral patellar retinaculum plasty for skeletally immature patients with patellar dislocation and low-grade trochlear dysplasia

BackgroundTo evaluate the clinical outcomes of combined medial and lateral patellar retinaculum plasty for skeletally immature patients with patellar dislocation and low-grade trochlear dysplasia.MethodsFrom December 2014 to December 2016, we reviewed 19 skeletally immature patients who underwent medial and lateral patellar retinaculum plasty at our institution. Clinical evaluations were performed pre- and postoperatively, and included determination of the number of patellar re-dislocation patients, the Kujala and Tegner scores, the patellar tilt angle, lateral patellar shift, and congruence angle. The radiographic evaluation parameters were measured on computed tomography scans.ResultsNo dislocation or subluxation occurred during the mean follow-up of 35.42 months (24–48 months). Postoperatively, the Kujala score improved from 57.6 ± 4.2 to 86.9 ± 8.1 (P < 0.05), and the Tegner activity score improved from 2.6 ± 1.0 to 5.0 ± 1.3 (P < 0.05). Radiographically, the patellar tilt angle decreased from 32.7 ± 5.9° to 13.4 ± 4.28° (P < 0.05), the lateral patellar shift decreased from 15.9 ± 1.1 mm to 8.4 ± 0.6 mm (P < 0.05), and the congruence angle decreased from 29.9 ± 15.3° to − 9.6 ± 15.5° (P < 0.05).ConclusionsMedial and lateral patellar retinaculum plasty is a promising procedure that has the advantage of being a simple operation that induces little trauma. It is a good treatment option for skeletally immature patients with patellar dislocation who have low-grade trochlear dysplasia.     

内侧髌股韧带重建治疗复发性髌骨脱位疗效观察

目的 探讨内侧髌股韧带重建治疗复发性髌骨脱位的临床效果.方法 回顾性分析湖北省荆州市中心医院2017年1月至2019年6月通过关节镜辅助下内侧髌股韧带双束重建治疗的29例复发性髌骨脱位患者的临床资料.其中,男10例,女19例,年龄14.0～29.5岁,平均19.4岁.测量TT-TG距离、髌骨倾斜角,计算Caton指数....     

Predictors of patellar alignment during weight bearing: An examination of patellar height and trochlear geometry

BackgroundPatellar malalignment is thought to be an etiological factor with respect to the development of patellofemoral pain. Although previous studies have suggested that the geometry of the femoral trochlea and the height of the patella play an important role in determining patellar alignment, no investigation has systematically examined these relationships during weight bearing. The aim of this study was to determine whether patellar height and/or trochlear geometry predicts patellar alignment (lateral patellar displacement and lateral patellar tilt) during weight bearing.MethodsMR images of the patellofemoral joint were acquired from 36 participants during weight bearing (25% of body weight) at 4 knee flexion angles (0°, 20°, 40° and 60°). Using the axial images, patellar alignment (lateral displacement and tilt) and femoral trochlear geometry (sulcus angle and inclination of the lateral femoral trochlea) were measured. Patellar height (Insall–Salvati ratio) was measured on reconstructed sagittal plane images.ResultsStepwise regression analysis revealed that at 0° of knee flexion, the height of the patella was the best predictor of lateral patellar tilt while the lateral trochlea inclination angle was the best predictor of lateral patellar displacement. Lateral trochlear inclination was the best predictor of patellar lateral displacement and tilt at 20°, 40° and 60° of knee flexion.ConclusionSimilar to a previous study performed under non-weight bearing condition, our findings suggest that lateral trochlear inclination is an important determinant of patellar alignment in weight bearing.Level of EvidenceLevel III     

Lateral retinacular release in concordance with medial patellofemoral ligament reconstruction in patients with recurrent patellar instability: A computational model

BackgroundThe aim of this study was to develop and validate a finite element (FE) model of the patellofemoral joint to analyze the biomechanics of lateral retinacular release after medial patellofemoral ligament (MPFL) reconstruction in patellar malalignment (increased tibial tubercle–trochlear groove distance (TT-TG)). We hypothesized that lateral retinacular release is not appropriate in patellar instability addressed by MPFL reconstruction due to decreased lateral stability and inappropriate adjustment in patellofemoral contact pressures.MethodsA FE in-silico model of the patellofemoral joint was developed and validated. The model was used analyze the effect of lateral retinacular release in association with MPFL reconstruction on patellofemoral contact pressures, contact area, and lateral patellar displacement during knee flexion.ResultsMPFL reconstruction alone results in restoration of patellofemoral contact pressures throughout the entire range of motion (0–90°), mimicking the results from healthy condition. The addition of the lateral retinacular release to the MPFL reconstruction resulted in significant reductions in both patellofemoral contact pressure and contact area. Lateral retinacular release resulted in more lateral patellar displacement during the mid-flexion knee range of motion.ConclusionsCombination of lateral retinacular release with MPFL reconstruction in patients with increased TT-TG is not recommended as MPFL reconstruction alone for first-line management of recurrent patellar instability offers a greater biomechanical advantage and restoration of contact forces to resemble that of the healthy knee. The presented biomechanical data outlines the effect of concomitant MPFL reconstruction and lateral retinacular release to help guide surgical planning for patients with recurrent patellar instability due to malalignment.     

Lateral patellar tilt and its longitudinal association with patellofemoral osteoarthritis-related structural damage: Analysis of the osteoarthritis initiative data

BackgroundIncrease in lateral patellar tilt-(LPT) can cause increased pressure on the lateral facet of the knee and can lead to patellar or femoral cartilage damage and further osseous changes. This study aims to test the hypothesis whether there is an association between increased LPT and MRI-based patellofemoral osteoarthritis-(OA) features at baseline and their worsening over a 2-year follow-up in participants of the Osteoarthritis Initiative-(OAI).MethodsRecorded clinical and imaging data of 600 participants in the FNIH-OA biomarkers consortium was extracted from its database. The LPT-(as the angle between the longest patella diameter and posterior aspect of condyles) was measured using the axial knee MRI. Associations of LPT (every 5° increase) with MRI OA Knee Scoring-(MOAKS) for OA-related features, including cartilage and bone marrow lesions (BMLs) in addition to knee cartilage volume at baseline and their worsening after 2-year follow-up were assessed using regression models adjusted for several possible confounders.ResultsThe mean LPT angle in this sample was 8.84° ± 5.19. In baseline, higher LPT was associated with lower cartilage volumes and higher cartilage lesions and BMLs MOAKS scores in the lateral trochlear and patellar subregions. Over the follow-ups, subjects with higher LPT measures in the baseline showed higher odds of experiencing BML score worsening in the lateral trochlear subregion-(OR:1.25[1.01–1.56]) over the 2-year follow-ups.ConclusionsIncrease in LPT measures may be associated with OA-related features in the trochlear subregion. Therefore, aside from its use as an indicator of patellofemoral instability syndrome, LPT may be associated with longitudinal progression of patellofemoral OA.     

Patellar resurfacing has minimal impact on in vitro tibiofemoral kinematics during deep knee flexion in total knee arthroplasty

BackgroundWhile patellar resurfacing can affect patellofemoral kinematics, the effect on tibiofemoral kinematics is unknown. We hypothesized that patellar resurfacing would affect tibiofemoral kinematics during deep knee flexion due to biomechanical alteration of the extensor mechanism.MethodsWe performed cruciate-retaining TKA in fresh-frozen human cadaveric knees (N = 5) and recorded fluoroscopic kinematics during deep knee flexion before and after the patellar resurfacing. To simulate deep knee flexion, cadaver knees were tested on a dynamic, quadriceps-driven, closed-kinetic chain simulator based on the Oxford knee rig design under loads equivalent to stair climbing. To measure knee kinematics, a 2-dimensional to 3-dimensional fluoroscopic registration technique was used. Component rotation, varus-valgus angle, and anteroposterior translation of medial and lateral contact points of the femoral component relative to the tibial component were calculated over the range of flexion.ResultsThere were no significant differences in femoral component external rotation (before patellar resurfacing: 6.6 ± 2.3°, after patellar resurfacing: 7.2 ± 1.8°, p = 0.36), and less than 1° difference in femorotibial varus-valgus angle between patellar resurfacing and non-resurfacing (p = 0.01). For both conditions, the medial and lateral femorotibial contact points moved posteriorly from 0° to 30° of flexion, but not beyond 30° of flexion. At 10° of flexion, after patellar resurfacing, the medial contact point was more anteriorly located than before patellar resurfacing.ConclusionDespite the potential for alteration of the knee extensor biomechanics, patellar resurfacing had minimal effect on tibiofemoral kinematics. Patellar resurfacing, if performed adequately, is unlikely to affect postoperative knee function.     

Patellar mobility and lower limb kinematics during functional activities in individuals with and without patellar tendinopathy

Study designCase-control.ObjectiveTo examine whether patients with patellar tendinopathy (PT) display greater patellar mobility and different lower body kinematics than patients without PT.BackgroundPT is a common overuse condition of the patellar tendon that can cause pain and impair function. Subjects with overuse knee problems display different hip and knee functional mechanics, specifically valgus collapse. Patellar hypermobility has not been specifically studied as a possible risk factor for PT.Methods11 patients with PT and 11 controls without PT, age 18 to 40, were studied. Using a patellofemoral arthrometer (PFA), maximal lateral and medial patellar displacement was measured. 3-D motion analysis was performed to determine lower extremity joint motions during single-leg step down and drop vertical jump tests.ResultsPatients with PT had significantly increased lateral patellar mobility compared to controls (12.21 ± 3.33 mm vs. 9.19 ± 1.92 mm, P = .017). PT patients showed significantly greater peak hip adduction with both drop vertical jump (2.7° ± 6.3° vs. -5.6° ± 4.2°; P = .003) and step down (17.0° ± 3.8° vs. 12.5° ± 4.4°, P = .024). PT patients demonstrated increased peak ankle external rotation with drop vertical jump (−21.1° ± 5.9° vs. −14.8° ± 5.5°, P = .023) and step down (−15.6° ± 5.5° vs. −9.0° ± 6.0°, P = .017).ConclusionsPatients with PT exhibit increased lateral patellar mobility, hip adduction, and ankle external rotation. The effects of increased patellar mobility deserve further study in the development, management, and prevention of PT.     

Combined deepening trochleoplasty and supracondylar external rotation osteotomy for recurrent patellar instability in patients with trochlear dysplasia and increased femoral antetorsion

BackgroundDeepening trochleoplasty has become a part of surgical management in patients with patellar instability and severe trochlear dysplasia. In addition, increased femoral antetorsion is treated most commonly by proximal femoral external rotation osteotomy.HypothesisDeepening trochleoplasty and supracondylar femoral external rotation osteotomy in combination improve patellar stability and function in patients presenting with recurrent patellar instability due to trochlear dysplasia and increased femoral antetorsion.Study designTherapeutic case series; Level IV.MethodsCombined deepening trochleoplasty and supracondylar external rotation osteotomy were performed in seven female patients (nine knees) with recurrent patellar instability. Trochlear dysplasia (Dejour classification) and increased femoral antetorsion (Murphy computed tomography (CT)-based measurement) were documented using magnetic resonance imaging and CT scans. Data were collected prospectively preoperatively, at 12 months, and at final follow-up. Complete data were available in 100% of cases. Clinical and functional outcomes were evaluated using the Kujala score and Tegner activity level scale.ResultsThe average age at the time of surgery was 22.2 years (range, 17–29 years). Preoperative MRI-based findings demonstrated in all patients significant trochlear dysplasia (B in two, C in five, and D in two knees). Femoral antetorsion was 37.8° on average (range, 27–51°). The mean follow-up was 2.1 years after surgery (range, 1–5.5 years). The median Kujala score was 41.2 preoperatively, rising to 83.1 at final follow-up (P = .015). The Tegner activity score improved from a mean preoperative score of 2.7 to a mean postoperative score of 6.0 (P = .020). Good patellar stability without positive apprehension sign was found in all patients. Poor outcome was associated with significant patellofemoral cartilage damage (grade IV) at the time of surgery. A total of 88.8% of patients were satisfied with the knee function at final follow-up. There were no postoperative complications.ConclusionThe combination of deepening trochleoplasty and supracondylar external rotation osteotomy performed in one step is an individually adapted surgical procedure for restoring both horizontal limb alignment and trochlear geometry. It improves patellar stability and yields good subjective and objective functional results in most cases. The condition of the cartilage at the time of surgery is crucial for the outcome with respect to the pain.     

Medial patellofemoral ligament reconstruction with autologous gracilis tendon: Clinical and radiological outcomes at a mean 6 years of follow up

BackgroundThe medial patellofemoral ligament (MPFL) is considered the primary soft tissue restrain to lateral translation of the patella during the first 15–30 degrees of knee flexion. The primary restraint thereafter is the slope of the lateral wall of the trochlea. A plenty of procedures are described in literature for MPFL reconstruction with different types of graft, angle of knee flexion for fixation and rehabilitation protocols. In this study we used MPFL reconstruction with doubled autologous gracilis tendon with the Schottle’s technique. The aim of our study is to evaluate outcomes at medium-long term follow up of MPFL reconstruction.MethodsPatients who underwent arthroscopic MPFL reconstruction for recurrent patellar dislocation were followed up for a minimum of 2 to 10 years. Patient-reported outcomes including the Kujala, Visual Analogue Scale (VAS) score were collected preoperatively and postoperatively. Clinical complications such as loss of ROM, recurrent sub-luxation or dislocation were recorded.ResultsA total of 38 patients with recurrent patellar dislocation were treated with MPFL reconstruction and data were available for final follow up (mean 72.3 months, SD 33.6). Mean age at time of surgery was 23.4 (SD 7.8). Mean number of dislocations before surgery was 7.1 (SD 10.5). Recurrent dislocations were not observed in any of the patients treated at last follow-up. Significant clinical improvements were also noted with Kujala and VAS score. Patellar tilt angle decreased significantly from pre to post-operative.ConclusionOur study demonstrated that MPFL reconstruction with patellar suture anchors fixation using autologous gracilis tendon is an effective, safe and reliable method for treating recurrent patellar dislocation.     

Lateral and patellofemoral compartment osteoarthritis progression after medial unicompartmental knee arthroplasty: A five- to 10-year follow-up study

BackgroundThe purpose of the study was to evaluate lateral and patellofemoral osteoarthritis (OA) progression after medial unicompartmental knee arthroplasty (UKA) and identify factors affecting the progression that were not identified previously.MethodsWe evaluated 146 patients who underwent medial UKA between 2009 and 2014. Kellgren–Lawrence grading of lateral and patellofemoral OA was performed on preoperative and final follow-up knee radiographs. Radiographic and clinical characteristics, SF-36, and Oxford knee scores were compared between the OA progressed and non-progressed groups. Risk factors for lateral and patellofemoral OA progression were evaluated.ResultsThe lateral OA progressed and non-progressed groups significantly differed in side, preoperative flexion contracture, preoperative joint line convergence angle, postoperative tibiofemoral angle, insert size, revision status (P < 0.05), and the patellofemoral OA progressed and non-progressed groups significantly differed in age, pre- and postoperative flexion contracture, postoperative tibiofemoral angle and pre- and postoperative patellofemoral OA grade (P < 0.05). At the final follow-up, Visual Analogue Scale, Oxford Knee Scores, and SF-36 sub-scores were significantly better in the lateral OA non-progressed group (P < 0.001).Dominant leg (odds ratio (OR): 2.759), insert size (> 4, OR: 2.219), revision status (+, OR: 6.692), and postoperative tibiofemoral angle (> 5.5°, OR: 1.177) were independent risk factors for lateral OA progression, whereas age (> 60 years, OR: 3.222), preoperative patellofemoral OA grade (> 1, OR: 2.085), and postoperative flexion contracture (> 10°, OR: 1.919) were those for patellofemoral OA progression.ConclusionsMild radiographic progression of 1 KL grade is frequently seen five to 10 years after medial UKA. Postoperative outcomes are significantly affected by lateral compartment OA progression but not by patellofemoral OA progression.     

High tibial derotation osteotomy for distal extensor mechanism alignment in patients with squinting patella due to increased external tibial torsion

BackgroundThe patellofemoral joint is often affected by torsional disorders of the lower limb, causing pain, instability and knee degeneration. The aims of this study were to determine functional outcomes of patients who underwent a high tibial derotation osteotomy (HTDO) for symptomatic squinting patella due to increased external tibial torsion. Moreover, factors associated with inferior clinical outcomes were investigated.MethodsPatients with symptomatic squinting patella, increased external tibial torsion (>30°) treated with this technique, and with 2 years of follow up were included. Fulkerson and Kujala patellofemoral joint scores were assessed. Age, body mass index, history of prior surgery, increased femoral anteversion, association of lateral retinaculum release and patellar cartilage lesions were analysed.ResultsSixty HTDOs were included in this retrospective study with an average of 66 months of follow up. The mean Kujala score improved from 47.5 preoperatively to 93 postoperatively. The mean Fulkerson score improved from 40.6 to 91.6. Kujala subscores for pain improved from 8.6 to 30.4, for instability improved from 6.4 to 17.9, and their ability to climb stairs increased from 6.9 to 17.9 (all P < 0.0001). Multivariate logistic regression model identified that patient age (P < 0.005) and advanced chondral damage (P < 0.001) were the dominant factors predicting inferior clinical outcomes using Kujala’s score.ConclusionHTDO provided good results regarding the pain symptoms, instability and the ability to climb stairs. Advanced chondral damage and advanced age had negative effects on outcomes.     

A comparison of tibiofemoral and patellofemoral alignment during a neutral and valgus single leg squat: an MRI study

BackgroundThe etiology of anterior knee pain is not well understood. Recently, excessive hip adduction and internal rotation have been cited as possible factors. However, how these altered hip mechanics affect the patellofemoral joint is still unclear.ObjectiveTo compare the three-dimensional tibiofemoral and patellofemoral alignment between a neutral squat and one performed with increased hip adduction and internal rotation. We aimed to examine the relationships between the three-dimensional tibiofemoral and patellofemoral alignment during a neutral and valgus squat. Finally, we aimed to determine the relationship between two-dimensional and three-dimensional measures of patellofemoral alignment.Methods10 healthy subjects were recruited for this study. Knee and patellar kinematics in a neutral squat and one performed with hip adduction and internal rotation were measured using a open, upright, magnetic resonance imaging unit. Both single leg squats were performed at 30° of knee flexion.ResultsThere was a significant correlation between knee external rotation and lateral patellar translation, and between knee abduction and lateral patellar translation. Moderate relationships were found between the 2D and 3D measures but these were not statistically significant.ConclusionThe valgus squat resulted in greater knee external rotation in all subjects. Although mean patellar mechanics were not different in the valgus squat, lateral patellar translation increased as knee external rotation increased. Lastly, 2D measures of patellofemoral alignment only provide moderately fair surrogates for 3D measures.     

Modern femoral component design in total knee arthroplasty shows a lower patellar contact force during knee flexion compared with its predecessor

BackgroundThe relationship between the femoral component design in total knee arthroplasty (TKA) and the patellofemoral contact force, as well as the soft tissue balance, has not been well reported thus far.MethodsTwenty-eight mobile-bearing posterior-stabilized (PS) TKAs using the traditional model (PFC Sigma) and 27 mobile-bearing PS TKAs using the latest model (Attune) were included. Surgeries were performed using the measured resection technique assisted with the computed tomography (CT)-based free-hand navigation system. After all the trial components were placed, patellar contact forces on the medial and lateral sides were measured using two uniaxial ultrathin force transducers with the knee at 0°, 10°, 30°, 60°, 90°, 120°, and 135° of flexion. The joint component gap and the varus ligament balance of the femorotibial joint were also measured. The non-paired Student’s t-test was conducted to compare the values of the two groups.ResultsThe medial patellar contact force was significantly lower for Attune group than for PFC Sigma group at 120° of knee flexion (P = 0.0058). The lateral patellar contact force was also significantly lower for Attune group than PFC Sigma group at 120° and 135° of knee flexion (P = 0.0068 and P = 0.036). The joint component gap, as well as the varus ligament balance, showed no statistically significant difference between the two groups.ConclusionsReduced thickness and width of the anterior flange of the femoral component in the Attune may play a role in low patellar contact force.     

关节镜辅助下三联法治疗儿童髌骨固定型脱位的疗效观察

目的　探讨关节镜辅助下应用异体韧带悬吊式重建内侧髌股韧带（MPFL）、外侧支持带Y形松解,结合股内侧肌成形治疗儿童髌骨固定型脱位临床疗效。 方法　回顾分析2014年1月至2017年1月收治10例12膝儿童髌骨固定型脱患者资料,男6例8膝,女4例4膝;年龄为4~9岁,平均6.6岁。所有患者均采用关节镜辅助下应用异体韧带悬吊式重建内侧髌股韧带（MPFL）、外侧支持带Y形松解,结合股内侧肌成形治疗儿童髌骨固定型脱位,术后随访根据髌骨稳定度及Kujala 评分评定膝关节功能恢复情况。 结果　10例儿童术后获得6~18个月（平均随访12个月）随访。所有儿童末次随访髌骨稳定度满意,Kujala 评分由术前的（42.12±14.37）分增加到随访时的（95.68±9.42）分,差异有统计学意义（P＜0.05）。 结论　关节镜辅助下应用异体韧带悬吊式重建内侧髌股韧带（MPFL）、外侧支持带Y形松解,结合股内侧肌成形治疗儿童髌骨固定性脱位临床疗效满意,可以有效增加髌骨稳定性,改善膝关节功能,对骨骺不造成损害,是一种有效的治疗儿童髌骨固定型脱位的手术方法。     

Clinical outcomes of medial patellofemoral ligament reconstruction using FiberTape and knotless SwiveLock anchors

BackgroundWe aimed to prospectively investigate the clinical outcomes of medial patellofemoral ligament (MPFL) reconstruction using polyester high-strength suture tape with knotless anchors.MethodForty-three patients (65 knees) were followed for at least 1 year postoperatively, with 27 patients (43 knees) followed for 2 years postoperatively. All patients underwent MPFL reconstruction using polyester high-strength suture tape (FiberTape®; Arthrex) with knotless anchors (SwiveLock®; Arthrex). Repeated dislocation and residual patellar apprehension signs were recorded, and congruence and tilting angles were measured. Changes in Knee Injury and Osteoarthritis Outcome Scale (KOOS) scores and their associations with the preoperative tibial tubercle–trochlear groove (TT-TG) distance were analyzed.ResultsNo repeat dislocations (0%) were observed. One (2.4%) residual positive patellar apprehension sign was noted. The mean tilting angle decreased from 24.8° to 10.7° (P < 0.001), and the mean congruence angle decreased from 24.9° to 4.3° (P < 0.001). At 2 years follow up, all KOOS subscales had improved: pain (92.0 ± 12.9), symptoms (90.2 ± 11.9), activities of daily living (95.7 ± 7.3), sports activity (85.7 ± 16.9), quality of life (87.7 ± 12.9), and patellofemoral (89.0 ± 9.6) outcomes. KOOS subscale scores improved regardless of the preoperative TT-TG distance (21.1 ± 3.5 mm; range, 13.8–29.9 mm).ConclusionsMPFL reconstruction using FiberTape and knotless SwiveLock anchors was performed without sacrificing autologous tissue. No recurrent patellar dislocation was observed during the 2-year follow up period. All KOOS subscale scores improved using FiberTape and SwiveLock anchors in MPFL reconstruction.     

Lateral patellar maltracking due to trochlear dysplasia: A computational study

BackgroundThe study focuses on the influence of trochlear dysplasia on patellar tracking related to patellar instability.MethodsKnee extension against gravity and dual-limb squatting were simulated with seven models representing knees being treated for recurrent instability. Trochlear depth was altered to represent lateral trochlear inclination (LTI) values of 6°, 12° and 24°. Repeated measures analyses compared patellar lateral shift (bisect offset index) across different LTI values. Peak bisect offset index during extension and squatting was correlated with patella alta (Caton–Deschamps index) and maximum lateral position of the tibial tuberosity.ResultsBisect offset index varied significantly (p < 0.05) between different LTI values at multiple flexion angles throughout simulated knee extension and squatting. Average bisect offset values were 1.02, 0.95, and 0.86 for LTI = 6°, 12°, and 24°, respectively, at 0° of flexion for knee extension. The strongest correlation occurred between peak bisect offset index and lateral position of the tibial tuberosity for knee squatting with LTI = 6° (r² = 0.81, p = 0.006). The strength of the correlation decreased as LTI increased. Caton–Deschamps was only significantly correlated with patellar tracking for LTI = 24° during knee squatting.ConclusionsA shallow trochlear groove increases lateral patellar maltracking. A lateral tibial tuberosity in combination with trochlear dysplasia increases lateral patellar tracking and the risk of patellar instability. Patella alta has relatively little influence on patellar tracking in combination with trochlear dysplasia due to the limited articular constraint provided by the trochlear groove.     

Medial closing-wedge distal femoral varus osteotomy: Symptoms and functional impact in cases of associated patellofemoral osteoarthritis. A two-year follow-up prospective pilot study

PurposeTo date, indications for distal femoral varus osteotomy (FVO) in cases of associated patellofemoral osteoarthritis (PFO) have yet to be clarified. The purpose of this prospective study is to assess the short-term symptoms, functional and radiological impact of a medial closing-wedge femoral varus osteotomy on the patellofemoral joint in patients with valgus deformities who are afflicted with lateral tibiofemoral osteoarthritis (LTFO) associated with PFO.MethodsFourteen patients (15 knees) received a medial closing-wedge femoral varus osteotomy. The functional impact of an FVO on the patellofemoral joint was assessed based on the KOOS-PF (Knee Injury and Osteoarthritis Outcome Score-Patellofemoral Subscale), the Kujala score and the patellofemoral symptoms. Realignment of the patella was measured by the Merchant's patellofemoral congruence angle. The pre- and post-operative symptoms and functional scores were compiled prospectively and compared two years after the surgery.ResultsThe Kujala patellofemoral functional scores and the KOOS-PF showed considerable improvement with a differential of + 37.5 points ± 20.4 and + 42.7 points ± 19.3 (p < .01) respectively. The average Merchant's congruence angle went from 8.8° laterally to 3.6° medially, resulting in medialization of the patella, with a significant difference (p < .01). Based on the specific clinical analysis of the patellar joint, preoperative J-sign was identified in 26.7% of patients (n = 4) and was not found during postoperative examination (p = .1). Preoperative apprehension test was identified in 33.3% of patients (n = 5) against 13.3% (n = 2) after surgery (p = .39). Preoperative pain extension test was identified in 40% of patients (n = 6) against 20% during postoperative clinical analysis (p = .43).DiscussionAlthough the threshold of significance for patellofemoral symptoms was not reached, the medial closing-wedge femoral varus osteotomy induces a significant medialization of the patella (Merchant's congruence angle) and improves short-term functional results even with co-existing patellofemoral osteoarthritis. Due to the lack of specificity of the patellofemoral scores, patellofemoral osteoarthritis improvement is difficult to determine on its own, but does not represent a contraindication to FVO.Level of evidenceIII. Prospective clinical study.     

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