Tibial tubercle proximalization as quadriceps lengthening in treating severe habitual patellar dislocation in adults

BackgroundTo describe a novel ‘four-in-one’ procedure – including tibial tubercle proximalization, extensive lateral release, tibial tubercle medialization, and medial patellofemoral ligament reconstruction – for treating severe habitual patellar dislocation (HPD) in adults, and to report its early clinical outcomes.MethodsThirteen patients (13 knees) with severe primary HPD received this procedure. Results of the physical examinations, including apprehension tests and patellar tracking throughout full range of motion, were recorded pre-operatively and at final follow-up. Radiological assessments included standard anteroposterior view, true lateral view at 30° knee flexion, axial views of the patellofemoral joint at both 30° and maximum angle of knee flexion, and computed tomography scans at full knee extension pre-operatively and at final follow-up. Subjective patellofemoral functions were evaluated with the Kujala functional score before the index procedure and at final follow-up visit.ResultsAll 13 patients were followed for an average period of 35.5 months (range, 25–49). After the index ‘four-in-one’ procedure no patient reported reoccurrence of patellar dislocation at the final follow-up visit. Radiographically, there was a statistically significant improvement in the congruence angle from 75.2 ± 16.3° pre-operatively to ? 7.2 ± 5.4° postoperatively (P < 0.01) and in the lateral patellofemoral angle from ? 66.3 ± 8.3° pre-operatively to 6.3 ± 2.6° postoperatively (P < 0.01). The average pre-operative Kujala functional score was 41.4 and average postoperative score was 94.9 (P < 0.05).ConclusionThe novel ‘four-in-one’ procedure effectively treated HPD in adults with severe quadriceps contracture.     

Anteroposterior distance between the tibial tuberosity and trochlear groove in patients with patellar instability

BackgroundOur objective was to describe a measurement to assess sagittal tibial tuberosity (TT)–trochlear groove (TG) distance and to compare this between asymptomatic (control) patients and patients with symptomatic patellar instability.MethodsWe compared static CT images of 22 fully extended knees of patients with symptomatic patellar instability with images of 22 asymptomatic knees. TT–TG distance was measured to quantify lateralization of the TT, and anteroposterior TT–TG distance was used to quantify the sagittal distance between these two points. Lateral trochlear inclination, sulcus angle, and trochlear depth were measured. Groups were compared using paired t tests (alpha = 0.05). Correlations of anteroposterior TT–TG distance with lateral trochlear inclination, sulcus angle, and trochlear depth were assessed using linear and multivariate regression.ResultsMean TT–TG distances were 19.9 ± 4.4 mm (symptomatic) and 16.8 ± 5.5 mm (control) (mean ± std deviation) (P = 0.002). Mean anteroposterior TT–TG distances were 8.3 ± 7.8 mm (symptomatic) and ? 0.5 ± 4.6 mm (control) (P < 0.0001). The symptomatic group had greater measurements of trochlear dysplasia, with lower lateral trochlear inclination, greater sulcus angle, and lower trochlear depth (all P < 0.0001). Anteroposterior TT–TG distance and trochlear depth were strongly negatively correlated (r = 0.62, R² = 0.39, P < 0.0001).ConclusionsIn asymptomatic patients, the anteroposterior TT–TG distance was ? 0.5 mm, indicating that the TG and TT were nearly in the same coronal plane. In patients with symptomatic patellar instability, the TG was almost nine millimeters anterior, and this distance correlated with measurements of trochlear dysplasia.Level of evidenceIII, case control study.     

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.     

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.     

Recurrent patellar dislocations with patellar cartilage defects: A pain in the knee?

BackgroundRecurrent patellar dislocation in combination with cartilage injures are difficult injuries to treat with confounding pathways of treatment. The aim of this study was to compare the clinical and functional outcomes of patients operated for patellofemoral instability with and without cartilage defects.MethodsEighty-two patients (mean age 28.8 years) with recurrent patellar dislocations, who underwent soft-tissue or bony procedures, were divided into two matched groups (age, sex, follow up and type of procedure) of 41 each, based on the presence or absence of cartilage defects in patella. Chondroplasty, microfracture, osteochondral fixation or autologous matrix-induced chondrogenesis (AMIC)-type procedures were performed depending on the nature of cartilage injury. Lysholm, Kujala, Tegner and Subjective Knee scores of both groups were compared and analysed. Complications and return to surgery were noted.ResultsWith a mean follow up of 8 years, there was a significant improvement observed in all the mean postoperative patient-reported outcome measures of both groups, as compared with the preoperative scores (P < 0.05). Comparing the two groups, postoperative Lysholm, Kujala and Subjective knee scores were significantly higher in patients operated without cartilage defects (P < 0.05). Three patients operated for patellofemoral instability with cartilage defects underwent patellofemoral replacement subsequently. The odds ratio for developing complications was 2.53 for patients operated with cartilage defects.ConclusionAlthough there is a significant improvement in the long-term outcome scores of patients operated for recurrent patellar dislocation with cartilage defects, the results are significantly inferior compared with those without cartilage defects, along with a higher risk of developing complications and returning to surgery.     

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     

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....     

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。     

Trochleoplasty for severe trochlear dysplasia significantly improves the quality of life of patients with symptomatic patellar instability

BackgroundTrochleoplasty is a recognized surgical technique to address severe trochlear dysplasia. The clinical and radiological outcomes of trochleoplasty surgery in trochlear dysplasia have been well reported. There is a paucity in literature regarding the correlation between trochleoplasty and quality of life (QoL). The aim of this study is to measure the improvement in QoL, in patients with severe trochlear dysplasia and recurrent patellar instability following trochleoplasty.MethodsBetween 2013 and 2019, 51 trochleoplasty cases were performed in 48 patients. They were identified from our prospectively kept database. All operations were performed by a fellowship trained consultant sports knee surgeon. Functional outcomes and QoL scores were assessed using Kujala, IKDC and EQ-5D index. Objective outcomes were obtained following each patient’s latest follow-up assessment.ResultsThe mean age at operation was 22y (SD ± 4.7, range 14–37y) and the mean follow-up period was 21.6 months (SD ± 15.2, range 12–60 months). The mean Kujala score improved from 58.1 (SD 14.9) to 77.9 (SD 17.3) at latest follow-up (p < 0.001). The mean IKDC score improved from 40.5 (SD 14.2) to 69.5 (SD 22.8) at latest follow up (p < 0.001). The mean EQ-5D index also improved from 0.593 (SD 0.257) to 0.824 (SD 0.189) at latest follow-up (p = 0.003). A higher Body Mass Index (BMI; >30 kg/m²) was associated with inferior outcomes.ConclusionTrochleoplasty is an effective surgical technique which improves the QoL in patients suffering from patellar instability secondary to severe trochlear dysplasia. BMI can be used to predict post-operative outcomes.     

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.     

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.     

Phenomenon of painless knee in recurrent patellar dislocation in children

Introduction

Cartilage lesion with patellar malalignment may be correlated with pain. Situations in which patients with recurrent patellar dislocation are painless between episodes of luxation can be approached with considerable curiosity. We evaluated the distribution of substance-P and S-100 protein expression in soft tissue of the knee in children with recurrent patellar dislocation, in order to evaluate the distribution of nociceptors and determine tissue origins of this situation.

Material and methods

Samples were collected from the medial and lateral synovial membrane, medial and lateral patellar retinaculum, Hoffa''s body, patellar ligament, and quadriceps’ aponeurosis in 10 children during the Blauth procedure and 10 adults with idiopathic osteoarthritis during total joint alloplasty. The density of nociceptive fibres was compared in the children and adults using S-100 and substance-P monoclonal antibodies.

Results

Statistical differences between groups were demonstrated for S-100 expression in synovial membrane of the medial knee compartment (p < 0.05) and for substance-P expression in the medial patellar retinaculum (p < 0.05) and synovial membrane of the lateral (p < 0.05) and medial (p < 0.05) knee compartment in favour of children.

Conclusions

Lack of pain sensations in patients with recurrent patellar dislocation may be associated with non-increased expression of nerve endings in Hoffa''s body. Increased expression of either S-100 protein or substance-P in synovial membrane and the medial retinaculum did not induce pain development in the knee joints of that group of patients.     

Long-term results of arthroscopic medial reefing for patellar instability

BackgroundThe purpose of the study was to investigate the long-term outcomes of the all-inside arthroscopic medial reefing (AAMR) procedure for patellar instability and the factors that affect successful outcome.MethodsIn this retrospective study, AAMR with suture was performed in 16 knees of 15 patients who had at least one patellar dislocation and did not experience a decrease in pain and who did not have a major radiological bony abnormality. Preoperatively, Tegner and Lysholm scales were used; for the final evaluation Tegner, Lysholm, Kujala and Knee injury and Osteoarthritis Outcome Score (KOOS) were used.ResultsThe average age of the patients at the time of operation was 18 years (range: 11–36 years). The average follow-up time was 118.3 months (range: 85–143 months). Six of the 16 knees (37.5%) exhibited re-dislocation. Preoperatively, the mean Lysholm and Tegner were 66.5 and 4.0, respectively; and postoperatively increased to 89.3 (P = .001) and 4.66, respectively. At the final follow-up, mean Kujala was 89.3 (good), and mean KOOS was 91.4. In all patients with re-dislocation, fewer than four knots were used, and none of the patients with four knots exhibited re-dislocation. Re-dislocations occurred in two, two, one and one patients at two, three, five and eight years, respectively.ConclusionsThe AAMR technique is associated with minimal incisional scarring and an increase in functional scores. It is also associated with a high risk of re-dislocation compared with other methods. If the technique still needs to be used, despite the high re-dislocation rate, at least four knots should be applied.     

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.     

Femoral trochlear dysplasia after patellar dislocation in rabbits

BackgroundThe aim of this study was to investigate the effects of patellar dislocation on the development of the trochlear groove in rabbits.MethodsEighty knees from forty one-month-old white rabbits were divided into three groups (sham surgery, experimental, control). Lateral patellar dislocation was established in the experimental group and the effect on the development of the trochlear groove was compared with that in the sham surgery and control groups. Computed tomography (CT) scans were conducted to measure the angle, width and depth of the trochlear groove one month and six months after surgery. Gross specimen examination, cross-sectional anatomy and histological observation were conducted to investigate the anatomical configuration of the femoral trochlea and the changes in cartilage tissue of the trochlear groove at six months after surgery.ResultsAt six months after surgery, CT scans showed a significant difference between the sham surgery group and the experimental group in the angle, width and depth of the trochlear groove. There were no significant differences between the sham surgery group and the control group. Gross specimen examination and cross-sectional anatomy indicated low lateral femoral trochlea and reduced height at the trochlear groove in the experimental group. The femoral trochlea was of normal appearance in the other two groups. Histological investigations showed that there were degenerative changes in the cartilage tissue of the femoral trochlea in the experimental group.ConclusionsSecondary femoral trochlear dysplasia may be caused by patellar dislocation in a normally developing femoral trochlea. Patellar dislocation may be one of the causes of femoral trochlear dysplasia.     

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.     

The Forgotten Joint Score-12 as a valuable patient-reported outcome measure for patients after first-time patellar dislocation

BackgroundThe aim of this study is to assess joint awareness after first-time patellar dislocation using the Forgotten Joint Score-12 (FJS-12) and to compare performance of this measurement tool to acknowledged patient-reported outcome scores.MethodsA retrospective analysis of patients with confirmed first-time patellar dislocation was performed. Patients were assessed with the FJS-12, the Kujala and the WOMAC scores. Reference values for the FJS-12 were obtained from a matched healthy control group with no history of previous knee joint pathology. We calculated Cronbach's alpha, assessed the ceiling effect for all scores, and calculated the Spearman correlation coefficient between themResultsFifty-six patients (mean follow-up 8.2 years, range 1.6–14.1) with a mean age of 26.4 years were analysed. Compared with the age- and gender-matched control group, the patellar dislocation group showed significantly lower (worse) mean FJS-12 scores (88 vs. 71, P < 0.001). Inter-score correlation between the FJS-12 and the Kujala was high (r = 0.74) and significant (P < 0.001), as well as between FJS-12 and WOMAC (r = 0.81, P < 0.001). Cronbach's alpha of the FJS-12 was 0.92 (95% confidence interval 0.90–0.94). The FJS-12 showed less ceiling effect (16%) compared with the Kujala score (23%) and the WOMAC score (32%).ConclusionsThe concept of joint awareness has been successfully applied to a patient population after patellar dislocation. The FJS-12 showed less ceiling effect compared with the Kujala and the WOMAC scores, suggesting the score was able to capture subtle knee problems in patients after patellar dislocation     

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.     

早期手术治疗急性创伤性髌骨脱位疗效分析

目的探讨早期手术治疗急性创伤性髌骨脱位的效果。方法对22例急性创伤性髌骨脱位患者行关节镜下内侧髌骨股骨韧带（MPFL）修补或重建,同时部分病例行关节镜下髌外侧支持带松解和（或）胫骨结节内移截骨。结果术后平均随访25.5个月,术后所有病例均未出现髌骨再次脱位,无髌骨错动或半脱位。患者主观Kujala评分、Lysholm评分、Tegner运动等级评分与受伤前比较差异无统计学意义（P〉0.05）。结论早期手术治疗急性创伤性髌骨脱位能够明显改善髌骨稳定性,患者的术后主观评分和运动等级均能够达到受伤前水平,对于患者术后膝关节功能和运动水平的恢复有积极的作用。     

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.