Midterm results of comprehensive surgical reconstruction including sulcus-deepening trochleoplasty in recurrent patellar dislocations with high-grade trochlear dysplasia

Trochleoplasty Provides Good Outcomes for Recurrent Patellofemoral Dislocations with No Clear Superiority across Different Techniques

Background: Literature is sparse on outcome comparisons between different trochleoplasty techniques in the treatment of patella instability. To date, it is unclear whether there is a technique that offers superior outcomes. This systematic review and meta-analysis aims to compare and evaluate the outcomes of trochleoplasty techniques in the treatment of patellofemoral instability in trochlea dysplasia to establish whether there is an ideal choice of trochleoplasty technique for superior outcomes. Methods: 21 studies involving 880 knees were included. The mean age of the patients was 21.7 years (range 8-49 years). Mean follow-up timeframe of 43.5 months (range 8.8-100 months). Clinical outcomes assessed included rates of recurrence of patellofemoral dislocation, patient satisfaction, Kujala score, International Knee Documentation Committee (IKDC) score, Tegner score, and Lysholm score. Egger's test showed no publication bias across all outcomes assessed. Results: Favourable results were seen across all outcomes assessed and patient satisfaction. Improvements were seen with Kujala, IKDC, and Lysholm scores. Tegner scores showed good return to function. Post-operative dislocation and complication rates were low across the different techniques. Meta-regression for Kujala and IKDC scores showed good outcomes regardless of trochleoplasty technique used (Kujala, p = 0.549, relative risk 492.06; IKDC, p = 0.193, RR 0.001). The exact risk that trochleoplasty poses to the cartilage remains uncertain, as no study had a conservatively managed arm for comparison. Conclusions: Trochleoplasty yielded good outcomes irrespective of technique used with no clear superiority demonstrated in any technique in terms of outcome scores, satisfaction, post-operative dislocation rates or complications.

No significant difference in thick versus thin osteochondral flap trochleoplasty in the treatment of trochlear dysplasia: A systematic review

PURPOSE

Trochleoplasty has become increasingly utilised to address patellar instability in the setting of severe trochlear dysplasia. There remains a paucity of literature on the outcomes of 'thick'- versus 'thin'-osteochondral flap trochleoplasty. The purpose of this study is to compare clinical and radiographic outcomes between patients with patellar instability with symptomatic trochlear dysplasia treated using a 'thick' versus 'thin' osteochondral flap trochleoplasty.

METHODS

A systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using a PRISMA checklist. Quality assessment of final articles was conducted by two blinded reviewers. Articles were separated based on the use of a 'thick' versus 'thin' flap trochleoplasty. Data collection consisted of recording the following variables: patient demographics, indications for trochleoplasty, mean follow-up time, additional procedures performed during trochleoplasty, patient-reported outcome measures (PROMs), radiographic outcomes (tibial tubercle-trochlear groove [TT-TG] distance, Caton-Deschamps Index [CDI] and sulcus angle [SA]) and the incidence of any postoperative complications and patellar redislocation rates.

RESULTS

A total of 24 studies, consisting of 927 patients, were identified as meeting inclusion criteria. A total of five papers described a 'thick' flap technique, while 19 papers described the use of a 'thin' flap technique. No significant difference in the mean improvement of Kujala scores was appreciated when comparing 'thick' versus 'thin' techniques (p > 0.05). Improvements in mean radiographic outcomes based on TT-TG, CDI and SA were observed in both 'thick' and 'thin' flap trochleoplasty groups. The overall redislocation rate was 0.35%.

CONCLUSION

No significant difference in Kujala scores was observed in patients undergoing trochleoplasty utilising 'thick' versus 'thin' technique, while improvements in mean TT-TG, CDI and SA were noted in both technique groups, with an overall redislocation rate of 0.35%.

LEVEL OF EVIDENCE

Level IV.

Derotational distal femur osteotomy with medial patellofemoral ligament reconstruction can get good outcomes in the treatment of recurrent patellar dislocation with excessive TT-TG and increased femoral anteversion

Background

Surgery is the main treatment for recurrent patellar dislocation (PD). However, due to the complexity of anatomical factors, there is still a lack of consensus on the choice of combined surgical methods. This study aimed to compare the clinical and radiological outcomes of medial patellofemoral ligament reconstruction combined with derotational distal femur osteotomies (MPFLR + DDFO) and combined with tibial tubercle osteotomies (MPFLR + TTO) for recurrent PD with increased femoral anteversion angles (FAA) and excessive tibial tubercle-trochlear groove (TT-TG) distance.

Methods

In this retrospective analysis, MPFLR + DDFO and MPFLR + TTO patients from 2015 to 2020 were included. Group A (MPFLR + DDFO, n = 42) and B (MPFLR + TTO, n = 46) were formed. Clinical outcomes included physical examinations, functional outcomes (Kujala, Lysholm, International Knee Documentation Committee (IKDC), visual analog scale (VAS) and intermittent and persistent osteoarthritis pain scale (ICOAP), Tegner scores), and complications. The Caton-Deschamps index (CD-I), patellar title angle, patellar congruence angle, patella-trochlear groove distance, TT-TG distance, and FAA were used to assess radiological outcomes.

Results

All clinical outcomes improved significantly in both groups, but Group A had significantly better postoperative scores than Group B (Kujala: 89.8 ± 6.4 vs. 82.9 ± 7.4, P < 0.01; Lysholm: 90.9 ± 5.1 vs. 81.3 ± 6.3, P = 0.02; IKDC: 87.3 ± 9.0 vs. 82.7 ± 8.0, P < 0.01; Tegner: 6.0 (5.0, 9.0) vs. 5.0 (4.0, 8.0), P = 0.01). However, there was no significant difference in the VAS and ICOAP scores between the two groups. No dislocation recurrences occurred. Radiological outcomes improved significantly in both groups, but Group A had better outcomes. After surgery, the patellar height of 88.5% (23/26) patients in Group A and 82.8% (24/29) patients in Group B was restored to normal (the Caton-Deschamps index <1.2).

Conclusions

Both MPFLR + TTO and MPFLR + DDFO obtained satisfactory clinical and radiological outcomes in the treatment of recurrent PD with increased FAA and excessive TT-TG. However, the outcomes of MPFLR + DDFO were better and should be considered a priority. MPFLR + TTO may be not necessary for such patients.

Varus osteotomy as a salvage procedure for young patients with symptomatic patellofemoral arthritis and valgus malalignment at short- to mid-term follow-up: a case series

PURPOSE

The purpose of the study was to report the clinical, functional and radiological outcome following varus osteotomy as a salvage procedure in young to middle-aged patients with patellofemoral arthritis (PFA) and associated valgus malalignment. It was hypothesized that a significant improvement in knee function and reduction in pain would be achieved. Moreover, no conversion to patellofemoral joint arthroplasty could be observed.

MATERIAL AND METHODS

Patients (< 50 years of age) that underwent varus osteotomy between 08/2012 and 01/2020 for the treatment of symptomatic PFA and associated valgus malalignment were consecutively included (minimum follow-up: 24 months). Patient-reported outcome measures (PROM; International Knee Documentation Committee subjective knee form [IKDC]), Visual Analog Scale [VAS] for pain, Tegner Activity Scale [TAS], and satisfaction with the postoperative results (1-10-scale, 10 = highest satisfaction) and weight-bearing whole-leg anteroposterior radiographs were conducted pre- and postoperatively. The change in PROM and femorotibial angle (FTA) were tested for statistical significance.

RESULTS

In total, 12 patients (14 knees) were included (66.7% female; mean age: 33.8 ± SD 6.6 years). In ten cases, lateral opening-wedge distal femoral osteotomies (DFO) were performed, of which three cases included a concomitant femoral derotation. Three medial closing-wedge DFO and one medial closing-wedge high tibial osteotomy were performed. At follow-up (55.3 ± 29.3 months), a significant improvement in knee function (IKDC: 56.4 ± 14.4 to 69.1 ± 11.2, p = 0.015) and reduction in pain (VAS for pain: 3.5 [interquartile range 2.3-5.8] to 0.5 [0-2.0], p = 0.018) were observed. Patients were able to reach their preoperative sporting activity level (TAS: 3.0 [3.0-4.0] to 3.5 [3.0-4.0], p = 0.854) and were highly satisfied with the postoperative result (9.0 [6.5-10]). Additionally, a significant correction of valgus malalignment was observed (5.0° ± 2.9° valgus to 0.7° ± 3.2° varus, p < 0.001). Regarding complications, two re-osteosyntheses were performed due to loss of correction and delayed union. No conversion to patellofemoral arthroplasty occurred.

CONCLUSION

In patients with symptomatic PFA and associated valgus malalignment, varus osteotomy as a salvage procedure achieved a significant improvement in knee function and reduction in pain. No conversion to patellofemoral joint arthroplasty occurred at short- to mid-term follow-up.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

Medial Closing-Wedge Patellar Osteotomy in Patients With Patellofemoral Instability

Trochlear dysplasia is the main anatomical risk factor for objective patellar instability. Surgical correction of trochlea dysplasia via a trochleoplasty has been described with good clinical results reported. Concerns remain for who have abnormal patellofemoral tracking post a trochleoplasty due to incongruence between the two articulating surfaces. We described a medial closing wedge patellar osteotomy to improve congruency of the patellofemoral joint post-trochleoplasty.

Sulcus-Deepening Trochleoplasty for High-Grade Trochlear Dysplasia: Demystifying the Procedure-a Review of the Current Literature

PURPOSE OF REVIEW

The most common and biomechanically influential pathoanatomic risk factor for recurrent patellofemoral instability is trochlear dysplasia. Sulcus-deepening trochleoplasty is a procedure developed to address high-grade trochlear dysplasia in the setting of patellofemoral instability. The purpose of this paper is to outline the current classification and surgical management of trochlear dysplasia as well as to review the current literature on the clinical outcomes and complications of sulcus-deepening trochleoplasty.

RECENT FINDINGS

This review outlines the most recent literature reporting evidence behind the decision-making to perform a trochleoplasty in the setting of patellofemoral instability and high-grade trochlear dysplasia. Critical parameters include grade of trochlear dysplasia, severity of symptoms, pertinent physical examination findings, surgical techniques, modifications for skeletally immature patients, and considerations for the revision setting. Historic studies have elicited concerns regarding high reported complication rates for trochleoplasty; however, recent studies consistently report good clinical outcomes and acceptable complication rates, similar to those of other patellar stabilizing procedures. The addition of a trochleoplasty in patients with high-grade dysplasia results in a lower re-dislocation rate, significant improvements in patient-reported outcome measures (PROMs) as well as high levels of patient satisfaction and return to sport. The use of sulcus-deepening trochleoplasty for the treatment of high-grade dysplasia and recurrent patellofemoral instability is a well-established technique with good outcomes and an acceptable complication profile. In patients with high-grade dysplasia, trochleoplasty results in lower re-dislocation rates, high patient satisfaction scores, and good clinical and functional outcomes. An understanding of trochleoplasty and its indications should be in the armamentarium of surgeons treating patellofemoral instability.

Is the patella apprehension test a valid diagnostic test for patellar instability? A systematic review

Introduction

Patellar instability can arise from a traumatic event with anatomical predisposing factors increasing the risk of dislocation. Accurate diagnosis is required to initiate appropriate treatment. We aimed to evaluate the patella apprehension test (PAT) as a method to diagnose patellar instability.

Methods

The PRISMA diagnostic test accuracy checklist was followed. The review protocol was registered on PROSPERO with registration number CRD42022357898. Electronic databases, currently registered studies, conference proceedings and the reference lists of included studies were searched. A narrative synthesis evaluated the validity of the PAT as a method of diagnosing patellar instability.

Results

A total of 4867 records were screened in the initial search. Of these, 34 articles satisfied the inclusion criteria, assessing 1139 knees of 1046 patients. The PAT was found to have a high sensitivity and specificity. Its intra and inter-rater reliability was highly variable among studies. Studies reporting patellar instability correction following surgery also found a decrease in the number of patients exhibiting a positive PAT.

Conclusion

Current evidence suggests that the PAT has a high sensitivity and specificity. The intra- and inter-rater validities of the PAT are widely variable due to its subjective nature. Thus, though the PAT can be used to provide a provisional clinical diagnosis of patellar instability, formal functional assessment and imaging should be performed to confirm the diagnosis. Further research should explore the association between a positive PAT and anatomical parameters. In addition, studies comparing the accuracy of the PAT and radiological investigations should be performed.

Trochlear Shape and Patient-Reported Outcomes After Arthroscopic Deepening Trochleoplasty and Medial Patellofemoral Ligament Reconstruction: A Retrospective Cohort Study Including MRI Assessments of the Trochlear Groove

Background

Sparse objective data are available documenting changes of trochlear shape after trochleoplasty.

Purpose/Hypothesis

The purpose was to investigate whether standardized magnetic resonance imaging (MRI) measurements that characterize trochlear dysplasia (TD) change significantly after arthroscopic deepening trochleoplasty (ADT) combined with medial patellofemoral ligament (MPFL) reconstruction. It was hypothesized that MRI measurements would approximate normal values.

Study Design

Case series; Level of evidence, 4.

Methods

Patients who underwent ADT between October 2014 and December 2017 were considered for this study. The preoperative inclusion criteria for ADT surgery were patellar instability, a dynamic patellar apprehension sign at 45° of flexion, a lateral trochlear inclination (LTI) angle of <11°, and failed physical therapy. MRI was performed pre- and postoperatively, and standardized MRI measurements were calculated: LTI angle, trochlear depth, trochlear facet asymmetry, cartilage thickness, and trochlear height. The Banff Patella Instability Instrument 2.0 (BPII) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Kujala score were obtained pre- and postoperatively.

Results

A total of 16 knees in 15 patients (12 female and 3 male; median age, 20.9 years; range, 14.1-51.3 years) were evaluated. The mean follow-up time was 63.6 months (range, 23-97 months). The median LTI angle improved from 1.25° (range, -25.1° to 10.6°) preoperatively to 10.7° (range, -17.7° to 25.8°) postoperatively (P < .001), trochlear depth increased from 0.0 mm (range, -4.2 to 1.8 mm) to 3.23 mm (range, 0.25-5.3 mm) (P < .001), and trochlear facet asymmetry improved from 4.55% (range, 0.0%-28.6%) to 17.8% (range, 0.0%-55.6%) (P < .003). Cartilage thickness was unchanged: 4.5 mm (range, 1.9-7.4 mm) preoperatively and 4.9 mm (range, 0.6-8.3 mm) postoperatively (P = .796). BPII, KOOS, and Kujala scores improved significantly (P < .0034 for all).

Conclusion

Combined ADT and MPFL reconstruction led to statistically significant and clinically relevant improvements in patient-reported outcomes and standardized MRI measurements that characterize TD. The improvements corresponded to those obtained by open trochleoplasty. No significant reduction in cartilage thickness was seen.

3D Printed Models of Trochlear Dysplasia and Trochleoplasty Simulation for Trainee Education

Trochlear dysplasia is a major contributor to patellofemoral instability and subsequent failure of isolated soft tissue reconstruction procedures in the treatment of recurrent patellar dislocation and/or subluxation. Trochleoplasty procedures aim to address abnormal osseous trochlear morphologic factors that contribute to patellar maltracking. However, teaching these techniques is limited by the lack of reliable training models for trochlear dysplasia and trochleoplasty simulation. Although a cadaveric knee model of trochlear dysplasia for trochleoplasty simulation has been recently described, cadaveric knees are less amenable for use in trochleoplasty planning and surgeon training because of the absence of reliable, natural dysplastic anatomic relationships, such as suprapatellar spurs due to the rarity of dysplastic cadavers and the high cost of cadaveric specimens. Furthermore, readily available sawbone models represent "normal" osseous trochlear morphology and are difficult to modify and bend due to their material composition. Given this, we have developed a cost-effective, reliable, and anatomically accurate three-dimensional (3D) knee model of trochlear dysplasia for trochleoplasty simulation and trainee education.

Grooveplasty Compared With Trochleoplasty for the Treatment of Trochlear Dysplasia in the Setting of Patellar Instability

Purpose

To compare the clinical efficacy in the resolution of patellar instability, patient-reported outcomes (PROs), and complication and reoperation rates between patients who underwent grooveplasty (proximal trochleoplasty) and patients who underwent trochleoplasty as part of a combined patellofemoral stabilization procedure.

Methods

A retrospective chart review was performed to identify a cohort of patients who underwent grooveplasty and a cohort who underwent trochleoplasty at the time of patellar stabilization. Complications, reoperations, and PRO scores (Tegner, Kujala, and International Knee Documentation Committee scores) were collected at final follow-up. The Kruskal-Wallis test and Fisher exact test were performed when appropriate, and P < .05 was considered significant.

Results

Overall, 17 grooveplasty patients (18 knees) and 15 trochleoplasty patients (15 knees) were included. Seventy-nine percent of patients were female, and the average follow-up period was 3.9 years. The mean age at first dislocation was 11.8 years overall; most patients (65%) had more than 10 lifetime instability events and 76% of patients underwent prior knee-stabilizing procedures. Trochlear dysplasia (Dejour classification) was similar between cohorts. Patients who underwent grooveplasty had a higher activity level (P = .007) and a higher degree of patellar facet chondromalacia (P = .008) at baseline. At final follow-up, no patients had recurrent symptomatic instability after grooveplasty compared with 5 patients in the trochleoplasty cohort (P = .013). There were no differences in postoperative International Knee Documentation Committee scores (P = .870), Kujala scores (P = .059), or Tegner scores (P = .052). Additionally, there were no differences in complication rates (17% in grooveplasty cohort vs 13% in trochleoplasty cohort, P > .999) or reoperation rates (22% vs 13%, P = .665).

Conclusions

Proximal trochlear reshaping and removal of the supratrochlear spur (grooveplasty) in patients with severe trochlear dysplasia may offer an alternative strategy to complete trochleoplasty for the treatment of trochlear dysplasia in complex cases of patellofemoral instability. Grooveplasty patients showed less recurrent instability and similar PROs and reoperation rates compared with trochleoplasty patients.

Level of Evidence

Level III, retrospective comparative study.

Good patient satisfaction with low complications rate after trochleoplasty in patellofemoral instability

PURPOSE

Trochlear dysplasia has been recognized as the most common factor in patients with patellofemoral dislocation. Trochleoplasty is a surgical procedure whose primary goal is to modify the femoral trochlea's abnormal shape in patients suffering from patellar instability, requiring good surgical skills, correct indication, and accurate patient information.

METHODS

The review aims to describe preoperative planning, patient selection, most common surgical techniques, and clinical results of trochleoplasty in patellar instability in a reproducible manner.

RESULTS

Trochleoplasty can be considered a general term to describe a group of different procedures that reduce trochlear dysplasia's impact on patellar instability, aiming to restore patella-trochlear congruency, remove the supratrochlear bump, allowed a new groove positioning and are generally associated with other procedures. Recent studies showed satisfactory long-term results with the restoration of patellar stability, improving radiological findings of patellofemoral instability.

CONCLUSION

Trochleoplasty is a technically demanding technique, requiring careful patient selection, detailed knowledge, and surgical skills to avoid severe complications. Good patient satisfaction with a low risk of significant complications such as patellofemoral arthritis has been revealed. In conclusion, trochleoplasty should be systematically included in the treatment of patellar dislocation, if indicated.

LEVEL OF EVIDENCE

V.

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

BACKGROUND

Trochleoplasty 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.

METHODS

Between 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.

RESULTS

The 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.

CONCLUSION

Trochleoplasty 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.

Return to Sports and Patients' Rehabilitation Continuum After Deepening Trochleoplasty and Concomitant Patellar-Stabilizing Procedures: A Case Series of 111 Patients at 2 to 4 Years of Follow-up

BACKGROUND

There are few reports on the return to sports after complex patellar-stabilizing surgery.

PURPOSES

To evaluate patients' ability to return to sports and to investigate the extent to which the preoperative level of sports participation influences sports activity after deepening trochleoplasty (TP) and concomitant patellar-stabilizing procedures.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between April 2015 and April 2019, 144 patellar-stabilizing procedures, including deepening TP and medial patellofemoral ligament reconstruction or medial reefing with and without concomitant realignment procedures, were carried out in 142 patients. The Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) and the Tegner activity score were used to assess patients' quality of life and sports activity level. In addition, a numerical analog scale was used to evaluate patellofemoral pain intensity during rest and activity and subjective knee joint function.

RESULTS

Outcomes were available for 111 patients (112 knees) (male/female, 77/34; mean age, 23.4 ± 7.8 years), yielding a 77.7% follow-up rate at a mean of 39.2 ± 9.9 months (range, 24-48 months). Two-thirds of the patients returned to their preoperative level of activity or higher, but their Tegner scores did not change significantly (4.5 ± 2.4 vs 4.7 ± 1.6; P = .365). Low-level athletes (preoperative Tegner score 0-4) participated at a higher level of sports activity (2.7 ± 1.4 to 4.1 ± 1.2; P < .0001), whereas higher-level athletes (preoperative Tegner score 5-10) participated at a lower level (6.8 ± 1.3 to 5.5 ± 1.7; P < .0001). The likelihood of returning to the preoperative activity level (Tegner score) was significantly higher in the low-level activity group than in the high-level activity group (P = .0001; 95% CI, 4.055-27.05; odds ratio, 10.47). All of the patient-reported outcome measures improved postoperatively, independent of the patients' age, sex, and body mass index.

CONCLUSION

Patients undergoing deepening TP and medial soft tissue stabilization with or without concomitant realignment surgery for complex patellar instability can expect good clinical results and a high rate of return to sports participation, with two-thirds of patients returning to their preoperative Tegner-level of activity or higher. However, higher-level athletes should be informed that their likelihood of returning to sports at the preoperative level or full participation at a competitive level is reduced.

Trochleoplasty: Indications in patellar dislocation with high-grade dysplasia. Surgical technique

Trochlear dysplasia consists in deficient trochlear concavity, giving rise to a flat or convex trochlea, and is the main risk factor for patellar dislocation. Surgical indications depend on familiarity with trochlear dysplasias, and especially those of high grade, identified on clinical examination and standard and cross-sectional imaging, and on quantification of associated instability factors. Treatment strategy is accordingly determined "à la carte" to correct these factors one by one. Sulcus deepening trochleoplasty corrects the morphology and is the appropriate etiological treatment. It gives good results in terms of recurrence of dislocation, but tends to cause knee stiffness and patellofemoral osteoarthritis. Indications are based on objective patellar instability associated to high-grade B or D dysplasia. Medial patellofemoral ligament reconstruction should be systematically associated. The lateral retinaculum is systematically sectioned, as patellar tilt is never reducible in such high-grade dysplasia. Trochleoplasty corrects the sulcus defect, resolves protrusion and enables proximal realignment. The main complications are stiffness and pain due to persistence or onset of cartilage lesions. Trochleoplasty is indicated: 1) in first line for objective patellar instability associated with high-grade dysplasia; or 2) for recurrence in high-grade dysplasia previously managed by other surgery. The aim of the present study was to review the literature on trochleoplasty and address the following questions: how to define high-grade dysplasia? What are the key clinical and radiologic points? What are the risk factors for patellar dislocation? What trochleoplasty techniques are available? What results can be expected? Level of evidence: V; expert opinion.

[Osteotomy in patellofemoral malalignment]

Anterior knee pain and patellofemoral instability are the two major symptoms of patellofemoral dysbalance. Various pathologies can cause these symptoms. In recent years, axis deviations have been increasingly discussed as a cause of patellofemoral dysbalance. In the frontal axis, valgus deformities are a major risk factor, but torsional deformities may be a cause as well. Increased femoral internal rotation or increased tibial external rotation are the key pathologies. Osteotomy is the treatment of choice. Valgus deformities require varisation osteotomy, which is either performed on the femur or tibia depending on the location of the deformity. Torsional deformities are treated by external femoral or internal tibial torsional osteotomy. Femoral osteotomies are located above the femoral condyles, tibial osteotomies above the tibial tuberosity. Tibial internal torsional correction must not exceed 15° because this would jeopardise structures such as the peroneal nerve. Rehabilitation includes partial weight-bearing for four to six weeks. Hardware removal can be performed half a year after osteotomy. The relevance of axis deviations and treatment by osteotomy in patellofemoral dysbalance has been highlighted in recent reviews. Several publications report promising results after osteotomy, including significant pain relief and achievement of patellofemoral stability.

Trochlear Dysplasia: When and How to Correct

When? Only patients with high-grade trochlear dysplasia types B and D, in which the prominence of the trochlea (supratrochlear spur) is over 5 mm, recurrent patellar dislocation, and maltracking. How? Sulcus deepening trochleoplasty: modifies the trochlear shape with a central groove and oblique medial and lateral facets; decreases the patellofemoral joint reaction force by reducing the trochlear prominence (spur); and reduces the tibial tubercle and the trochlear groove value by a proximal realignment. Pros: This procedure is highly effective in restoring patellofemoral stability and satisfying the patients. Cons: The patients must be aware of the risk of continuing residual pain and range-ofmotion limitation and that the development of patellofemoral osteoarthritis is not predictable.

Complications and outcomes of trochleoplasty for patellofemoral instability: A systematic review and meta-analysis of 1000 trochleoplasties

BACKGROUND

Trochleoplasty is an effective patellar stabilization procedure; however, it is associated with a risk of complications that cannot be ignored. Prior systematic reviews on this topic did not include more recent studies reporting important outcomes, particularly the long-term results of lateral elevation trochleoplasty. This led us to carry out a new meta-analysis of the various trochleoplasty procedures to specify: (1) the recurrence rate of patellofemoral dislocation; (2) the complication rates and; (3) the clinical outcomes.

PATIENTS AND METHODS

Studies reporting complications and clinical outcomes of trochleoplasty, whether or not it was combined with other procedures for patellofemoral instability, were identified in the MEDLINE, Embase, Scopus, Cochrane Library, Web of Science databases and by searching the grey literature. The primary endpoint was the recurrence of patellofemoral dislocation while the secondary endpoints were objective patellofemoral instability without dislocation, stiffness, patellofemoral osteoarthritis, subsequent surgeries and various clinical outcome scores. The results were combined in a random-effects model (weighing factor: inverse variance) when the heterogeneity was less than 80%.

RESULTS

Twenty-eight studies were included: 5 featured lateral elevation trochleoplasty, 10 about the Dejour deepening trochleoplasty, 12 about the Bereiter deepening trochleoplasty and 1 about the recession wedge trochleoplasty. A total of 1000 trochleoplasty procedures were done in 890 patients who had a follow-up of 1 to 25 years. There were 24 cases of recurrent dislocation (24/994 [2.4%]; this outcome was not reported for 6 trochleoplasties). The Dejour deepening trochleoplasty was the most effective with only 1 recurrence in 349 knees (0.28%). For the other complications, residual patellar instability without dislocation occurred in 82 of 754 knees (8% [95% CI: 3-14%]), patellofemoral osteoarthritis in 117 of 431 knees (27%), stiffness in 59 of 642 knees (7% [95% CI: 3-12%]) and the need for subsequent surgery in 151 of 904 knees (17%).

DISCUSSION

This study found a low recurrence rate for patellofemoral dislocation and residual instability. The incidence of stiffness, patellofemoral osteoarthritis and subsequent surgery remains high but differs greatly between studies. This meta-analysis showed a very large disparity between studies for most complications, which justifies the need for randomized and comparative studies to establish the role of trochleoplasty procedures in the treatment algorithm for patellar instability.

LEVEL OF EVIDENCE

IV; systematic review and meta-analysis.

Treatment of Proximal Trochlear Dysplasia in the Setting of Patellar Instability: An Arthroscopic Technique

Patellar instability is a complex disorder with multiple etiologies, and treatment must be individualized to the unique pathoanatomy of each patient. Medial patellofemoral ligament reconstruction is one of the most commonly performed procedures for the treatment of patellar instability. Patients with a symptomatic supratrochlear spur, defined by the presence of a "jumping" J sign on examination, also may benefit from an adjunctive proximal trochlear resection. Here, we describe a technique for an arthroscopic proximal trochlear resection, or "bumpectomy," involving resection of the supratrochlear spur. In appropriately indicated patients, we have found this procedure to be a useful adjunct to medial patellofemoral ligament reconstruction without the need for concurrent trochlear sulcus deepening.

Conservative versus tailored surgical treatment in patients with first time lateral patella dislocation: a randomized-controlled trial

Background

Patellar instability has a high incidence and occurs particularly in young and female patients. If the patella dislocates for the first time, treatment is usually conservative. However, this cautious approach carries the risk of recurrence and of secondary pathologies such as osteochondral fractures. Moreover, there is also risk of continuous symptoms apparent, as recurrent patella dislocation is related to patellofemoral osteoarthritis as well. An initial surgical treatment could possibly avoid these consequences of recurrent patella dislocation.

Methods

A prospective, randomized-controlled trial design is applied. Patients with unilateral first-time patella dislocation will be considered for participation. Study participants will be randomized to either conservative treatment or to a tailored patella stabilizing treatment. In the conservative group, patients will use a knee brace and will be prescribed outpatient physical therapy. The surgical treatment will be performed in a tailored manner, addressing the pathologic anatomy that predisposes to patella dislocation.

The Banff Patellofemoral Instability-Instrument 2.0, recurrence rate, apprehension test, joint degeneration, and the Patella Instability Severity Score will serve as outcome parameters. The main analysis will focus on the difference in change of the scores between the two groups within a 2-year follow-up.

Statistical analysis will use linear mixed models. Power analysis was done for the comparison of the two study arms at 2-year follow-up with regard to the BPII Score. A sample size of N = 64 per study arm (128 overall) provides 80% power (alpha = 0.05, two-tailed) to detect a difference of 0.5 standard deviations in a t-test for independent samples.

Discussion

Although several studies have already dealt with this issue, there is still no consensus on the ideal treatment concept for primary patellar dislocation. Moreover, most of these studies show a unified surgical group, which means that all patients were treated with the same surgical procedure. This is regarded as a major limitation as surgical treatment of patella dislocation should depend on the patient’s anatomic pathologies leading to patellar instability. To our knowledge, this is the first study investigating whether patients with primary patella dislocation are better treated conservatively or operatively with tailored surgery to stabilize the patella.

Trial registration

The study will be prospectively registered in the publicly accessible database www.ClinicalTrials.gov.

Surgery for patellar dislocation has evolved towards anatomical reconstructions with assessment and treatment of anatomical risk factors

PURPOSE

Increasing knowledge on the treatment of patellar dislocation has resulted in the development of new surgical techniques for patella stabilisation. National incidence and trends in surgery for patellar dislocation were examined using data from the Finnish National Hospital Discharge Register (NHDR). The hypothesis was that an increased understanding of the pathophysiology of patellar instability has increased the popularity of reconstructing damaged structures and modification of anatomical risk factors.

METHODS

Data from the years 1997-2016 were collected from the NHDR database using ICD-10 diagnostic codes and the Nomesco Classification of Surgical Procedures (NCSP) codes. Surgical procedures were categorised into subgroups representing the main surgical approaches of patellar dislocation. Total incidence of surgery for patellar dislocation and change in incidence during the study period were calculated.

RESULTS

A total of 9702 operations for patellar dislocation were performed during the study period. Median (IQR) patient age at time of primary surgery was 23 (18-34) years. The total incidence of surgeries remained stable across the study period at of 8.9 per 100,000 person-years. Incidences of ligament reconstruction, femoral osteotomies and osteochondral fragment reimplantation operations multiplied during the study period. Ligament reconstruction procedures were the most performed operations at the end of the study period.

CONCLUSION

The incidence of surgical procedures for patellar dislocation remained unchanged during the years 1997-2016. Ligament reconstruction procedures increased in popularity. Surgical techniques have shifted towards the reconstruction of damaged structures and the modification of congenital anatomical risk factors for patellar dislocation. Diversified surgical techniques have enabled the tailoring and combining of stabilizing procedures according to the patient's individual anatomy.

Age at surgery is correlated with pain scores following trochlear osteotomy in lateral patellar instability: a cross-sectional study of 113 cases

Background

A trochlear osteotomy aims to restore patellar stability in patients with recurrent patellar instability and trochlear dysplasia. The age of patients at time of surgery could be a relevant factor which influences outcome. We hypothesized that lower age at time of surgery is associated with better patient-reported outcomes.

Methods

A retrospective study was conducted on patients with patellar instability and trochlear dysplasia. Patients were contacted by phone for informed consent and were then asked to complete online patient-reported outcome measurements (PROMs). The PROMs consisted of the Kujala Knee Score (KKS) (Kujala et al., Arthroscopy 9(2):159-63, 1993; Kievit et al. Knee Surg Sports Traumatol Arthrosc. 21(11):2647-53, 2013), the Short Form 36-item health survey (SF-36v1) (Ware, Med Care 73-83, 1992; Aaronson et al., J Clin Epidemiol. 51(11):1055-68, 1998), and visual analog scale (VAS) scoring pain, instability, disability, and satisfaction on a 0–100 scale. Multivariable linear regression models were used to study the effect of age on the PROM scores.

Results

For this study, 125 surgical procedures in 113 patients were included. Mean VAS pain at rest was 19 and at activity 38; mean Kujala score was 73. Multivariable regression analysis revealed that age at the time of surgery was correlated with VAS pain at rest, with a 0.95 increase of VAS score (scale 0–100) for every year of age. Recurrence of instability was observed in 13 (10%) knees.

Conclusion

In this cross-sectional study, pain scores of 113 patients who have undergone a lateral facet elevating trochlear osteotomy for patellar instability were reported. Age at time of surgery was correlated with an increased pain score at rest with an average of 9.5 points (scale 0–100) for every 10 years of age. Age at time of surgery was not correlated with overall satisfaction.

Evaluation of recurrent dislocation of the patella in children with MRI: Goldthwait technique combined with lateral release, and VMO advancement-a retrospective study of 85 knees

PURPOSE

There are certain risk factors responsible for patella instability that should be identified before choosing the most appropriate treatment.

METHODS

We evaluated 83 skeletally immature patients who, after two or more patellar dislocation episodes, underwent surgical treatment to address the condition of patellar instability. Each patient was evaluated for patellar instability risk factors using the Balcarek patellar instability severity score. Evaluation of patellar instability included knee MRI to systematically identify anatomical risk factors. The preoperative and postoperative clinical evaluation included the modified Cincinnati score and the Kujala score. The Roux-Goldthwait technique combined with lateral retinaculum release and the advancement of the vastus medialis oblique (VMO) was performed on all knees.

RESULTS

The mean patient age at the time of surgery was 12.2 ± 1.59 years (range 8-14 years). The average follow-up was 4.72 ± 1.37 (range 3-8) years. Trochlear dysplasia (decreased trochlear depth), the most common anatomical risk factor, was identified in 71 knees (83.5%). The modified Cincinnati score increased from 58.46 ± 8.75 (range 49-76) points to 94.07 ± 2.88 (range 88-98) postoperatively. The mean Kujala scores increased from 58.51 ± 8.94 (range 49-76) points to 93.66 ± 2.65 (range 87-98) postoperatively. The two-tailed P value was less than 0.0001. The patients were followed until their skeletal maturation, without reporting any incidents of patella dislocation, except one.

CONCLUSION

The Roux-Goldthwait technique combined with lateral retinaculum release, and the advancement of VMO, can restore patellar tracking and can decrease the probability of another dislocation. It was an effective treatment in skeletally immature patients who had two or more episodes of patellar dislocation.

LEVEL OF EVIDENCE

IV.

Trochlear Dysplasia Does Not Affect the Outcomes of Patellofemoral Autologous Chondrocyte Implantation

PURPOSE

To evaluate the influence of trochlear dysplasia on clinical outcomes after autologous chondrocyte implantation (ACI) for the treatment of large cartilage lesions in the patellofemoral joint (PFJ) with a minimum of 2 years' follow-up.

METHODS

We performed a retrospective review of prospectively collected data of all patients submitted to cartilage repair with ACI for focal cartilage defects in the PFJ by a single surgeon. Patient factors, lesion morphology, and preoperative and postoperative patient-reported outcome measures including the Knee Injury and Osteoarthritis Score, Lysholm score, Tegner activity level, and International Knee Documentation Committee Subjective Knee Evaluation Form score were collected. Two independent observers assessed preoperative imaging to determine the presence and grade of trochlear dysplasia. Patients were stratified into 2 groups based on the presence or absence of trochlear dysplasia. Patients without trochlear dysplasia served as controls. Patients were matched 1:1 for sex, age, body mass index, lesion size, and location.

RESULTS

Forty-six patients who underwent ACI in the PFJ with a mean follow-up period of 3.7 ± 1.9 years (range, 2-9 years) were enrolled in this study (23 in the trochlear dysplasia group vs 23 in the normal trochlea group). The patients' mean age was 30.1 ± 8.8 years. Patient-reported outcome measures at final follow-up did not differ between the 2 groups (P > .05). No difference in failure rates was seen between the 2 groups (n = 1 [4.3%] vs n = 1 [4.3%], P > .999). Additionally, no difference in clinical outcomes was seen between patients with high-grade dysplasia (19 patients; Dejour types B-D) and patients without dysplasia (19 patients) (P > .05).

CONCLUSIONS

ACI in the PFJ provides favorable outcomes even in patients with trochlear dysplasia, which are comparable to those in patients with normal trochlear anatomy. Thus, trochlear dysplasia seems to not influence the clinical outcomes of ACI in the PFJ.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.

[Patellar dislocation : Causes and treatment]

The causes of patellofemoral instability (PFI) are complex. In accordance with the current literature a classification was developed which clearly weights all entities and derives diagnostic and therapeutic consequences. It considers patellar instability and patellar maltracking or the complete loss of patellar tracking and differentiates into 5 types. Type 1: patellar dislocation without maltracking or instability with a low risk of redislocation. Type 2: high risk of redislocation, no maltracking. Type 3: instability and maltracking; reasons for maltracking are a) soft tissue contracture, b) patella alta, c) pathological tibial tuberosity trochlear groove (TTTG) distance, c) valgus deformities and e) torsional deformities. Type 4: massively unstable floating patella, which is based on a high-grade trochlear dysplasia. Type 5: maltracking without instability.

Sulcus-Deepening Trochleoplasty as an Isolated or Combined Treatment Strategy for Patellar Instability and Trochlear Dysplasia: A Systematic Review

Purpose

To highlight the indications and outcomes for sulcus-deepening trochleoplasty, when used as an isolated procedure as well as in combination with other stabilization techniques for patellar instability.

Methods

We performed a systematic review focused on outcomes and complications following trochleoplasty performed either as an isolated procedure or in combination with other procedures to address patellar instability. Inclusion criteria included studies in English that reported on outcomes following primary open trochleoplasty, including Kujala scores and recurrent instability or dislocation events.

Results

Twelve papers including 702 patients who underwent sulcus-deepening trochleoplasty were included. A total of 504 patients underwent isolated sulcus-deepening trochleoplasty, whereas 198 patients underwent trochleoplasty in combination with 1 or more additional stabilization procedures. In total, 67% of patients were female compared with 33% male. The procedure was done was a primary surgical intervention 74% of the time. Postoperative Kujala scores for isolated trochleoplasty ranged from 80 to 92, whereas those for combined stabilization procedures ranged from 76 to 95. The dislocation rate among the studies ranged from 0 to 8%. There was a persistent J-sign in 0 to 12% of treated knees among all studies, and a persistent apprehension test in 0 to 29% of treated knees. Return to play ranged from 65% to 83% in studies in which this was reported as an outcome.

Conclusions

Sulcus-deepening trochleoplasty performed for recurrent patellar instability in the setting of trochlear dysplasia results in improved Kujala scores and a low redislocation rate, when performed as an isolated procedure or in combination with other stabilization procedures. Greater-level evidence is needed to better evaluate the overall efficacy of this procedure in addressing patellar instability.

Level of Evidence

Level of Evidence, IV; Systematic review of level III and IV studies.

Traumatic Patellar Dislocations in Childhood and Adolescents

Patellar instability and associated patellar dislocation can result in significant pain, disability, and associated injuries in young athletes. The patellofemoral joint is a complex articulation with stabilizing restraints, both medially and laterally, that help guide the patella into the corresponding trochlear groove as the knee cycles through an extension-to-flexion arc. In addition to soft tissue injuries, many osseous aberrancies can contribute to patellar instability in young athletes, including trochlear dysplasia, patella alta, and axial and coronal plane abnormalities. There is a role for nonoperative treatment in these young athletes; however, if recurrent or associated injuries are identified surgical intervention is warranted. Correct diagnosis of the underlying cause of the patellar instability is paramount to developing a surgical plan that will yield the most favorable outcome for these young athletes.

Editorial Commentary: Trochleoplasty: Is It Really That Fearsome and Dangerous a Technique?

Trochleoplasty in patellofemoral instability has always been controversial. Most authors recognize the fundamental role of trochlear dysplasia in the genesis of patellar dislocation, and some strongly defend correcting the abnormality, yet others find it too dangerous or unnecessary. Misunderstanding or undervaluation of trochlear dysplasia leads to inappropriate or failed patellofemoral (PF) surgery, the iatrogenic complications of which are well known. Many surgeons miss a key aspect of trochlear dysplasia: the overhang or the prominence of the trochlea relative to the anterior femoral cortex, characterized by a supra-trochlear spur. Trochleoplasty should not be performed as a secondary or revision procedure, but as a primary procedure with clear indications, and the key to improved outcomes is to ensure the right indication for each patient, which can only be determined by understanding the extent of dysplasia in both the axial and sagittal planes.

Prevailing disagreement in the treatment of complex patellar instability cases: an online expert survey of the AGA Knee-Patellofemoral Committee

PURPOSE

To evaluate the current state of knowledge and potential controversies in the treatment of patellofemoral instability among orthopaedic/trauma surgeons in the German-speaking countries.

METHODS

An online survey consisting of 32 questions and three fictitious cases was sent to members of the AGA-Society for Arthroscopy and Joint Surgery. Surgeons were defined by our senior authors as high-volume or low-volume surgeons, depending on the number of their cases. The treatment of 25% of patients with patellofemoral instability and/or the performance of 50 patellofemoral instability cases per year distinguishes high- from low-volume surgeons in this study.

RESULTS

The online questionnaire was completed by 541 experienced knee surgeons from Germany (78%), Austria (10.9%), Switzerland (10.4%) and other countries (0.7%). Most surgeons prefer MPFL reconstruction as surgical intervention in patients with recurrent patellar instability (64-81%). Sixty percent of high-volume surgeons as compared to 21.8% of low-volume surgeons have ever performed a trochleoplasty. Of the overall respondents, 25% would not perform any surgical treatment on adolescents with patellar instability and an open growth plate. Of all responding surgeons, 95% would not treat patellofemoral instability with an isolated lateral release. This corresponds to recent literature showing poor outcome of its strictly isolated application.

CONCLUSION

This study provides an overview of the current management of acute and recurrent patellofemoral instability in the German-speaking countries. Results show the surgeons' awareness for highly demanding surgical possibilities for complex patellar instability cases. However, disagreement among surgeons still prevails when it comes to selecting individual multimodal treatment options. This highlights the need for treatment guidelines and algorithms for patellofemoral instability.

LEVEL OF EVIDENCE

V.

Sulcus Deepening Trochleoplasty and Medial Patellofemoral Ligament Reconstruction for Patellofemoral Instability: A 2-Year Study

PURPOSE

To evaluate outcome data of patients undergoing DeJour sulcus-deepening trochleoplasty with medial patellofemoral ligament reconstruction (MPFLR) for high-grade trochlear dysplasia at a single institution in the United States.

METHODS

A total of 67 patients (76 knees) with severe trochlear dysplasia and recurrent patellar instability were prospectively enrolled and underwent DeJour sulcus-deepening trochleoplasty with MPFLR from 2011 to 2019. Inclusion criteria included recurrent lateral patellar instability following failure of conservative treatment with radiographic evidence of severe trochlear dysplasia (DeJour types B or D). Patients with less than 2-year follow-up were excluded. Radiographic analysis, physical examination, clinical follow-up, patient demographics, and patient-reported outcome measures were obtained for all patients at each visit.

RESULTS

Forty patients (44 knees) had complete 2-year or longer follow-up and were included. The majority of patients were female (81.8%) with a mean age of 19.2 years (standard deviation [SD] 6.7; range 13.2-47.0). Follow-up ranged from 2.0 years to 6.8 years (mean 3.6 years, SD 1.35). In total, 45.5% had failed previous surgery for patellar instability. Eight knees developed arthrofibrosis and the overall reoperation rate was 27.3%. No patients had fixation failure and no further surgery was required for instability. The mean preoperative International Knee Documentation Committee score of 50.8 improved to 79.1 (P < .001), and the mean preoperative Kujala score of 56.4 improved to 86.5 (P < .001). Patients reported high satisfaction rates (mean 9.1 of 10). When applicable, 100% of patients returned to work, whereas 84.8% returned to sport. There was no significant radiographic progression of patellofemoral arthritis at a mean of 2.4 years after surgery (SD 1.7).

CONCLUSIONS

DeJour sulcus-deepening trochleoplasty combined with MPFLR and used with tibial tubercle osteotomy and lateral release is a reliable and effective treatment for recurrent patellar instability due to severe trochlear dysplasia, even in this group with many revisions of previous procedures.

LEVEL OF EVIDENCE

IV, case series.

Increasing hospital admissions for patellar instability: a national database study from 2004 to 2017

Objectives: Epidemiology of patellar instability is not fully characterized, as some studies have produced conflicting information or been drawn from limited populations. In this study, we used the Pediatric Health Information System (PHIS) database to examine trends in admissions for patellar instability throughout the United States. We hypothesized that there would be an increasing rate of patellar instability admissions in recent years. Secondarily, we examined how demographic factors and insurance status relate to admissions for patellar instability.Methods: This study queried the Pediatric Health Information System (PHIS). Patients with ICD 9 & 10 codes 8363, 8364, 71,785, M221.0, S83.001, S83.002, S83.003, S83.004, S83.005, and S83.006, were abstracted from PHIS. We included all patients admitted with patellofemoral dislocations that were reported in the PHIS database between 1 January 2004 and 30 April 2017. The rate of patellar instability admissions was examined as well as demographic factors and insurance status.Results: An estimated total of 25,413 admissions for patellar instability were identified by the search of the PHIS database; 15,444 (60.8%) were female patients and 9,966 (39.2%) were male. The adjusted number of admissions per reporting hospital significantly increased over the years studied (r = 0.775, p < 0.001), from 14.5 admissions per reporting hospital in 2004 to 86.0 admissions per reporting hospital in 2016. Of all patellar instability admissions, 55.0% were white, 20.4% were black, 1.7% were Asian, and 22.9% were unknown race. A larger number of admissions occurred in patients with insurance status other than Medicaid in every year data were collected.Conclusions: Based on a PHIS database search, pediatric hospital admissions for patellar instability are steadily increasing. The majority of patients admitted for patellar instability are female, white, and have insurance other than Medicaid. Males admitted for patellar instability tended to be older than females admitted for the same.Level of evidence: II.

Patellar-Trochlear Morphology in Pediatric Patients From 2 to 11 Years of Age: A Descriptive Analysis Based on Computed Tomography Scanning

BACKGROUND

Despite the critical role the trochlea plays in patellofemoral (PF) pathology, the development of the trochlea is poorly understood. The purpose of this study was 2-fold: (1) Describe quantitative osseous and soft tissue anatomy of the patella and trochlea in skeletally immature cadaveric specimens utilizing known measurements used in PF instability, and (2) evaluate additional measurement techniques in the sagittal plane as they relate to PF morphologic development.

METHODS

Thirty-one skeletally immature fresh frozen cadaveric knees between the ages of 2 and 11 years old were evaluated using 0.625 mm computed tomography scans. In the axial plane, measurements included condylar height asymmetry, trochlear facet asymmetry, trochlear depth, osseous sulcus angle, cartilaginous sulcus angle, patella sulcus angle, and tibial tubercle-trochlear groove distance. In the sagittal plane, measurements included previously undescribed measurements of trochlear length and condylar height asymmetry which are based on the anterior femoral cortex.

RESULTS

Analysis of trochlear morphology using condylar height asymmetry (both axial and sagittal), trochlear facet asymmetry, and trochlear depth and length demonstrated an increase in the size of the medial and lateral trochlea as age increased. There was more variability in the change of size of the medial trochlea (height, length, and facet length) than the lateral trochlea. The osseous sulcus angle, cartilaginous sulcus angle, and patella sulcus angle decreased (became deeper) with age until after 8 years and then plateaued.

CONCLUSIONS

This cadaveric analysis demonstrated that there is an increase in the medial and lateral trochlear height as age increased by all measurements analyzed. The findings also demonstrate that the shape of the patella and trochlea change concurrently, which suggests that there may be interplay between the 2 during development. These new sagittal measurement techniques evaluating the medial, central, and lateral trochlear height and length with respect to age may help guide clinicians when investigating patellar instability in skeletally immature patients.

LEVELS OF EVIDENCE

Level IV.

Recurrent Patellofemoral Instability in the Pediatric Patient: Management and Pitfalls

PURPOSE OF REVIEW

The purpose of the review is to discuss the relevant pathoanatomy, management, complications, and technical considerations for recurrent patellofemoral instability (PFI) in the pediatric population. Special consideration is given to recent literature and management of the patient with repeat instability following surgery.

RECENT FINDINGS

Patellar stabilization surgery is in principle dependent upon restoration of normal patellofemoral anatomy and dynamic alignment. Historically, treatment options have been numerous and include extensor mechanism realignment, trochleoplasty, and more recently repair and/or reconstruction of the medial patellofemoral ligament (MPFL) as a dynamic check rein during initial knee flexion. In skeletally immature patients, preference is given to physeal-sparing soft tissue procedures. While medial patellofemoral ligament reconstruction has become a popular option, postoperative failure is a persistent issue with rates ranging from 5 to 30% for PFI surgery in general without any single procedure (e.g., distal realignment, MPFL reconstruction) demonstrating clear superiority. Failure of surgical patellar stabilization is broadly believed to occur for three main reasons: (1) technical failure of the primary stabilization method, (2) unaddressed static and dynamic pathoanatomy during the primary stabilization, and (3) intrinsic risk factors (e.g., collagen disorders, ligamentous laxity). PFI is a common orthopedic condition affecting the pediatric and adolescent population. Treatment of repeat instability following surgery in the PFI patient requires understanding and addressing underlying pathoanatomic risk factors as well as risks and reasons for failure.

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

BACKGROUND

Our 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.

METHODS

We 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.

RESULTS

Mean 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).

CONCLUSIONS

In 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 EVIDENCE

III, case control study.

Compared outcomes 16 and 25 years after lateral wedge augmentation trochleoplasty: Rate of recurrent dislocation and progression to osteoarthritis

BACKGROUND

Lateral wedge augmentation trochleoplasty (LWAT) was the earliest described trochleoplasty technique but was gradually replaced by other methods for the treatment of patello-femoral instability with trochlear dysplasia. Data on the outcomes of this procedure in adults are limited. We therefore performed a retrospective study in patients managed by LWAT to assess (1) clinical (recurrent instability and functional scores), (2) and radiological (patello-femoral osteoarthritis) outcomes.

HYPOTHESIS

LWAT is associated with a low long-term rate of recurrent patello-femoral dislocation and with no risk of progression to severe patello-femoral osteoarthritis.

MATERIAL AND METHODS

Between 1988 and 1995, LWAT was performed on 66 knees in 58 patients to treat patello-femoral instability with trochlear dysplasia. Among them, 17 knees in 13 patients were re-evaluated 16 then 25 years after surgery and were included in the study. At both time points, the following were recorded: stability, pain, the Lille patello-femoral function score, and changes in radiographic and computed tomography findings. In addition to LWAT, Insall's realignment vastus medialis advancement was performed in 4 cases, sartorius muscle transposition in 9 cases, and anterior tibial tubercle osteotomy in 10 cases.

RESULTS

No episodes of patello-femoral dislocation were recorded during the 25-year follow-up. The mean Lille patello-femoral function score (0 worst to 100 highest) was 90±15 (range, 48-99) after 16 years and 86±23 (range, 33-94) after 25 years. After 16 years, 8/17 knees had evidence of patello-femoral osteoarthritis, which was Iwano stage 1 in 7 cases and Iwano stage 2 in 1 case. Patello-femoral osteoarthritis was noted in 12 of 13 knees after 25 years but was mild (Iwano stage 1 or 2) in 8 cases. After 25 years, arthroplasty had been performed for 4 of the 17 knees, with 2 cases each of patello-femoral arthroplasty and total knee arthroplasty.

CONCLUSION

LWAT is a reliable procedure that provides sustained protection against patello-femoral dislocation and good functional scores when used to treat patello-femoral instability due to trochlear dysplasia. Our results do not support claims that LWAT may be associated with high rates of severe osteoarthritis even after more than 20 years.

LEVEL OF EVIDENCE

IV, retrospective observational study with no control group.

Isolated trochleoplasty for recurrent patellar dislocation has lower outcome and higher residual instability compared with combined MPFL and trochleoplasty: a systematic review

PURPOSE

To identify the efficacy of isolated trochleoplasty (TP) as an independent treatment for severe trochlear dysplasia compared with TP combined with medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Search of current literature using terms (trochleoplasty and medial patellofemoral ligament reconstruction) in the electronic search engines PubMed and Embase, and Medline databases was performed on February 25, 2018, and it yielded 515 abstracts for review. At the end of the search, six articles met specific inclusion criteria and were included in this review. Means were calculated for population size, age and follow-up time. The Kujala score was analyzed as the primary clinical outcome parameter in the meta-analysis. Pooled estimates were calculated for postoperative complications.

RESULTS

Six studies with a total of 192 knees (168 patients) were included in this analysis. The isolated TP group comprised of 3 articles with a total of 111 knees, and the TP combined with MPFL group comprised of 3 articles with a total of 81 knees. At the final follow-up, the preoperative Kujala score increased significantly by 21.39 (95% CI 18.94, 23.84; P < 0.00001) points in the isolated TP group and by 24.91 (95% CI 15.47, 34.36; P < 0.00001) points in the TP combined with MPFL group. The rates of subjective patellar instability including subluxation and anterior knee pain were 1.03% and8.45% respectively. Meanwhile, the rate of objective patellar redislocation was 2.06% in isolated TP group and 0% in TP combined with MFPL group. A total of 8.24% returned to the operating room for additional procedures in the isolated TP group and 7.04% in the TP combined with MPFL group.

CONCLUSION

Trochleoplasty is a useful and reliable surgical technique to improve patellofemoral instability in patients with a dysplastic trochlea. However, it as isolated treatment for patients has lower outcome and higher residual instability compared with combined MPFL and trochleoplasty.

Manipulation Under Anesthesia With Lysis of Adhesions Is Effective in Arthrofibrosis After Sulcus-Deepening Trochleoplasty: A Prospective Study

Background

Sulcus-deepening trochleoplasty has been established as an effective treatment for patellar instability due to trochlear dysplasia. However, arthrofibrosis is a known complication following trochleoplasty, which may require manipulation under anesthesia (MUA) with or without lysis of adhesions (LOA) to increase the knee range of motion (ROM), especially flexion.

Purpose

To prospectively follow patients for ROM improvements and subsequent complications after undergoing MUA with or without LOA in the setting of sulcus-deepening trochleoplasty.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 76 knees with severe trochlear dysplasia were prospectively enrolled and underwent sulcus-deepening trochleoplasty, with a mean (±SD) follow-up of 32.5 ± 19.3 months. Concomitant procedures included medial patellofemoral ligament reconstruction, lateral retinacular release, and tibial tubercle osteotomy. Physical examination including ROM and findings of recurrent patellar instability were collected for all patients. Arthrofibrosis was defined as active and passive flexion less than 90° within 3 months of surgery combined with a plateau in progress with physical therapy. Paired-samples and independent-samples t tests were used. A P value less than .05 was considered significant.

Results

A total of 62 knees met inclusion and exclusion criteria and were included in the study. Of these patients, 11 experienced arthrofibrosis as a complication and underwent MUA within 3 months of their index procedure. Of these 11 patients, 9 subsequently underwent arthroscopic LOA following MUA because acceptable ROM could not be achieved with manipulation alone. Patients with arthrofibrosis had a premanipulation mean ROM that was significantly different from those without arthrofibrosis (77.3° ±18.6° vs 133.3° ± 12.7°, respectively; P < .001). In the arthrofibrotic group, postoperative ROM increased significantly after MUA and/or LOA compared with the preoperative ROM (127.3° ± 12.5° vs 77.3° ± 18.6°, respectively; P < .001). ROM in the arthrofibrotic group after MUA/LOA was not significantly different from that in the nonarthrofibrotic group (flexion, 127.3° ± 12.5° vs 133.3° ± 12.7°, respectively; P = .156). No complications from the MUA or LOA were reported at subsequent follow-up visits.

Conclusion

When indicated in the setting of severe trochlear dysplasia, sulcus-deepening trochleoplasty is a treatment for disabling recurrent patellar instability with a known complication of arthrofibrosis. Initiation of postoperative physical therapy within 3 days of surgery may reduce the incidence of arthrofibrosis. If arthrofibrosis is encountered after a sulcus-deepening trochleoplasty, MUA without LOA is not as effective as when following other procedures of the knee, whereas MUA with LOA is an effective procedure likely to result in ROM and patient outcome scores similar to those of a nonarthrofibrotic knee after the same procedure. Both MUA and LOA appear to be safe based on the limited number of patients in this study without complication.

Trochleoplasty provides good clinical outcomes and an acceptable complication profile in both short and long-term follow-up

PURPOSE

The purpose of this study is to report on the global distribution and clinical outcomes of published articles related to trochleoplasty.

METHODS

The online databases OVID Medline, OVID EMBASE, and the Cochrane Library were searched for the literature assessing trochleoplasty performed for lateral patellofemoral instability (LPI). Study data were abstracted looking at global trends in the literature, as well as clinical and patient-reported outcomes following this technique.

RESULTS

For the assessment of global distribution, 29 studies including 998 patients met the inclusion criteria. The majority of the studies were conducted in Europe (93%) and most used an open thin flap technique (52%). For the secondary analysis of clinical outcomes, 21 studies were included with significant heterogeneity in patient selection, reporting on the degree of trochlear dysplasia, and patient-reported outcomes. All trochleoplasty techniques showed statistically significant improvement in clinical outcomes at average 50 months (range 3-228 months) post-operative, with most patients being satisfied with their procedure. Re-dislocation and complication rates were low.

CONCLUSIONS

European centers have published majority of data on trochleoplasty surgery, which has been shown to be an acceptable procedure for patients with high-grade trochlear dysplasia and LPI. Trochleoplasty has demonstrated good clinical outcomes, a low re-dislocation rate, and an acceptable complication profile in both short and long-term follow-up. This study highlights the difficulty in reporting outcomes in this group of patients due to heterogeneity in patient selection, grading of trochlear dysplasia, and the lack of disease-specific outcome measures.

LEVEL OF EVIDENCE

IV.

Tibial Tubercle Osteotomy and Medial Patellofemoral Ligament Imbrication for Patellar Instability Due to Trochlear Dysplasia

Background:

The treatment of patellar instability in the setting of trochlear dysplasia is challenging.

Purpose/Hypothesis:

The purpose of this study was to evaluate outcomes for the treatment of recurrent patellar dislocations due to trochlear dysplasia using anteromedialization tibial tubercle osteotomy combined with medial patellofemoral ligament (MPFL) imbrication. We hypothesized that the treatment of patellar instability with tibial tubercle osteotomy and MPFL imbrication would result in improved patient satisfaction and decrease patellar instability events in patients with prior instability and trochlear dysplasia.

Study Design:

Case series; Level of evidence, 4.

Methods:

We performed a retrospective analysis of patients who underwent MPFL imbrication and concomitant anteromedialization tibial tubercle osteotomy for recurrent patellofemoral instability at a single institution. The minimum follow-up was 1 year. Patient demographic information including age at the time of surgery, sex, body mass index (BMI), tibial tubercle–trochlear groove (TT-TG) distance, and grade of trochlear dysplasia was collected along with relevant operative data. Postoperatively, recurrent dislocation events as well as Knee injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Index, and Kujala scores were collected, and satisfaction was ascertained by asking patients whether they would undergo the procedure again.

Results:

A total of 37 knees from 31 patients (23 female) with a mean follow-up of 3.8 years (range, 1-8.9 years) were included. The mean patient age was 28.8 years (range, 14-45 years), the mean BMI was 24 kg/m² (range, 20-38 kg/m²), and the mean preoperative TT-TG distance was 18.9 mm (range, 8.4-32.4 mm). Two knees were classified as low-grade trochlear dysplasia (Dejour A) and 35 as high-grade trochlear dysplasia (Dejour B-D). At final follow-up, patients reported mean KOOS subscale scores of 86.5 (Pain), 79.8 (Symptoms), 93.9 (Activities of Daily Living), 74.3 (Sports/Recreation), and 61.9 (Quality of Life), as well as a mean Kujala score of 81.3. Mean patient satisfaction was 8.3 of 10. The majority of knees (86.5%; 32/37) remained stable without recurrent instability after this procedure, while 13.5% (5 knees) suffered a recurrent dislocation, with 2 requiring revision surgery. Eight knees (21.6%) underwent subsequent hardware removal.

Conclusion:

Anteromedialization tibial tubercle osteotomy with MPFL imbrication can improve recurrent patellofemoral instability and provide significant clinical benefit to patients with trochlear dysplasia.

Trochleoplasty, Medial Patellofemoral Ligament Reconstruction, and Open Lateral Lengthening for Patellar Instability in the Setting of High-Grade Trochlear Dysplasia

Trochlear dysplasia is the most commonly encountered pathoanatomy in patients who present with patellar instability. Outcomes of trochleoplasty procedures have shown low rates of recurrent instability and high patient-reported outcome scores. This article describes a "thin-flap" groove-deepening trochleoplasty combined with medial patellofemoral ligament reconstruction with a gracilis allograft and lateral retinacular lengthening to treat recurrent patellar instability due to high-grade trochlear dysplasia. This technique can obviate tibial tubercle osteotomy by normalizing the position of the trochlear groove and, subsequently, decreasing the tibial tubercle-to-trochlear groove distance.

Deepening trochleoplasty and medial patellofemoral ligament reconstruction normalize patellotrochlear congruence in severe trochlear dysplasia

AIMS

The aim of this study was to evaluate cartilaginous patellotrochlear congruence and patellofemoral alignment parameters after deepening trochleoplasty in severe trochlear dysplasia.

PATIENTS AND METHODS

The study group comprised 20 patients (two male, 18 female; mean age 24 years (16 to 39)) who underwent deepening trochleoplasty and medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent lateral patellar dislocation due to severe trochlear dysplasia (Dejour type B to D). Pre- and postoperative MRI investigations of the study group were compared with MRI data of 20 age- and gender-matched control patients (two male, 18 female; mean age 27 years (18 to 44)) regarding the patellotrochlear contact ratio, patellotrochlear contact area, posterior patellar edge-trochlear groove ratio, and patellar tilt.

RESULTS

Preoperatively, all parameters in the study group indicated significant patellar malalignment, including a reduced patellotrochlear contact ratio (mean 0.38 (0.13 to 0.59) vs mean 0.67 (0.48 to 0.88); p < 0.001), reduced contact area (mean 128 mm² (87 to 190) vs mean 183 mm² (155 to 227); p < 0.001), increased patellar lateralization (mean 0.82 (0.55 to 1.0) vs mean 0.99 (0.93 to 1.1); p < 0.001) and increased patellar tilt (mean 25.8° (8.1° to 43.0°) vs mean 9.1° (0.5° to 16.8°); p < 0.001). Postoperatively, all parameters in the study group improved significantly and reached normal values compared with the control group. The patellotrochlear contact ratio increased to a mean of 0.63 (0.38 to 0.85) (p < 0.001), the contact area increased to a mean of 187 mm² (101 to 255) (p < 0.001), the posterior patellar edge-trochlear groove ratio improved to a mean of 0.96 (0.83 to 0.91) (p < 0.001), and the patellar tilt decreased to a mean of 13.9° (8.1° to 22.1°) (p < 0.001) postoperatively.

CONCLUSION

Deepening trochleoplasty and MPFL reconstruction normalized the patellotrochlear congruence and patellofemoral alignment parameters. Modifying the dysplastic trochlea involves approximating the trochlear morphology to the shape of the patella rather than inducing a patella and trochlea mismatch. Cite this article: Bone Joint J 2019;101-B:325-330.

A combined procedure with Bereiter-type trochleoplasty leads to a stable patellofemoral joint at 5-year follow-up

PURPOSE

Trochlear dysplasia is a major risk factor predisposing to patellar instability and has been reported to occur in up to 85% of patients with recurrent patellar dislocation. Different operative techniques have been described to correct trochlear dysplasia, including the Bereiter technique, in which subchondral bone is removed and the cartilage can be compressed into a U-shaped groove. The hypothesis was that after a Bereiter-type trochleoplasty combined with medialisation of the tibial tubercle and MPFL reconstruction, patellar pain and instability decreased and anatomic reconstruction can be seen radiographically after 5-year follow-up.

METHODS

Between 2004 and 2011, a combined procedure including Bereiter-type trochleoplasty was performed on 21 consecutively included patients (22 knees) with objective patellar instability and severe trochlear dysplasia. Instability and pain were assessed preoperatively and 3, 6, 12, 24 and 60 months postoperatively with the visual analogue scale (VAS) for pain and instability, Kujala, International Knee Documentation Committee Subjective Knee Evaluation (IKDC SKE) and Short Form Health Survey (SF-36). Pre- and postoperatively, a true lateral radiograph was made to investigate the presence of the crossing sign and to measure the trochlear bump and trochlear depth, as well as a sunrise patella view to measure the sulcus angle.

RESULTS

VAS pain and instability, Kujala and IKDC SKE improved significantly 5 years after trochleoplasty (p < 0.05). SF-36 showed no significant improvement. None of the patients reported patellar dislocations postoperatively. Sport activities remained limited. Postoperative radiographs showed no crossing sign. There was a significant increase in trochlear depth (p < 0.0001) and also a significant decrease in trochlear bump and sulcus angle (both p < 0.0001).

CONCLUSIONS

A combined procedure consisting of Bereiter-type trochleoplasty, medialisation of the tibial tubercle and MPFL reconstruction in patients with objective patellar instability and severe trochlear dysplasia resulted in a clear decrease of pain and instability. Radiological assessment showed anatomical reconstruction. Nevertheless, residual symptoms remain and the possibility of future cartilage damage is uncertain.

LEVEL OF EVIDENCE

IV.

Return-to-Sport Testing After Medial Patellofemoral Ligament Reconstruction in Adolescent Athletes

Background

Return to sport (RTS) after patellar stabilization surgery involves the return of strength and dynamic knee stability, which can be assessed using isometric strength and functional performance testing.

Purpose

To investigate the results of isometric strength and functional RTS testing between the surgical and uninvolved limbs in adolescent patients who underwent medial patellofemoral ligament (MPFL) reconstruction for patellar instability.

Study Design

Case series; Level of evidence, 4.

Methods

A retrospective review of adolescent patients who underwent MPFL reconstruction identified 28 patients (20 female, 8 male) who also underwent isometric and functional RTS testing. Data were compared with the uninvolved limb. The recovery of muscle strength was defined by a limb symmetry index (LSI) ≥90%. Differences in peak torque were compared using the Wilcoxon signed-rank test. Correlations were examined between dependent and independent variables using the Spearman correlation.

Results

The mean age of the patients was 14.9 years (range, 12-16 years). Reconstruction was performed with a hamstring autograft in 17 (60.7%) patients. Concomitant tibial tubercle osteotomy was performed in 10 (35.7%) patients. Testing was performed at a mean 7.4 months (range, 5.5-11.9 months) postoperatively. The mean LSIs for quadriceps and hamstring strength were 85.3% and 95.1%, respectively. For knee extension, there was a statistically significant difference between isometric peak torque measured in the surgical and uninvolved limbs (P = .001). Only 32.0% of patients passed all 4 hop tests. Also, 63.0% of patients achieved an anterior reach asymmetry of <4 cm on the Lower Quarter Y-Balance Test (YBT-LQ). There were no statistically significant differences in isometric strength testing, hop tests, or the YBT-LQ based on graft type or concomitant procedures. There was no correlation between isometric strength and performance on the YBT-LQ or hop tests.

Conclusion

Adolescent athletes undergoing MPFL reconstruction may need prolonged rehabilitation programs beyond 8 months to allow the adequate recovery of muscle strength for safe RTS. There is a significant deficit in isometric quadriceps strength in the surgical limb after surgery. Further investigation is needed to determine safe RTS criteria after MPFL reconstruction in the pediatric and adolescent population.

Trochleoplasty techniques provide good clinical results in patients with trochlear dysplasia

PURPOSE

The aim of this systematic review is to compare the clinical outcomes of patients treated with different trochleoplasty procedures, the rate of complications and recurrence of patellar dislocation.

METHODS

A systematic review of the literature was performed, in accord with the PRISMA guidelines. PubMed, MEDLINE, CINAHL, Cochrane, EMBASE and Google Scholar databases were comprehensively searched using the keyword combinations, "Dejour trochleoplasty", "Bereiter Trochleoplasty", "Albee Trochleoplasty", "Recession Trochleoplasty", "Trochlear Dysplasia", "Instability", "Adult", "Clinical Outcome" and "Surgery".

RESULTS

Three-hundred and ninety-two knees in 371 patients were included. Bereiter U-shaped deepening trochleoplasty was the most commonly used technique for the treatment of trochlear dysplasia in the included studies with the lowest rate of recurrence and post-operative ROM deficiency. On the other hand, Dejour V-shaped deepening trochleoplasty showed the highest mean post-operative value of Kujala score with 79.3 (SD 8.4) points. Statistical differences were found in terms of redislocation rate between Goutallier procedure and Bereiter trochleoplasty (p < 0.05) and in terms of post-operative osteoarthritis between Bereiter and Dejour procedures (p < 0.05).

CONCLUSION

Bereiter trochleoplasty seems to be the most efficiency procedure in terms of post-operative patellar redislocation, post-operative osteoarthritis and ROM, but the highest mean post-operative Kujala score is obtained by Dejour procedure. Therefore, none of the surgical techniques analysed highlighted a real superiority. Randomised clinical trials are needed to establish whether of available surgical technique is the best to treat patient with trochlear dysplasia. The clinical relevance of this paper is that the three most popular trochleoplasty techniques are associated with significantly improved stability and function, showing a relatively low rate of osteoarthritis and pain, and a moderate rate of complications.

LEVEL OF EVIDENCE

Systematic review, Level IV.

Lateral Patellar Instability in the Skeletally Mature Patient: Evaluation and Surgical Management

Lateral patellar instability is a common disease process that affects all types of patients. Depending on the patient's anatomy and the results of preoperative imaging, surgical management options include medial patellofemoral ligament reconstruction, tibial tubercle osteotomy, and sulcus-deepening trochleoplasty. Medial patellofemoral ligament reconstruction or repair is useful for almost all patients, whereas tibial tubercle osteotomy is helpful to correct a lateralized tibial tubercle and the associated elevated lateral pull of the extensor mechanism. For a select subset of patients with severe trochlear dysplasia, a sulcus-deepening trochleoplasty can be a useful option to prevent future patellar instability. Many technical considerations exist for each procedure, and in most situations, no consensus exists to direct surgeons on the superior technique.

Trochleoplasty: Indications and Technique

PURPOSE OF REVIEW

Trochlear dysplasia is a well-described risk factor for patellar instability. Trochleoplasty has emerged as a procedure within the surgical armamentarium for patellar instability, yet its role is unclear. A variety of trochleoplasty procedures have emerged. The purpose of this review is to clarify indications for trochleoplasty, outline the technical steps involved in performing common trochleoplasties and report the published outcomes and potential complications of these procedures.

RECENT FINDINGS

Patellar instability with severe trochlear dysplasia is the main indication for trochleoplasty. Three types of trochleoplasty have emerged: (1) lateral facet elevation; (2) sulcus deepening; and (3) recession wedge. Deepening and recession wedge trochleoplasties are the most commonly performed. Trochleoplasty is a surgical option for addressing patellar instability in patients with severe trochlear dysplasia. Deepening and recession wedge trochleoplasties that address Dejour B and D dysplastic trochleas are the most studied, with both short- and midterm outcomes reported. Long-term outcomes are lacking and comparative studies are needed.

Patellar Instability: When is Trochleoplasty Necessary?

Trochleoplasty is a very effective procedure for correcting trochlear dysplasia and addressing instability of the patella. With an increasing knowledge about the anatomy and biomechanics of the anterior distal femur, a wider array of surgical techniques may be applied to address specific conditions. Patients must be carefully selected to undergo trochleoplasty by use of a thorough history and physical examination as well as basic and advanced imaging. The presence of a "J sign" on physical examination, a history of recurrent instability, patella alta, trochlear dysplasia, and elevated tibial tubercle to trochlear groove are signs and symptoms for which the patient should be evaluated. We attempt to elucidate when trochleoplasty is indicated by means of addressing all aspects of evaluation.

Return to Play after Patellar Stabilization

PURPOSE OF REVIEW

The purpose of this review is to evaluate the existing literature regarding return to play (RTP) and return to prior performance (RPP) following patellar stabilization surgery. It will also discuss suggested guidelines regarding RTP, and finally, to encourage future patellofemoral instability research to report and publish results of RTP rates using standardized RTP guidelines.

RECENT FINDINGS

There is a lack of validation and universal adoption of standardized RTP guidelines. This has led to a dearth of high-quality studies on RTP and RPP after patellar stabilization. The best available studies to date would suggest high RTP rates (84%-100%), average RPP rates (33%-77%), and a highly variable timeframe for return (3-12 months). Patellofemoral instability can be a persistent and challenging problem, particularly in the young and active population for which it most often occurs. Much of the previous studies on patellofemoral instability evaluated success and failure as prevention of recurrent dislocation. However, prevention of recurrence alone may not be enough for many patients. The best available data on RTP and RPP following patellofemoral instability is based on lower quality of evidence studies, expert opinion, and published societal guidelines. Future research on this topic should include clinical validation of the International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine (ISAKOS) RTP guidelines and reporting of outcomes based on these guidelines in patellofemoral instability publications.