Does different duration of non-operative immobilization have an effect on the redislocation rate of primary patellar dislocation? A retrospective multicenter cohort study

Patellofemoral instability part 1 (When to operate and soft tissue procedures): State of the art

Patellofemoral instability is usually initially treated non-operatively. Surgery is considered in patients with recurrent patellar dislocation and after a first-time patellar dislocation in the presence of either an associated osteochondral fracture or high risk of recurrence. Stratifying the risk of recurrence includes evaluating risk factors such as age, trochlear dysplasia, contralateral dislocation, and patellar height. Surgery with soft tissue procedures includes restoring the medial patellar restraints and balancing the lateral side of the joint. Reconstruction of the medial patellofemoral ligament is the most frequent way of addressing the medial soft tissues in patients with patellofemoral instability. Meanwhile, lateral tightness can be achieved by lateral retinaculum lengthening or release. Approaching patellofemoral instability in a patient-specific approach, combined with a shared decision-making process with the patient/family, will guide surgeons to the deliver optimal care for the patellar instability patient.

Consensus-Based Guidelines for Management of First-Time Patellar Dislocation in Adolescents

BACKGROUND

The management of first-time patellar dislocation remains variable, with limited evidence to support or compare different operative and nonoperative modalities. The primary aim was to establish consensus-based guidelines for different components of nonoperative treatment following a first-time patellar dislocation. The secondary aim was to develop guidelines related to management after failed nonoperative treatment. The tertiary aim was to establish consensus-based guidelines for the management of first-time patellar dislocation with a concomitant osteochondral fracture.

METHODS

A 29-question, multiple-choice, case-based survey was developed by 20 members of the Patellofemoral Research Interest Group of the Pediatric Research in Sports Medicine Society. The survey consisted of questions related to demographic information, management of first-time patellar dislocation without an osteochondral fracture, and management of first-time patellar dislocation with a 2 cm osteochondral fracture. The survey underwent 2 rounds of iterations by Patellofemoral Research Interest Group members and the final survey was administered to Pediatric Research in Sports Medicine members, using REDCap. Consensus-based guidelines were generated when more than 66% of respondents chose the same answer.

RESULTS

Seventy-nine of 157 (50%) eligible members responded. Sixty-one were orthopaedic surgeons and 18 were primary sports medicine physicians. Eleven consensus-based guidelines were generated based on survey responses. Those that met the criteria for consensus included initial knee radiographs (99% consensus), nonoperative treatment for first-time patellar dislocation without an osteochondral fracture (99%), physical therapy starting within the first month postinjury (99%), with return to sport after 2 to 4 months (68%) with a brace (75%) and further follow-up as needed (75%). Surgical treatment was recommended if there were patellar subluxation episodes after 6 months of nonoperative treatment (84%). Patellar stabilization should be considered for a first-time dislocation with an osteochondral fracture (81.5%).

CONCLUSION

Consensus-based guidelines offer recommendations for the management of first-time patellar dislocation with or without an osteochondral fracture. Several changing trends and areas of disagreement were noted in clinical practice.

CLINICAL RELEVANCE

In the absence of high-level evidence, consensus-based guidelines may aid in clinical decision-making when treating patients following a first-time patellar dislocation. These guidelines highlight the evolving trends in clinical practice for the management of first-time patellar dislocation. Areas not reaching consensus serve as topics for future research.

Prevalence and Site of Concomitant Osteochondral Injuries in Patients With Acute Lateral Patellar Dislocation: A Systematic Review and Meta-analysis

Background

Osteochondral injuries (OCIs) are common in patients with acute lateral patellar dislocation, which can produce both short- and long-;term adverse effects. However, the pattern of these injuries warrants further analysis, especially in relation to patient age.

Purpose

To determine the overall prevalence of concomitant OCIs as well as the prevalence differences based on location and age after acute lateral patellar dislocations.

Study Design

Systematic review; Level of evidence, 4.

Methods

A comprehensive search of PubMed, Embase, Web of Science, and Cochrane Library was completed from inception to July 20, 2022. All articles reporting the prevalence of OCI were included. The sample characteristics such as age, study design, magnetic resonance imaging diagnostic data, and the number of patients with OCI were extracted. The Methodological Index for Non-Randomized Studies (MINORS) was used for quality assessment. The overall and per-;site injury rates were calculated, and the prevalence was stratified by age-;group (≤16 and >16 years) and compared.

Results

The systematic review included 39 studies involving 3354 patients. MINORS scores were 11.94 ± 1.98 and 16 ± 3.46 in the noncomparative and comparative studies, respectively. The overall prevalence of bone bruises and OCI was 89.6% (95% CI, 77.4%-97.7%) and 48.8% (95% CI, 39.0%-58.7%), respectively. In both overall and >16-year-old patients, the lateral femoral condyle (LFC) was the most common site of bone bruise (90.5% [95% CI, 84.0%-95.6%] and 91.5% [95% CI, 84.3%-96.9%], respectively); however, the medial patellar bruise was more common in patients ≤16 years (89.2% [95% CI, 82.9%-94.4%]). Among the pooled sites of OCI, the medial patella accounted for the largest proportion (36.9% [95% CI, 28.0%-46.3%]). OCIs were more common in patients >16 years (52.6% [95% CI, 39.4%-65.6%]) than in patients ≤16 years (46.6% [95% CI, 33.2%-60.3%]).

Conclusion

Bone bruises on the LFC were most prevalent overall and in patients >16 years, whereas bone bruises on the medial patella were more prevalent in patients ≤16 years. OCIs were frequently seen in patients >16 years, with the most common site being the medial patella.

The accuracy of multiple regression models for predicting the individual risk of recurrent lateral patellar dislocation

BACKGROUND

Recurrent lateral patellar dislocation (RLPD) poses a significant threat to patients' quality of life due to knee pain, patellofemoral cartilage damage, and potential traumatic arthritis. Predictive scoring systems have been developed to assess the risk of RLPD; however, their relative accuracy remains uncertain.

PURPOSE

To investigate the accuracy of the multiple regression models to predict the individual risk of recurrent LPD.

METHODS

The Patellar Instability probability calculator (PIP), Recurrent Instability of the Patella Score (RIP), and Patellar Instability Severity Score (PIS) scoring rules were measured in 171 patients with a history of patellar dislocation and 171 healthy individuals. Three prediction models were calculated based on the data to predict the risk of recurrent lateral patellar dislocation. The inter-observer and intra-observer reliability of each measurement parameter was evaluated. The predictive capacity of the three-prediction model was investigated using the receiver operating characteristic curve.

RESULTS

In the case group of 171 patients, PIS accurately predicted recurrent lateral Patella dislocation in 143 patients. RIP was 96, and PIP was 83. The positive predictive values were 92.9%, 64%, and 68% respectively. In the control group of 171 patients, the PIS was validated in 160 patients who would not experience dislocations. RIP was 117, and PIP was 50. The negative predictive values were 85.1%, 60.9%, and 36.2%, respectively. The area under the curve score for the PIS was 0.866, and the RIP was 0.673. the PIP was 0.678.

CONCLUSION

RIP and PIP did not work to predict LPD. PIS can accurately predict recurrent lateral patellar dislocation. It can aid doctors in making treatment decisions.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Recurrence and return to duty following patellar instability events in military personnel

INTRODUCTION

Military service members experience patellar dislocations at a rate 10 times that of civilians. The purpose of this study was to determine the return to duty rate of active duty military personnel following first-time or recurrent patellar dislocation. Secondary goals were to identify patient variables and radiographic parameters associated with recurrent instability and requiring medical separation from military service.

METHODS

The Military Health System Data Repository was used to identify all active-duty military personnel who sustained a patellar dislocation between 2013 and 2018. Medical records were searched for patient variables including demographics, clinical findings, radiographic findings, treatment, adverse outcomes and military disposition. Patient variables associated with recurrent instability and undergoing medical separation were determined using univariate analysis and multivariate logistic regression. A total of 207 patients met inclusion and exclusion criteria.

RESULTS

Following patellar instability event, 30% of the cohort underwent surgical treatment. Fourteen per cent (29 of 207) underwent medical separation from military service. Regardless of treatment, 9% (18 of 207) experienced recurrent dislocation and 3% (6 of 207) experienced recurrent instability without dislocation. On multivariate analysis, none of the studied patient variables were associated with recurrent instability or medical separation.

CONCLUSIONS

Among military personnel, return to duty rates are similar to return to sport rates in civilians. This study demonstrates no difference in risk of recurrent instability or medical separation based on anatomical factors, which is useful during shared decision-making regarding treatment options and goals.

MRI as the optimal imaging modality for assessment and management of osteochondral fractures and loose bodies following traumatic patellar dislocation: a systematic review

PURPOSE

To assess the imaging modalities used for diagnosis, as well as the management decisions of patients with osteochondral fractures (OCF) and loose bodies following traumatic patellar dislocation.

METHODS

According to the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA), MEDLINE, EMBASE, Web of Science, and PubMed were searched for results from January 1, 2000, to May 18, 2021, in two subsequent searches for English language studies that presented data on traumatic patellar dislocation. Quality of selected papers was assessed using the Methodological Index for Non-Randomised Studies (MINORS) and the Risk of Bias (RoB) 2.0 protocol. Results were qualitatively synthesised, and descriptive statistics were calculated.

RESULTS

Forty studies totalling 3074 patients (1407 females) were included for the analysis. The mean age was 18.9 years (range 0-69). The population included 2446 first-time dislocations. The imaging modalities used were: 71.1% MRI, 52.6% plain radiography, 12.1% CT, and 0.68% ultrasound. In the 25 studies that reported the number of OCF, a total of 38.3% of patients were found to have OCF. 43.3% of patients with a first-time dislocation, and 34.7% of patients with previous dislocations, had at least one OCF. In the included paediatric studies (maximum age ≤ 18), the presence of OCF was detected by plain radiography in 10.1% of patients, MRI in 76.6% of patients, and CT in 89.5% of patients. For management of an OCF, the surgical options include fixation for larger pieces, excision for smaller pieces, and conservative management on a case-by-case basis.

CONCLUSIONS

Based on the current available evidence, assessment and management of patellar dislocations and subsequent OCFs vary, with radiography and MRI as the main imaging modalities on presentation and particular benefit for MRI in the paediatric population. Findings from this study suggest the highest rate of OCF detection with MRI, and thus, surgeons should consider routinely ordering an MRI in patients with first-time patellar dislocation. Regarding management of OCFs, the main indication for fixation was large fragments, while smaller and poor-quality fragments are excised. Few studies choose conservative management of OCFs due to later requirements for surgical management. Future work should focus on large, high-quality studies, and implementation of randomised control trials to form guidelines for imaging patellar dislocations and management of OCFs.

LEVEL OF EVIDENCE

Level IV.

Lateral Patellar Dislocation: A Critical Review and Update of Evidence-Based Rehabilitation Practice Guidelines and Expected Outcomes

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Nonoperative treatment of a lateral patellar dislocation produces favorable functional results, but as high as 35% of individuals experience recurrent dislocations.

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Medial patellofemoral ligament reconstruction is an effective treatment to prevent recurrent dislocations and yield excellent outcomes with a high rate of return to sport.

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Both nonoperative and postoperative rehabilitation should center on resolving pain and edema, restoring motion, and incorporating isolated and multijoint progressive strengthening exercises targeting the hip and knee.

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Prior to return to sports, both functional and isolated knee strength measurements should be used to determine leg symmetry strength and to utilize patient-reported outcome measures to assess the patient's perceived physical abilities and patellofemoral joint stability.

Patellofemoral Dislocation Recurrence After a First Episode: A Case-Control Study

Background:

Lateral patellar dislocation can become a recurrent problem after the first episode. Identifying those patients who are at increased risk of redislocation is important for the treatment decision-making process.

Purpose:

To identify clinical and radiologic risk factors for recurrence of patellar dislocation after a first episode.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

The study included patients with lateral patellar dislocation and a 1-year minimum follow-up who were seen between 2011 and 2018. Patients aged 10 to 65 years were included. Patient characteristics, physical examination (patellar apprehension, J sign), and radiographs were reviewed. The Caton-Deschamps and Insall-Salvati ratios were used to evaluate patella alta. High-grade trochlear dysplasia was defined as Dejour types B, C, and D.

Results:

A total of 130 patients (139 knees) with primary lateral patellar dislocation were included. Recurrent dislocation was seen in 83 knees (59.71%). Stepwise logistic regression analysis demonstrated that Caton-Deschamps ratio ≥1.15 (OR, 2.39; 95% CI, 1.09-5.22; P = .029), age <21 years (OR, 2.53; 95% CI, 1.11-5.77; P = .027), and high-grade trochlear dysplasia (OR, 4.17; 95% CI, 1.90-9.17; P < .001) were significantly associated with patellar redislocation. Based on the presence of these factors, the probability of dislocation after a first lateral patellar dislocation was 31.2% with no factors present, 36.6% with any 1 factor present, 71.7% with any 2 factors present, and 86.2% if all 3 conditions were present.

Conclusion:

The results of this study indicated that patella alta, high-grade trochlear dysplasia, and age <21 years were independent risk factors for patellar redislocation after a first episode, with an additive effect when they were present together. This may help to guide the type of treatment for these patients.

Midterm Results after Implant-Free Patellar Fixation Technique for Medial Patellofemoral Ligament Reconstruction

Problems and complications concerning the patellar fixation in medial patellofemoral ligament reconstruction (MPFLR) have been reported. The purpose of this retrospective study was to systematically analyze the surgical technique for MPFLR with a V: -shaped patellar bonetunnel for implant-free fixation of an autologous gracilis tendon, allowing early functional rehabilitation, regarding restoration of the patellofemoral stability, patient satisfaction, return to sports, and technique-specific complications. In 2010, 128 cases of consecutive isolated MPFLR were performed. All these cases were included. After a minimum follow-up of 3 years, 104 cases were retrospectively analyzed (follow-up: 81.3%) with regard to redislocation, subjective functional outcome (Tegner's score and sports level compared with preoperative level), patient satisfaction, revision surgery, and technique-specific complications. After a follow-up of 45.7 ± 3.2 months, 101 of 104 cases (97.1%) showed no redislocation. Mean Tegner's score was 5.1 ± 1.8 (range, 2-9). A total of 61.5% patients reported about a higher sports level compared with their preoperative level. The patient satisfaction was high with 94.2%. In two cases (1.9%), technique-specific problems occurred as the bone bridge of the V: -shaped tunnel was insufficient due to a malpositioning of the aiming device. No further technique-specific problems occurred and no revision surgery was necessary during the observational period. The presented surgical technique is safe and it reliably restores the patellofemoral stability, with a low rate of redislocations, an excellent subjective functional outcome, and a high-patient-reported satisfaction. No major technique-specific complications occurred.

Factors Associated With an Increased Risk of Recurrence After a First-Time Patellar Dislocation: A Systematic Review and Meta-analysis

BACKGROUND

Recurrent dislocations after a first-time lateral patellar dislocation may occur in more than 50% of patients and can cause long-term disability. Many factors have been suggested to influence the risk of recurrence.

PURPOSE

To systematically review and quantitatively synthesize the literature for factors associated with an increased risk of recurrence after a first-time patellar dislocation.

STUDY DESIGN

Systematic review and meta-analysis of observational studies.

METHODS

A total of 4 electronic databases were searched to identify relevant studies published before February 7, 2019. A quality assessment was performed with the National Heart, Lung, and Bone Institute quality assessment score. Factors assessed for their effect on the recurrence rate were documented, and the rates of recurrence were compared. Pooled dichotomous data were analyzed using random-effects meta-analysis with odds ratios (ORs).

RESULTS

A total of 17 studies met the criteria for inclusion. The overall rate of recurrent dislocations after a first-time lateral patellar dislocation was 33.6%. An increased risk of recurrence was reported in patients with a younger age (OR, 2.61; P < .00001), open physes (OR, 2.72; P < .00001), trochlear dysplasia (OR, 4.15; P = .009), an elevated tibial tuberosity-trochlear groove (TT-TG) distance (OR, 2.87; P < .00001), and patella alta (OR, 2.38; P = .004). Sex, patterns of medial patellofemoral ligament injury, and history of contralateral dislocations were not found to be associated with an increased recurrence rate (P≥ .05). In studies that reported on the presence of multiple risk factors, recurrence rates were 7.7% to 13.8% when no risk factors were present but increased to 29.6% to 60.2% when 2 risk factors were present and to 70.4% to 78.5% when 3 risk factors were present.

CONCLUSION

Younger age, open physes, trochlear dysplasia, elevated TT-TG distance, and patella alta were key risk factors for the recurrence of lateral patellar dislocations. Despite being not infrequently cited as risk factors, patient sex and a history of contralateral dislocations were not found to be significant risk factors. The presence of multiple risk factors increased the risk, and the development of predictive instability scores in large patient cohorts using all established risk factors should be a focus of future studies.

Plaster, splint, brace, tape or functional mobilization after first-time patellar dislocation: what's the evidence?

With an incidence of 5.8 per 100,000 per year, patellar dislocations are commonly seen in the emergency department. Surprisingly, there are only a few studies available that focus on the results of the different non-surgical treatment options after first-time patellar dislocation. The aim of this review is to provide an overview of the most recent and relevant studies on the rationales and results of the non-surgical treatment for first-time patellar dislocation.

Patellar instability mainly affects young and active patients, with a peak incidence of 29 per 100 000 per year in adolescents. The medial patellofemoral ligament, a main passive restraint for lateral translation of the patella, is torn in lateral patellofemoral dislocations. Treatment of first-time patellar dislocation can be either conservative or surgical.

There are two options in conservative management of first-time patellar dislocation: immobilization using a cylinder cast or removable splint, or, second, functional mobilization after applying a brace or patellar tape.

The current available literature of conservative treatment after a first-time patellar dislocation is little and of low quality of evidence. Conclusions should be drawn with care, new research focussing on non-surgical treatment is therefore strongly needed.

Cite this article: EFORT Open Rev 2019;4:110-114. DOI: 10.1302/2058-5241.4.180016