First-time patellar dislocation: surgery or conservative treatment?

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Primary Patellar Instability and Need for Recurrent Surgical Stabilization

BACKGROUND

Vitamin D has been proven experimentally to affect musculoskeletal health. The purpose of this study was to identify the relationship between vitamin D deficiency and patellar instability.

HYPOTHESIS

Vitamin D deficiency is associated with an increased risk of experiencing primary patellar instability and recurrent patellar dislocation after primary surgical stabilization.

STUDY DESIGN

Retrospective comparative study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A 1:1 matched retrospective study of 328,011 patients diagnosed with vitamin D deficiency was performed using the PearlDiver database. Incidence of primary patellar instability was calculated according to sex and age. Rates of primary patellar instability and surgical stabilization for recurrent dislocation were calculated with sex- and age-specific stratifications. Multivariable logistic regression was used to compare the rates of primary injury and recurrent stabilization while controlling for demographics and medical comorbidities.

RESULTS

A total of 656,022 patients were analyzed. The overall 1-year incidence rate of patellar instability in patients with vitamin D deficiency was 82.6 per 100,000 person-years (95% CI, 73.2-92.9), compared with 48.5 (95% CI, 41.4-56.5) in the matched control. Women were significantly more likely to experience primary patellar instability within 1 (adjusted odds ratio [aOR] = 1.45; 95% CI, 1.12-1.88) and 2 years (aOR, 1.31; 95% CI, 1.07-1.59) of hypovitaminosis D diagnosis. Patients aged 10 to 25 years with hypovitaminosis D were at greater risk of requiring recurrent patellar stabilization for both men (aOR, 2.48; 95% CI, 1.06-5.80) and women (aOR, 1.77; 95% CI, 1.04-3.02).

CONCLUSION

Patients diagnosed with vitamin D deficiency experienced higher rates of primary patellar instability and have greater risk of requiring recurrent surgical stabilization for subsequent dislocations.

CLINICAL RELEVANCE

These results suggest that monitoring and proactively treating vitamin D deficiency in the physically active patient may lower the risk of suffering primary patellar instability or recurrence after surgical stabilization.

Spontaneous tendon or ligament ruptures in patients undergoing dialysis: First pediatric case report and literature review

Spontaneous tendon or ligament ruptures are quite rare and mostly associated with chronic systemic diseases such as diabetes mellitus, systemic lupus erythematosus, rheumatoid arthritis, and chronic kidney disease (CKD). In this study, we present the first documented case of a spontaneous rupture of the medial patellofemoral ligament (MPFL) in a pediatric patient. The patient was undergoing long-term peritoneal dialysis (PD) and had a history of severe secondary hyperparathyroidism. Additionally, we discussed spontaneous tendon and ligament ruptures associated with CKD or dialysis through a comprehensive literature review. This case report highlights the importance of recognizing that spontaneous tendon or ligament injuries are not exclusive to adults; children with CKD can also be affected. Several factors including poor parathyroid hormone (PTH) and metabolic acidosis control, prolonged CKD duration and presence of malnutrition play role in the pathogenesis. Early diagnosis is crucial as it allows for timely surgical intervention and leads to a favorable functional recovery.

Complication Rates After Medial Patellofemoral Ligament Reconstruction Range From 0% to 32% With 0% to 11% Recurrent Instability: A Systematic Review

PURPOSE

To review the incidence of complications following primary medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar instability.

METHODS

A literature search was conducted by querying PubMed and Scopus databases from database inception through August 2022 according to the 2020 Preferred Reporting Items for Systematic Review and Meta-analysis guidelines using the terms "Medial Patellofemoral Ligament," "MPFL," "reconstruction," "patellar," and "instability." Inclusion criteria included studies reporting complications following primary MPFL reconstruction for recurrent patellar instability. Exclusion criteria consisted of studies reporting on patients undergoing concurrent osteotomy procedures, revision reconstruction, and biomechanical or anatomic studies. The incidence of specific complications was aggregated from the included studies.

RESULTS

Twenty-eight studies, consisting of 1,478 patients (n = 1521 knees), with a mean age of 23.3 years (mean range, 19-34.3 years) were identified. The overall incidence of complications ranged from 0% to 32.3% of knees. Failure ranged from 0% to 10.7% of knees, whereas patellar fractures occurred in 0% to 8.3% of knees, primarily in patients treated with full-length transverse tunnel or 2-tunnel techniques. All patellar fractures occurred in patients with patellar tunnels ranging from 4.5 to 6.0 mm in diameter. The incidence of postoperative knee stiffness/range of motion deficit ranged from 0% to 20%. Persistent anterior knee pain, ranged from 0% to 32.3%.

CONCLUSIONS

Complications following primary MPFL reconstruction ranged from 0% to 32.3% of knees, primarily consisting of residual anterior knee pain. Failure ranged from 0% to 10.7% of knees, whereas patellar fractures were reported in 0% to 8.3% of knees. Fractures primarily occurred with a full-length transverse tunnel or 2-tunnel techniques, whereas all fractures occurred with patellar tunnels ranging from 4.5 mm to 6.0 mm in diameter.

LEVEL OF EVIDENCE

IV; Systematic Review of Level I-IV studies.

Surgical versus non-surgical interventions for treating patellar dislocation

BACKGROUND

Patellar (knee cap) dislocation occurs when the patella disengages completely from the trochlear (femoral) groove. It affects up to 42/100,000 people, and is most prevalent in those aged 20 to 30 years old. It is uncertain whether surgical or non-surgical treatment is the best approach. This is important as recurrent dislocation occurs in up to 40% of people who experience a first time (primary) dislocation. This can reduce quality of life and as a result people have to modify their lifestyle. This review is needed to determine whether surgical or non-surgical treatment should be offered to people after patellar dislocation.

OBJECTIVES

To assess the effects (benefits and harms) of surgical versus non-surgical interventions for treating people with primary or recurrent patellar dislocation.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group's Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, AMED, CINAHL, Physiotherapy Evidence Database and trial registries in December 2021. We contacted corresponding authors to identify additional studies.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled clinical trials evaluating surgical versus non-surgical interventions for treating primary or recurrent lateral patellar dislocation in adults or children.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were recurrent patellar dislocation, and patient-rated knee and physical function scores. Our secondary outcomes were health-related quality of life, return to former activities, knee pain during activity or at rest, adverse events, patient-reported satisfaction, patient-reported knee instability symptoms and subsequent requirement for knee surgery. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We included 10 studies (eight randomised controlled trials (RCTs) and two quasi-RCTs) of 519 participants with patellar dislocation. The mean ages in the individual studies ranged from 13.0 to 27.2 years. Four studies included children, mainly adolescents, as well as adults; two only recruited children. Study follow-up ranged from one to 14 years. We are unsure of the evidence for all outcomes in this review because we judged the certainty of the evidence to be very low. We downgraded each outcome by three levels. Reasons included imprecision (when fewer than 100 events were reported or the confidence interval (CI) indicated appreciable benefits as well as harms), risk of bias (when studies were at high risk of performance, detection and attrition bias), and inconsistency (in the event that pooled analysis included high levels of statistical heterogeneity). We are uncertain whether surgery lowers the risk of recurrent dislocation following primary patellar dislocation compared with non-surgical management at two to nine year follow-up. Based on an illustrative risk of recurrent dislocation in 348 people per 1000 in the non-surgical group, we found that 157 fewer people per 1000 (95% CI 209 fewer to 87 fewer) had recurrent dislocation between two and nine years after surgery (8 studies, 438 participants). We are uncertain whether surgery improves patient-rated knee and function scores. Studies measured this outcome using different scales (the Tegner activity scale, Knee Injury and Osteoarthritis Outcome Score, Lysholm, Kujala Patellofemoral Disorders score and Hughston visual analogue scale). The most frequently reported score was the Kujala Patellofemoral Disorders score. This indicated people in the surgical group had a mean score of 5.73 points higher at two to nine year follow-up (95% CI 2.91 lower to 14.37 higher; 7 studies, 401 participants). On this 100-point scale, higher scores indicate better function, and a change score of 10 points is considered to be clinically meaningful; therefore, this CI includes a possible meaningful improvement. We are uncertain whether surgery increases the risk of adverse events. Based on an assumed risk of overall incidence of complications during the first two years in 277 people out of 1000 in the non-surgical group, 335 more people per 1000 (95% CI 75 fewer to 723 more) had an adverse event in the surgery group (2 studies, 144 participants). Three studies (176 participants) assessed participant satisfaction at two to nine year follow-up, reporting little difference between groups. Based on an assumed risk of 763 per 1000 non-surgical participants reporting excellent or good outcomes, seven more participants per 1000 (95% CI 199 fewer to 237 more) reported excellent or good satisfaction. Four studies (256 participants) assessed recurrent patellar subluxation at two to nine year follow-up. Based on an assumed risk of patellar subluxation in 292 out of 1000 in the non-surgical group, 73 fewer people per 1000 (95% CI 146 fewer to 35 more) had patellar subluxation as a result of surgery. Slightly more people had subsequent surgery in the non-surgical group. Pooled two to nine year follow-up data from three trials (195 participants) indicated that, based on an assumed risk of subsequent surgery in 215 people per 1000 in the non-surgical group, 118 fewer people per 1000 (95% CI 200 fewer to 372 more) had subsequent surgery after primary surgery.

AUTHORS' CONCLUSIONS

We are uncertain whether surgery improves outcome compared to non-surgical management as the certainty of the evidence was very low. No sufficiently powered trial has examined people with recurrent patellar dislocation. Adequately powered, multicentre, randomised trials are needed. To inform the design and conduct of these trials, expert consensus should be achieved on the minimal description of both surgical and non-surgical interventions, and the pathological variations that may be relevant to both choice of these interventions.

Management of the first episode of traumatic patellar dislocation: an international survey

PURPOSE

This international survey aimed to evaluate the potential controversies regarding the management of first patellar dislocation amongst experienced knee surgeries in the treatment of the first episode of patellar dislocation without osteochondral fragments.

METHODS

An online survey was conducted from February 2021 to December 2021 to assess the global trend in the diagnosis and management of first-time patellar dislocation without osteochondral fragments. The online survey was accessible on the homepage of the website of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA). The questionnaire consisted of multiple-choice questions and was divided into three sections. The first section consisted of eight questions regarding demographic information, professional activity, and responder experience. The second section consisted of 13 questions regarding the approach to a first patellar dislocation (clinical examination, imaging, and rehabilitation). The third section contained 2 questions concerning the relevance of patient characteristics to the therapeutic algorithm (age, sports, and pathoanatomical predisposing risk factors).

RESULTS

A total of 438 orthopaedic surgeons worldwide completed the questionnaire. At the first approach to diagnose a first-time patellar dislocation, 251 (57%) of the surgeons requested plain radiographs, and 158 (36%) requested magnetic resonance imaging (MRI). In conservatively treated patients, 368 (84%) of the respondents recommended the use of a knee brace. Amongst them, 14 (3%) advocated its use for one week, 75 (17%) for two weeks, 123 (28%) for three weeks, 105 (24%) for four weeks, and 97 (22%) for six weeks. In conservatively treated patients, 215 (49%) of the surgeons recommended load to tolerance, 148 (34%) recommended 30% to 60% of the bodyweight, and 75 (17%) advised against weight-bearing. More than half of the surgeons considered a patient aged less than 35 years practising contact sports to be a candidate for the medial patello-femoral ligament (MPFL) procedure. In addition, a tibial tuberosity to trochlear groove distance (TT-TG) distance of 15 to > 20 mm (for > 75% of the surgeons) and a trochlea types C and D (for > 70% of the surgeons) were considered possible indications for direct surgical management.

CONCLUSION

At the first approach to diagnose a first-time patellar dislocation, plain radiographs and MRI should be performed. In conservatively treated patients, most of the surgeons recommend weight-bearing to tolerance and a knee brace during the first four weeks, with range of motion of full extension to 30° during the first 15 days and up to 60° for an additional 15 days. Surgical management should be performed in patients in the second and third decades of life practising contact sports and in those patients who present types C and D trochlea dysplasia and patella alta.

LEVEL OF EVIDENCE

IV.

Outcomes following the operative treatment of intra-articular fracture combined with medial patellofemoral ligament reconstruction after patellar dislocation

Purpose

We examine the outcomes following operative treatment of intra-articular fracture combined with medial patellofemoral ligament (MPFL) reconstruction after patella dislocation.

Methods

Patients were retrospectively identified from medical records using diagnostic and surgical procedure codes. Radiological anatomical parameters and bony abnormalities of injured knees were assessed from magnetic resonance images (MRI). Inclusion criteria were traumatic patellar dislocation with chondral or osteochondral fracture and MPFL rupture, operative treatment of a chondral or osteochondral fracture combined with MPFL reconstruction, and minimum follow-up of 2 years. Outcomes were measured using the Kujala score, Tegner activity scale, and the Knee injury and Osteoarthritis Outcome Score Quality-of-Life subscale (KOOS-QLS).

Results

During 2012 and 2015, 322 patients were treated because of patellar dislocation. Thirty-three patients had chondral or osteochondral fracture. Eleven patients (five males and six females) with a mean [standard deviation (SD)] age of 17.0 (6.5) years at the time of surgery met the inclusion criteria and were included. Five of the 11 patients had a subchondral and six an osteochondral fracture. Eight patients had a fracture in the patella and three in the femur. All patients had bony abnormalities in the knee. Nine out of 11 patients scored over 90/100 points on the Kujala scale and had good results on the Tegner scale [before surgery 5.0 (2.7) points versus after surgery 5.3 (1.6) points] and the KOOS-QLS [4.1 (4.2) points] outcome measures.

Conclusion

The removal or fixation of the fracture fragment combined with MPFL reconstruction is a feasible option in the treatment of symptomatic osteochondral or subchondral fragment in traumatic patellar dislocation. The short-term outcomes are encouraging.

Level of evidence: Level IV, retrospective case series.

Predictive Scoring for Recurrent Patellar Instability After a First-time Patellar Dislocation

PURPOSE

Patellofemoral instability is a common acute knee injury seen in the pediatric population. First-time patellar dislocations usually undergo conservative management, but ~15% to 80% of patients experience recurrent instability. This study aims to develop a prediction model using radiographic parameters of the patellofemoral joint seen on computed tomography scans in different degrees of knee flexion, to determine the risk of recurrence after the first episode of patellofemoral instability.

METHODS

A 12-year retrospective case-control study was performed. All patients in a single institution aged 18 years or younger who had a computed tomography patellar tracking scan performed for patellar instability were included. Predictors included in the score were determined through backward logistic regression and compared using receiver operating characteristic curve analysis.

RESULTS

This study revealed that recurrent dislocation in first-time patellofemoral dislocation could be accurately predicted using the prediction score that consisted of age, tibial tubercle-trochlear groove distance and congruence angle at 10- and 20-degree flexion. The sensitivity of the score was 100% and specificity was 73.3%. Three diagnostic zones were identified and used to categorize patients into low-, intermediate-, and high-probability groups.

CONCLUSION

This study presented a scoring system that incorporated radiographic knee kinematics in the risk assessment for recurrent patellofemoral instability for patient stratification. The scoring system could guide the decision for early surgical intervention after the first-episode patellofemoral dislocation for patients at high risk of recurrent patellofemoral dislocation.

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.

Lateral release associated with MPFL reconstruction in patients with acute patellar dislocation

Objective

Medial patellofemoral ligament (MPFL) injury occurs in the majority of the cases of acute patellar dislocation. The role of concomitant lateral retinaculum release with MPFL reconstruction is not clearly understood. Even though the lateral retinaculum plays a role in both medial and lateral patellofemoral joint stability in MPFL intact knees, studies have shown mixed clinical outcomes following its release during MPFL reconstruction surgery. Better understanding of the biomechanical effects of the release of the lateral retinaculum during MPFL reconstruction is warranted. We hypothesize that performing a lateral release concurrent with MPFL reconstruction will disrupt the patellofemoral joint biomechanics and result in lateral patellar instability.

Methods

A previously developed and validated finite element (FE) model of the patellofemoral joint was used to understand the effect of lateral retinaculum release following MPFL reconstruction. Contact pressure (CP), contact area (CA) and lateral patellar displacement were recorded. abstract.

Results

FE modeling and analysis demonstrated that lateral retinacular release following MPFL reconstruction with tibial tuberosity-tibial groove distance (TT-TG) of 12 mm resulted in a 39% decrease in CP, 44% decrease in CA and a 20% increase in lateral patellar displacement when compared to a knee with an intact MPFL. In addition, there was a 45% decrease in CP, 44% decrease in CA and a 21% increase in lateral displacement when compared to a knee that only had an MPFL reconstruction.

Conclusion

This FE-based analysis exhibits that concomitant lateral retinaculum release with MPFL reconstruction results in decreased PF CA, CP and increased lateral patellar displacement with increased knee flexion, which may increase the risk of patellar instability.

Combined MPFL reconstruction and tibial tubercle osteotomy for patellar instability: A retrospective review of 23 patients

The primary objective of this retrospective study is to compare patient outcomes following a combined approach (MPFL reconstruction and TTT) to outcomes reported in the literature by patients who required either only an isolated TTT procedure to treat pathologic lateral patellar instability or isolated MPFL reconstruction to treat patellar dislocation due to MPFL insufficiency. Twenty-three patients (74%) were available for follow-up and are included in our analysis. MPFL reconstruction combined with TTT has a high rate of success for patients presenting with patellar instability and extensor mechanism mal-alignment. The risk of recurrence with this technique was low (4.3%).

Predictors of Surgery and Cost of Care Associated with Patellar Instability in the Pediatric and Young Adult Population

Purpose

To determine how patient demographics, socioeconomic status, history of recurrence, and initial point of presentation for health care influenced the decision for surgical treatment following a patellar instability episode.

Methods

The New York SPARCS database from 2016 to 2018 was queried for patients aged 21 and younger who were diagnosed with a patellar instability episode. These were linked to later surgeries with Current Procedural Terminology (CPT) codes 27405 (MPFL repair), 27418 (tibial tubercle osteotomy), 27420 (dislocating patella reconstruction), 27422 (Campbell/Roux-Goldthwait procedure), and 27427 (extra-articular knee ligamentous reconstruction). χ²-analysis and binary logistic regression were used to assess demographic and injury-specific variables for association with operative management. A generalized linear model was used to estimate charges associated with patellar instability.

Results

There were 2,557 patients with patellar instability, 134 (5.2%) of whom underwent surgery. Patients with recurrent instability had 1.875 times higher odds of undergoing surgery (P = .017). Compared to white patients, black patients had 0.428 times the odds of surgery (P = .004). None of the patients without insurance had surgery. In the cost model, an initial visit to an outpatient office was associated with $1,994 lower charges compared to an emergency department (ED) visit (P < .001). Black patients had $566 more in charges than White patients (P = .009). Compared with nonoperative treatment, surgeries with CPT 27405 added $13,124, CPT 27418 added $10,749, CPT 27422 added $18,981, CPT 27420 added $23,700, and CPT 27427 added $25,032 (all P < .001).

Conclusions

Patients with recurrent instability had higher odds of surgery, while Black and uninsured patients had lower odds of surgery. ED visits were associated with significantly higher charges compared to office visits, and Black patients had higher charges than white patients. Minority and uninsured patients may face barriers in access to orthopedic care.

Level of Evidence

Level III, retrospective cohort study.

Comparing Nonoperative Treatment, MPFL Repair, and MPFL Reconstruction for Patients With Patellar Dislocation: A Systematic Review and Network Meta-analysis

Background:

Medial patellofemoral ligament (MPFL) reconstruction, MPFL repair, and nonoperative treatment are important treatments for patients with patellar dislocation. However, it is unclear which treatment leads to better outcomes.

Purpose:

To determine the efficacy and safety of the 3 treatments in the treatment of patellar dislocation and compare the effect of MPFL reconstruction with MPFL repair, MPFL reconstruction with nonoperative treatment, and MPFL repair with nonoperative treatment.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

The PubMed, Web of Science, Cochrane Library, Embase, CNKI (China National Knowledge Infrastructure), and Wanfang databases were searched from inception to December 2020. Included were clinical studies that described the efficacy and safety of 2 of the 3 treatments, studies directly comparing the clinical effects of the 2 operative techniques, or studies comparing the effects of reconstruction or repair with nonoperative treatment. Two reviewers independently extracted data and assessed the quality of the included studies with the Cochrane risk-of-bias tools. The outcomes evaluated were postoperative redislocation rate, revision rate, complications, and Kujala score. We used traditional direct pairwise meta-analysis as well as network meta-analysis for comprehensive efficacy of all 3 treatment measures.

Results:

Twelve studies were included: 5 compared MPFL reconstruction with MPFL repair, 2 compared MPFL reconstruction with nonoperative treatment, and 5 compared MPFL repair with nonoperative treatment. The risk of bias was serious in 4, moderate in 4 and low in 4 articles. MPFL reconstruction led to significantly reduced redislocation and improved Kujala scores compared with MPFL repair and nonoperative treatment. MPFL repair led to reduced redislocation rates compared with nonoperative treatment but did not show an obvious benefit in primary dislocations. There was no significant difference among the 3 treatments in terms of revision rate and incidence of complications, although we found that treatment-related complications were least likely to occur in nonoperative treatment.

Conclusion:

The results of this review indicate that MPFL reconstruction decreases recurrent dislocation compared with MPFL repair or nonoperative treatment, but it has a higher possibility of complications. MPFL repair resulted in less postoperative redislocation than nonoperative treatment but did not show an obvious benefit in primary dislocation.

Development of a Multivariable Model Based on Individual Risk Factors for Recurrent Lateral Patellar Dislocation

BACKGROUND

Nonoperative treatment after first-time patellar dislocation is the standard of care. There is evidence that certain patients may be at high risk for recurrent instability. The aim of this study was to develop a multivariable model to guide management of patients based on their individual risk of recurrent dislocation.

METHODS

A multivariable model was developed using 291 patients from 4 institutions to identify which patients were at higher risk for recurrent patellar dislocation within 2 years. This model was informed by a univariable logistic regression model developed to test factors based on the patient's history, physical examination, and imaging. The discriminatory ability of the model to classify who will or will not have a recurrent dislocation was measured using the area under the receiver operating characteristic curve (AUC).

RESULTS

Age, a history of a contralateral patellar dislocation, skeletal immaturity, lateral patellar tilt, tibial tubercle-trochlear groove (TT-TG) distance, Insall-Salvati ratio, and trochlear dysplasia were the most important factors for recurrent patellar dislocation. Sex, mechanism of injury, Caton-Deschamps ratio, sulcus angle, inclination angle, and facet ratio were not factors for recurrent dislocation. The overall AUC for the multivariable model was 71% (95% confidence interval [CI]: 64.7% to 76.6%).

CONCLUSIONS

Optimizing the management of lateral patellar dislocation will improve short-term disability from the dislocation and reduce the long-term risk of patellofemoral arthritis from repeated chondral injury. This multivariable model can identify patients who are at high risk for recurrent dislocation and would be good candidates for early operative treatment. Further validation of this model in a prospective cohort of patients will inform whether it can be used to determine the optimal treatment plan for patients presenting with an initial patellar dislocation. Until validation of the model is done with new patients, it should not be used in clinical practice.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The quantitative influence of current treatment options on patellofemoral stability in patients with trochlear dysplasia and symptomatic patellofemoral instability - a finite element simulation

BACKGROUND

Trochlear dysplasia is highly associated with patellofemoral instability. The goal of conservative and surgical treatment is to stabilize the patella while minimizing adverse effects. However, there is no literature investigating the quantitative influence of different treatment options on patellofemoral stability in knees with trochlear dysplasia. We created and exploited a range of finite element models to address this gap in knowledge.

METHODS

MRI data of 5 knees with trochlear dysplasia and symptomatic patellofemoral instability were adapted into this previously established model. Vastus medialis obliquus strengthening as well as double-bundle medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty were simulated. The force necessary to dislocate the patella by 10 mm and fully dislocate the patella was calculated in different flexion angles.

FINDINGS

Our model predicts a significant increase of patellofemoral stability at the investigated flexion angles (0°-45°) for a dislocation of 10 mm and a full dislocation after medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty compared to trochleodysplastic (P = 0.01) and healthy knees (P = 0.01-0.02). Vastus medialis obliquus strengthening has a negligible effect on patellofemoral stability.

INTERPRETATIONS

This is the first objective quantitative biomechanical evidence supporting the place of medial patellofemoral ligament reconstruction and medial patellofemoral ligament reconstruction combined with trochleoplasty in patients with symptomatic patellofemoral instability and trochlear dysplasia type B. Vastus medialis obliquus strengthening has a negligible effect on patellar stability at a low total quadriceps load of 175 N.

First-Time Acute Lateral Patellar Dislocation in Children and Adolescents: What About Unaffected Knee Patellofemoral Joint Anatomic Abnormalities?

Background and Objectives: Acute lateral patellar dislocation (LPD) is the most common acute knee disorder in children and adolescents, and may lead to functional disability. The purpose of this study was to identify key differences and correlations of the patellofemoral joint (PFJ) morphology between intact and contralateral injured knees in a first-time traumatic LPD population aged under 18 years. Materials and Methods: The data were gathered prospectively from a cohort of 58 patients (35 girls and 23 boys). The prevalence and combined prevalence of patella alta (PA) and trochlear dysplasia (TD) in both knees of patients were evaluated using X-ray by two radiologists. Results: The PFJ of patients' intact knees had a lower rate of TD (1.72% vs. 5.2%) and a less common combination of PA with shallow femoral sulcus (SFS) (22.4% vs. 44.8%) but more frequent PA (62.1% vs. 41.4%) compared with their injured knees. We noted statistically significant positive correlations (SSPCs) between the femoral sulcus angle (FSA) and PA in patients with intact (r = 0.37; p < 0.005) and contralateral injured knees (r = 0.33; p < 0.05). Conclusion: There were SSPCs between the FSA and PA in both gender and age groups of patients with intact and contralateral injured knees. The SSPCs between the FSA and PA of intact knees were higher in the patients with a more dysplastic PFJ anatomy (PA and TD) of the injured knees as compared to patients with only PA of the injured knees.

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.

MPFL reconstruction: indications and results

BACKGROUND AND AIM

The medial patellofemoral ligament (MPFL) is the most important structure commonly injured during lateral patellar dislocation and its rupture accounts for 3% of total knee injuries. MPFL reconstruction (MPFLR) is a reliable procedure with good results but variable rates of recurrent instability. The aim of this study is to underline the proper indications for the MPFLR reconstruction and to explain all the pearls and pitfalls regarding the MPFLR both in our experience and found in the latest literature.

METHODS

A comprehensive search in the latest literature using various combinations of the keywords MPFL, MPFLR, dislocation, treatment was performed. The following data were extracted: diagnosis methods, indications and contraindications for isolated MPFLR, type of management, recurrence of instability, outcomes and complications.

RESULTS

History of multiple patellar dislocations is the most relevant indication for ligament reconstruction especially after a failed course of conservative treatment in presence of persistent patello-femoral instability. Gold standard technique for MPFLR has not been clearly defined yet.

CONCLUSIONS

There is still poor literature about outcome comparisons, therefore it is challenging to decide which technique is the most appropriate as surgical procedures are continuously developing. The ideal candidates for MPFLR have to be decided after a throughout evaluation and careful planning and, with nowadays knowledge, it is possible to put indication for a reconstruction exposing the patient to minimal risks.

Surgical treatment is better than non-surgical treatment for primary patellar dislocation: a meta-analysis of randomized controlled trials

BACKGROUND

At present, the best treatment for primary patellar dislocation (PPD) has not been unified. Moreover, meta-analyses comparing the non-surgical and surgical treatments of PPD are lacking. Thus, we aimed to compare the clinical efficacy of surgical or non-surgical treatment of PPD.

METHODS

Randomized controlled studies of surgical and non-surgical treatments of PPD from 1966 to 2018 were retrieved from the following databases: PubMed, EMBASE, Cochrane Library, Wanfang Database, China Knowledge Network, Google Scholar, and Weipu Database. We screened for literature that met the inclusion criteria and extracted useful data for our meta-analysis.

RESULTS

Nine studies, involving 492 patients, met the inclusion criteria and were analyzed in this study. The recurrence rate of patellar dislocation in the surgical group was lower than that in the non-surgical group (P = 0.04]). Subgroup analysis according to the follow-up time showed that the Kujala score (P < 0.001) and lower recurrence rate of dislocation (P = 0.05) than the non-surgical group in the short term. Subgroup analysis according to surgical year showed that the surgical group get higher Kujala score (P < 0.001) and lower recurrence rate of dislocation (P = 0.01) than the non-surgical group in recent years.

CONCLUSION

Surgical treatment can provide better clinical results in a short period of time, and patients may achieve good results within 10 years owing to the advances in surgical techniques and instruments. Thus, we recommend surgical treatment as the preferred treatment for primary patellar dislocation.

Scoring system for optimal management of acute traumatic patellar dislocation: A multicenter study

BACKGROUND

In first-time acute traumatic patellar dislocations, numerous anatomic and clinical factors are complicatedly associated and should be comprehensively considered for the optimal management of conservative or surgical intervention. The purpose of this study was to establish a scoring system, using a concept that is not complicated and easily used in clinic.

METHODS

Of 131 first-time acute traumatic patellar dislocations, 81 patients (51 females, 30 males) with an average age of 19.6 (95%CI, 17.5-21.6) years and an average follow-up duration of 17.1 (95% CI, 12.3-21.9) months, who underwent conservative treatment after first-time dislocations, were reviewed. Based on the odds ratios applying logistic regression analysis, the scoring system was established.

RESULTS

The scoring system (total: 10 points) had simple composition of age <20 (2 points), sports injury (1 points), hemarthrosis (1 points), and image findings of a bony fragment (3 points), lateral shift of the patella (1 points), and trochlear dysplasia (2 points). A threshold score of 6.5 was determined using the area under receiver operating characteristic curve of 0.893 (p < 0.0001). In logistic regression analysis, a score of ≥7 was shown to be a dominant factor for recurrence (OR = 27.1, p < 0.0001). Furthermore, the association between the score and recurrence risk was as follows: a score of ≤4 = low risk (1/21 cases, 5%); a score of 5-7 = medium risk (13/27 cases, 48%); a score of ≥8 = high risk (30/33 cases, 91%).

CONCLUSIONS

Based on the simple scoring system, patients who scored ≥8 were considered suitable for surgical treatment because of the high rate of recurrence, whereas those who scored ≤4 were considered suitable for conservative treatment because of the low rate of recurrence.

Management of the First Patellar Dislocation: A Narrative Review

First patellar dislocation is a common injury of the knee, involving often adolescents and the active population. The consequences of the first episode can be various and potentially disabling. Among these, acute patellar dislocation can often result in recurrent patellar instability. Recurrent patellar instability is certainly multifactorial but depends primarily on the injury of the medial patellofemoral ligament (MPFL), the major soft-tissue stabilizer of the patella. Some classifications are extremely useful in establishing the diagnosis and therapy in patellofemoral disease, in particular in terms of instability. Among those, Henri Dejour and WARPS (weak atraumatic risky anatomy pain and subluxation)/STAID (strong traumatic anatomy normal instability and dislocation) classifications are certainly the most frequently used. There is no clear agreement on the management of the first patellar dislocation. A conservative approach seems to be the first choice in most of cases, but the presence of patellar displacement or osteochondral fractures makes surgery mandatory at the beginning. In addition, there is no clear consensus on which surgical strategy should be used to approach first dislocation, in relation to the possible variation in location of the MPFL injury, and to the eventual presence of preexisting predisposing factors for patellar instability. MPFL reconstruction may theoretically be more reliable than repair, while there is no clear evidence available that osseous abnormality should be addressed after the first episode of patellar dislocation. A narrative review was conducted to report the etiology, the diagnosis and all the possible treatment options of the first patellar dislocation. Modern classifications of the patellofemoral instability were also presented.

Surgical versus nonsurgical treatment of primary acute patellar dislocation: A systematic review and meta-analysis

BACKGROUND

To systematically review the efficacy of surgical versus nonsurgical treatment for acute patellar dislocation.

MATERIALS AND METHODS

PubMed, Cochrane, and Embase were searched up to February 12, 2019. After removing duplicates, preliminary screening, and reading the full texts, we finally selected 16 articles, including 11 randomized controlled trials and 5 cohort studies. The quality of the enrolled studies was evaluated by Jadad score or Newcastle-Ottawa scale. Meta-analyses were performed using odds ratio (OR) and standardized mean difference (SMD) as effect variables. The clinical parameters assessed included mean Kujala score, rate of redislocation, incidence of patellar subluxation, patient satisfaction, and visual analog scale (VAS) for pain. Evidence levels were determined using GRADE profile.

RESULTS

The 16 included studies involved 918 cases, 418 in the surgical group and 500 in the nonsurgical group. The results of the meta-analysis showed higher mean Kujala score (SMD = 0.79, 95% confidence interval [CI] [0.3, 1.28], P = .002) and lower rate of redislocation (OR = 0.44, 95% CI [0.3, 0.63], P < .00001) in the surgical group than the nonsurgical group, but showed insignificant differences in the incidence of patellar subluxation (OR = 0.61, 95% CI [0.36, 1.03], P = .06), satisfaction of patients (OR = 1.44, 95% CI [0.64, 3.25], P = .38), and VAS (SMD = 0.84, 95% CI [-0.36, 9.03], P = .84).

CONCLUSION

For patients with primary acute patellar dislocation, surgical treatment produces a higher mean Kujala score and a lower rate of redislocation than nonsurgical treatment.

Clinical outcomes after absorbable suture fixation of patellar osteochondral fracture following patellar dislocation

Background

Osteochondral fracture (OCF) is one of the severe complications following a patellar dislocation. The appropriate fixation method for patients with OCF remains controversial.

Methods

Eighteen patients who had undergone surgery after a patellar dislocation were recruited retrospectively. Patellar OCF was fixed with an absorbable suture in an unreported method. The medial patellofemoral ligament (MPFL) was repaired or reconstructed if necessary. The Lysholm and Kujala knee scoring systems were used to evaluate the knee function. Imaging examinations were used to confirm the fracture healing.

Results

The mean period of follow-up was 36 months. All patients recovered well postoperatively without symptomatic complications. The Lysholm score and the Kujala score improved significantly from 37.6 (SD =6.8) and 45.9 (SD =6.4) preoperatively to 80.9 (SD =7.4) and 89.4 (SD =6.8) postoperatively at the latest follow-up, respectively. Imaging evidence including X-ray and MRI revealed good healing of the OCFs.

Conclusions

This study showed satisfactory mid-term outcomes of OCF fixation using absorbable suture, which supports this method's potential to be a novel surgical method in the treatment of patellar OCF caused by a patellar dislocation.

Anatomic patellar instability risk factors in primary lateral patellar dislocations do not predict injury patterns: an MRI-based study

PURPOSE

The primary goal was to describe the injury patterns in a population of primary (first time) lateral patellar dislocators (LPD) to lend clarity to commonly held notions about injury patterns in this population.

METHODS

A prospective study identifying patients presenting with LPD between 2008 and 2012. Inclusion criteria were a history and physical exam consistent with primary LPD, and an MRI consistent with the diagnosis without other significant ligamentous injury. On MRI, location of cartilage, medial patellofemoral ligament (MPFL) injury, and bone bruising were noted. Severity was categorized as partial or complete for MPFL and cartilage lesions. Anatomic patellar instability risk factors (patella alta, trochlear dysplasia, increased TT-TG, and lateral patella tilt) were recorded and compared to the injury patterns.

RESULTS

This study involved 157 patients; 107 patients were skeletally mature. Of the 157 patients, 26 had surgery for this injury due to clinician-perceived need for cartilage debridement. MPFL injury severity was complete rupture (N = 69, 44%), partial (N = 67, 43%), and none (N = 19, 13%). MPFL injury location was isolated femoral (N = 16, 10%), isolated patella (N = 26, 17%), isolated mid-substance (0%), multiple locations (N = 95, 61%), and none (N = 20, 13%). Chondral injury location was patella (N = 67, 43%), lateral femoral condyle (N = 11, 7%), multiple locations (N = 53, 34%), and none (N = 26, 17%). A majority (61%) of patellar chondral lesions were at its inferomedial aspect; all medial patellar retinacular partial injuries involved the inferomedial aspect of the patella, consistent with the insertion of the medial patellotibial ligament (MPTL). Skeletally immature patients had a greater risk of isolated patellar MPFL and chondral injury. No clear relationship was found between/across the location and/or severity of bone bruising, MPFL, or chondral injury.

CLINICAL RELEVANCE

Underlying anatomic patellar instability risk factors defined by MRI, do not predict injury patterns. MPFL and chondral injury, as well as bone bruising, are common following LPD. The medial patellotibial ligament is torn in patellar-based medial retinacular injuries, based on MRI injury location. Skeletal immaturity plays a role in the location of the injury pattern with isolated patellar-based MPFL/chondral injury being more common in the skeletally immature patient. Sex does not appear to be a factor in injury patterns after primary LPD. Knowledge of these injury trends will help focus the clinician in injury evaluation when managing primary patellar dislocations.

LEVEL OF EVIDENCE

Case series, Level IV.

The Correlation between the Injury Patterns of the Medial Patellofemoral Ligament in an Acute First-Time Lateral Patellar Dislocation on MR Imaging and the Incidence of a Second-Time Lateral Patellar Dislocation

Objective

To evaluate the correlation between the injury patterns of the medial patellofemoral ligament (MPFL) on magnetic resonance imaging in an acute first-time lateral patellar dislocation (LPD) and incidence of a second-time LPD.

Materials and Methods

Magnetic resonance images were prospectively analyzed in 147 patients after an acute first-time LPD with identical nonoperative management. The injury patterns of MPFL in acute first-time LPDs were grouped by location and severity for the analysis of the incidence of second-time LPD in a 5-year follow-up. Independent t tests, chi-square tests and Kruskal-Wallis tests were performed as appropriate.

Results

Forty-six cases (46/147, 31.3%) of second-time LPD were present at the 5-year follow-up. Fourteen (14/62, 22.6%) and 31 cases (31/80, 38.8%) were present in the partial and complete MPFL tear subgroups, respectively. Twenty-five cases (25/65, 38.5%), 11 cases (11/26, 42.3%), and 8 cases (8/47, 17%) were present in the isolated femoral-side MPFL tear (FEM), combined MPFL tear (COM), and isolated patellar-side MPFL tear (PAT) subgroups, respectively. Compared with the partial MPFL tears, complete tears showed higher incidence of a second-time LPD (p = 0.04). The time interval between the two LPDs was shorter in the complete MPFL tear subgroup (24.2 months) than in the partial tear subgroup (36.9 months, p = 0.001). Compared with the PAT subgroup, the FEM and COM subgroups showed a higher incidence of a second-time LPD (p = 0.025). The time intervals between the two LPDs were shorter in the FEM and COM subgroups (20.8 months and 19.2 months) than in the PAT subgroup (32.5 months, p = 0.049).

Conclusion

A complete MPFL tear, isolated femoral-side tear and combined tear in a first-time LPD predispose a second-time LPD.

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

BACKGROUND

Immobilization devices such as plaster splints, casts and braces have been used for first time patellar dislocation (FTPD) in order to prevent redislocation. This study evaluates different non-operative immobilization regimes upon rates of redislocation.

METHODS

A retrospective cohort study with a study population of 1366 in which 601 subjects under 30years with FTPD were included from three hospitals. Exclusion criteria were osteochondral fracture, ligament injury and subluxation. Subjects were divided into five groups; unknown/none, two weeks of brace, two weeks of brace followed by bandage, four weeks of brace and six weeks of brace with increasing of range of motion. Radiographs were evaluated for trochlear dysplasia (TD), patella alta, trochlear depth and growth zone. Crude analysis and logistic regression adjusted for radiographic assessments, age, gender and rehabilitation was done in STATA® with significance p≤0.05.

RESULTS

Forty-five point eight percent were between 15 and 19years and 51.4% were male. One hundred sixty-three experienced redislocation (27.1%). Logistic regression was performed at 404 subjects and showed that rehabilitation, gender, TD, patella alta, and growth zone had no significant odds ratio (OR) on redislocation. The duration of brace demonstrated no significant OR in reducing redislocation. Subjects between 20 and 29years showed lower OR in redislocation (95% CI) of 0.27 (0.11; 0.64, p=0.003).

CONCLUSION

This study demonstrated no difference in duration of brace treatment in reducing patella redislocation after FTPD. Rehabilitation and predisposal factors such as TD, trochlear depth, patella alta and open growth zone did not influence the redislocation rate. Increasing age reduced risk of redislocation.

Economic Decision Model for First-Time Traumatic Patellar Dislocations in Adolescents

BACKGROUND

The surgical management of traumatic patellar dislocations in adolescents is associated with a lower rate of recurrent dislocations compared with nonoperative care. However, the attendant cost of surgery and the quality-of-life benefit of a surgical treatment strategy are unclear.

PURPOSE

To compare the cost-utility of 3 management strategies for acute first-time patellar dislocations in adolescents: (1) nonoperative treatment only, (2) initial nonoperative treatment with surgery only for recurrent dislocations, and (3) immediate surgery.

STUDY DESIGN

Economic and decision analysis; Level of evidence, 2.

METHODS

A 10-year state-transition Markov model was constructed to compare the cost-utility of the 3 index treatment protocols. Utilities used to define health states were derived from a telephone interview of 60 adolescents with a history of acute patellar dislocations. The probability of transition between each health state was informed by the available literature. Direct costs were estimated using a statewide ambulatory surgery database, and indirect costs were estimated based on parental lost productivity. Effectiveness was expressed in quality-adjusted life years (QALYs). The principal outcome measure was the incremental cost-effectiveness ratio (ICER).

RESULTS

In the base case for our model, nonoperative treatment only was the least costly ($7300) but also the least effective (5.30 QALYs); initial nonoperative treatment with delayed surgery cost $10,500 for a 5.93 QALY benefit, while immediate surgical treatment cost $17,100 and provided 6.32 QALY benefits. Compared with nonoperative treatment only, initial nonoperative treatment with delayed surgery was associated with an ICER of $5100 per QALY. When immediate surgery was compared with a strategy of delayed surgery, immediate surgery provided incremental benefits at an ICER of $17,000 per QALY. The model was sensitive to the probability of surgical versus nonoperative treatment to achieve a full return to preinjury activity versus an intermediate lower state. When the probability of achieving a full return to preinjury activity with initial nonoperative treatment exceeds 47.5% (compared with 34.2% in the base case), then initial nonoperative treatment with delayed surgery is preferred to immediate surgery. Similarly, when the probability of achieving a full return to full preinjury activity with surgery falls below 51% (compared with 64% in the base case), then delayed surgery after initial nonoperative treatment is preferred.

CONCLUSION

Immediate surgery and delayed surgical treatment are both cost-effective treatment options; however, immediate surgical treatment provides the highest QALY gains within a 10-year time horizon. Our model sensitivity analysis highlights the role of optimizing functional and quality-of-life benefits in the treatment of acute traumatic patellar dislocations. These findings have implications for clinical guidelines and policy decisions relating to adolescent patellar dislocations.

Traumatic Patellar Dislocation and Cartilage Injury: A Follow-up Study of Long-Term Cartilage Deterioration

BACKGROUND

Patellofemoral cartilage deterioration and osteoarthritis are reported to be associated with recurrent patellar dislocation. However, the association between first-time traumatic patellar dislocation and cartilage deterioration is unknown.

PURPOSE

The aim of this study was to assess long-term cartilage deterioration in the patellofemoral and tibiofemoral joint after conservatively treated traumatic lateral patellar dislocation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty patients (mean age, 25 years) who sustained first-time traumatic lateral patellar dislocation with no previous patellofemoral instability symptoms were initially scanned with 1.5-T magnetic resonance imaging (MRI). A follow-up 3-T MRI was conducted, on average, 8 years after first-time lateral patellar dislocation. Subjective instability symptoms and Knee injury and Osteoarthritis Outcome Score were also assessed.

RESULTS

In the primary MRI, patellofemoral cartilage injury was seen in 14 of 20 patients (70%). Most (14/15) of the injuries were seen in the patellar cartilage, especially at the medial facet. On the follow-up MRI, patellofemoral cartilage deterioration was visible for all patients. The central patella ( P = .005) seemed especially prone to cartilage deterioration during the follow-up. Half of the patients (10/20) had grade 3-4 cartilage lesions in the patellofemoral joint in the follow-up MRI. In the primary MRI, only 1 patient exhibited tibiofemoral joint cartilage lesions, whereas at the time of follow-up, 10 of 20 patients exhibited tibiofemoral cartilage lesions. The majority of these lesions were considered clinically nonsignificant (International Cartilage Repair Society = 1) and were seen in the lateral compartment (6/10, 60%). Of the 14 patients (36%) with injury to the patellar cartilage, 5 reported subsequent instability of the patellofemoral joint, but this was not associated with more significant cartilage deterioration in the follow-up MRI compared with patients without redislocation.

CONCLUSION

While recurrent lateral patellar dislocation is known to lead to degenerative process, a single first-time or infrequently recurring traumatic lateral patellar dislocation also seems to be associated with gradual cartilage deterioration. Traumatic lateral patellar dislocation might initiate gradual degeneration of the cartilage in the patellofemoral joint and can lead to the development of generalized knee osteoarthritis. Instability symptoms of the patellofemoral joint, however, were not related to the severity of the deterioration.

Pediatric patellar dislocation

Acute patellar dislocation affects approximately 1:1000 healthy children 9-15 years of age, and up to 50% are at risk for recurrent dislocations. In adults the condition is associated with long-term complications, such as osteoarthritis and impairment of knee function. However, literature describing the outcome in a pediatric population is sparse. The present review article evaluates the long-term effects on knee function and cartilage quality after traumatic patellar dislocation in childhood, and also to evaluate the reliability of two clinical tests of medio-lateral knee position, in healthy children.

Predictors of Recurrent Patellar Instability in Children and Adolescents After First-time Dislocation

BACKGROUND

Patellar dislocations are one of the most common knee injuries in children and adolescents and are challenging to treat. Recurrence rates are relatively high and many patients have functional limitations, even in the absence of a recurrent instability episode. The purpose of this study was to examine the risk factors in patients with first-time patellofemoral dislocations to develop a prediction model of recurrence.

METHODS

A single institution retrospective review of all patients with a first-time patellofemoral dislocation from 2002 to 2013 was performed. Demographic risk factors (age, sex, laterality, mechanism of injury, and history of contralateral patellar dislocation) and radiographic risk factors (increased patella height, trochlear dysplasia, and skeletal immaturity) were examined. Patella height was measured using Caton-Deschamps index (CDI). Trochlear dysplasia was assessed using the 2-grade Dejour classification and skeletal immaturity was assessed based on the distal femur and proximal tibia physis (open, closing, or closed).

RESULTS

In total, 266 knees in 250 patients were included in the study. Of these, 222 (83.5%) were treated nonoperatively and 44 (16.5%) were treated surgically. Of the knees treated nonoperatively, 77 (34.7%) had a recurrence. Significant risk factors for recurrence on univariate analysis were age 14 years and below, history of contralateral patellar dislocation, trochlear dysplasia, skeletal immaturity, and a CDI>1.45. Multivariate analysis was performed and trochlear dysplasia and skeletal immaturity were the most significant factors with odds ratios of 3.56 and 2.23, respectively. The presence of all 4 multivariate risk factors (CDI>1.45, history of contralateral patellar dislocation, trochlear dysplasia, and skeletal immaturity) had a predicted risk of recurrence of 88%. The presence of any 3 risk factors had a predicted risk of about 75% and the presence of any 2 risk factors had a predicted risk of about 55%.

CONCLUSIONS

Trochlear dysplasia, skeletal immaturity, CDI>1.45, and a history of contralateral patellar dislocation were all significant risk factors for recurrence in patients with first-time patellar dislocations. A predictive model for calculation of recurrence risk was developed for any combination of the different risk factors. This information is useful when counseling patients and their families after first-time patellar dislocation about prognosis and potential outcomes.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

Injury patterns of medial patellofemoral ligament after acute lateral patellar dislocation in children: Correlation analysis with anatomical variants and articular cartilage lesion of the patella

OBJECTIVES

To assess the relationship between injury patterns of medial patellofemoral ligament (MPFL) and anatomical variants and patellar cartilage lesions after acute lateral patellar dislocation (LPD) in children.

METHODS

MR images were obtained in 140 children with acute LPD. Images were acquired and evaluated using standardised protocols.

RESULTS

Fifty-eight cases of partial MPFL tear and 75 cases of complete MPFL tear were identified. Injuries occurred at an isolated patellar insertion (PAT) in 52 cases, an isolated femoral attachment (FEM) in 42 cases and an isolated mid-substance (MID) in five cases. More than one site of injury was identified in 34 cases. Compared with Wiberg patellar type C, Wiberg patellar type B predisposed to complete MPFL tear (P = 0.042). No correlations were identified between injury patterns of MPFL and trochlear dysplasia, patellar height and tibial tuberosity-trochlear groove distance (P > 0.05). Compared with partial MPFL tear, complete MPFL tear predisposed to Grade-IV and Grade-V patellar chondral lesion (P = 0.02). There were no correlations between incidence of patellar cartilage lesion and injury locational-subgroups of MPFL (P = 0.543).

CONCLUSIONS

MPFL is most easily injured at the PAT in children. Wiberg patellar type B predisposes to complete MPFL tear. Complete MPFL tear predisposes to a higher grade of patellar chondral lesion.

KEY POINTS

• MPFL is most easily injured at its patellar insertion in children. • Wiberg patellar type B predisposes to complete MPFL tear. • No correlations between injury patterns of MPFL and other three anatomical variants. • Complete MPFL tear predisposes to higher grade patellar chondral lesion. • No correlations between injury locations of MPFL and patellar cartilage lesion.

Imaging assessment of patellar instability and its treatment in children and adolescents

Transient patellar dislocation is a common entity in children and adolescents, characterized by lateral dislocation of the patella, usually with spontaneous reduction. Many predisposing conditions have been described, including trochlear dysplasia, excessive lateral patellar tilt, patella alta and lateralization of the tibial tuberosity. Associated injuries are bone bruises of the patella and lateral femoral condyle, tears of the medial retinaculum that include the medial patellofemoral ligament (MPFL), tears of the vastus medialis obliquus muscle, injuries of articular cartilage, and intra-articular bodies. Children who are refractory to conservative management, have a large cartilage defect, or are at substantial risk for recurrent dislocations are candidates for surgical procedures to prevent future dislocations. Procedures can include MPFL repair or reconstruction, tibial tubercle repositioning and lateral retinacular release. The purpose of this review is to illustrate the imaging findings of transient patellar dislocation in the acute setting, the normal imaging appearance after surgical intervention, and post-surgical complications.

Management of Acute Patellar Dislocation: A Case Report

OBJECTIVE

The purpose of this case study is to describe the evaluation and management of patellar dislocations and the different approaches used from providers in different countries.

CLINICAL FEATURES

An individual dislocated her left patella while traveling abroad and received subsequent care in Thailand, China, and the United States.

INTERVENTION AND OUTCOME

Nonoperative treatment protocols including manual closed reduction of the patella, casting of the leg, and rehabilitation exercises were employed.

CONCLUSION

Receipt of care when abroad can be challenging. The patient's knee range of motion and pain continued to improve when she was diligent about performing the home exercise program. This case highlights the importance of a thorough examination, a proper regimen of care, and patient counseling to ensure a full recovery and minimize the chance of re-injury.

Multiligamentous injuries and knee dislocations

Complex capsular ligamentous structures contribute to stability of the knee joint. Simultaneous injury of two or more knee ligaments, aside from concurrent tears involving the anterior cruciate and medial collateral ligaments, is considered to be associated with femorotibial knee dislocations. Proximal tibiofibular joint dislocations are not always easily recognized and may be overlooked or missed. Patellofemoral dislocations can be transient with MR imaging sometimes required to reach the diagnosis. In this article, the authors describe the mechanism of injury, ligamentous disruptions, imaging, and treatment options of various types of knee dislocations including injuries of the femorotibial, proximal tibiofibular, and patellofemoral joints.

Anatomy of the Medial Patello-Femoral Ligament: a systematic review of the last 20 years literature

BACKGROUND

Although many studies have investigated the anatomy of the Medial Patello-Femoral Ligament (MPFL), some studies have even questioned its existence. In the last 20 years, there is a renewed interest on the role of the MPFL in patello-femoral instability. As a result, several studies have been published that describe the anatomy, function and possible surgical reconstruction of the MPFL. Despite the large amount of literature produced, there is still a lack of consensus on what is its real anatomy as there are currently no systematic reviews on this topic.

PURPOSES

Thus, the aim of this review is to systematically report the results in literature regarding in anatomical papers, the existence, size, insertion sites and relationships of this ligament with the other medial structures of the knee.

METHODS

We have systematically analyzed anatomical studies currently available in literature between 1980 and December 2012. The search was carried out on Medline, Embase, Cochrane Library and Google Scholar. We checked reference lists of articles, reviews and textbooks identified by the search strategy for other possible relevant studies.

RESULTS

The outcomes examined are the presence of the ligament, its size (length, width, thickness), and its patellar and femoral insertions. A total of 312 cadaveric knees were included in the 17 studies; the MPFL was identified in 99% of cases (309).

CONCLUSIONS

The consensus is that the MPFL is almost always present in the dissected knees. The size and insertions of the ligament demonstrate great variation between cadavers.

LEVEL OF EVIDENCE

Systematic review of anatomical study, Level 1.

Surgical versus conservative treatment of primary patellar dislocation. A systematic review and meta-analysis

PURPOSE

The purpose of this study was to determine the efficacy of surgical and conservative treatment in the prevention of recurrence after primary patellar dislocation.

METHODS

Studies were searched on MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and CINHAL from their inception to April 2015. All randomized controlled clinical trials comparing surgical versus conservative treatment after first patellar dislocation were included. Primary outcomes were: recurrent dislocation, subluxation, overall instability and subsequent surgery. Secondary outcomes included imaging, and subjective and objective clinical assessment tools. Methodological quality of the studies was assessed using Cochrane Collaboration's "Risk of Bias" tool. Pooled analyses were reported as risk ratio (RR) using a random effects model. Continuous data were reported as standardized mean difference (SMD) and 95 % confidence intervals (CIs). Heterogeneity was assessed using I².

RESULTS

Nine studies were included in the meta-analyses. Methodological quality of the studies was moderate to low. Meta-analyses showed that surgical treatment significantly reduces the redislocation rate (RR = 0.62; 95% CI = 0.39, 0.98, p = 0.04) and provides better results on Hughston VAS score (SMD = -0.32; 95% CI = -0.61, -0.03; p = 0.03) and running (OR = -0.52; 95% CI = 0.31, 0.88; p = 0.01). Conservative treatment showed less occurrence of minor complications (OR = 3.46; 95% CI = 2.08, 5.77; p = 0.01) and better results in the figure-of-8 run test (SMD = 0.42; 95% CI = 0.06, 0.77; p = 0.02) and in the squat down test (SMD = -0.45; 95% CI = -0.81, -0.10; p < 0.00001). No other significant differences could be found.

CONCLUSIONS

Based on the available data, surgical treatment of primary patella dislocation significantly reduces the risk of patella redislocation.

Surgical versus non-surgical interventions for treating patellar dislocation

BACKGROUND

Patellar dislocation occurs when the patella disengages completely from the trochlear (femoral) groove. Following reduction of the dislocation, conservative (non-surgical) rehabilitation with physiotherapy may be used. Since recurrence of dislocation is common, some surgeons have advocated surgical intervention rather than non-surgical interventions. This is an update of a Cochrane review first published in 2011.

OBJECTIVES

To assess the effects (benefits and harms) of surgical versus non-surgical interventions for treating people with primary or recurrent patellar dislocation.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group's Specialised Register, the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, AMED, CINAHL, ZETOC, Physiotherapy Evidence Database (PEDro) and a variety of other literature databases and trial registries. Corresponding authors were contacted to identify additional studies. The last search was carried out in October 2014.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled clinical trials evaluating surgical versus non-surgical interventions for treating lateral patellar dislocation.

DATA COLLECTION AND ANALYSIS

Two review authors independently examined titles and abstracts of each identified study to assess study eligibility, extract data and assess risk of bias. The primary outcomes we assessed were the frequency of recurrent dislocation, and validated patient-rated knee or physical function scores. We calculated risk ratios (RR) for dichotomous outcomes and mean differences MD) for continuous outcomes. When appropriate, we pooled data.

MAIN RESULTS

We included five randomised studies and one quasi-randomised study. These recruited a total of 344 people with primary (first-time) patellar dislocation. The mean ages in the individual studies ranged from 19.3 to 25.7 years, with four studies including children, mainly adolescents, as well as adults. Follow-up for the full study populations ranged from two to nine years across the six studies. The quality of the evidence is very low as assessed by GRADE (Grading of Recommendations Assessment, Development and Evaluation Working Group) criteria, with all studies being at high risk of performance and detection biases, relating to the lack of blinding.There was very low quality but consistent evidence that participants managed surgically had a significantly lower risk of recurrent dislocation following primary patellar dislocation at two to five years follow-up (21/162 versus 32/136; RR 0.53 favouring surgery, 95% confidence interval (CI) 0.33 to 0.87; five studies, 294 participants). Based on an illustrative risk of recurrent dislocation in 222 people per 1000 in the non-surgical group, these data equate to 104 fewer (95% CI 149 fewer to 28 fewer) people per 1000 having recurrent dislocation after surgery. Similarly, there is evidence of a lower risk of recurrent dislocation after surgery at six to nine years (RR 0.67 favouring surgery, 95% CI 0.42 to 1.08; two studies, 165 participants), but a small increase cannot be ruled out. Based on an illustrative risk of recurrent dislocation in 336 people per 1000 in the non-surgical group, these data equate to 110 fewer (95% CI 195 fewer to 27 more) people per 1000 having recurrent dislocation after surgery.The very low quality evidence available from single trials only for four validated patient-rated knee and physical function scores (the Tegner activity scale, KOOS, Lysholm and Hughston VAS (visual analogue scale) score) did not show significant differences between the two treatment groups.The results for the Kujala patellofemoral disorders score (0 to 100: best outcome) differed in direction of effect at two to five years follow-up, which favoured the surgery group (MD 13.93 points higher, 95% CI 5.33 points higher to 22.53 points higher; four studies, 171 participants) and the six to nine years follow-up, which favoured the non-surgical treatment group (MD 3.25 points lower, 95% CI 10.61 points lower to 4.11 points higher; two studies, 167 participants). However, only the two to five years follow-up included the clear possibility of a clinically important effect (putative minimal clinically important difference for this outcome is 10 points).Adverse effects of treatment were reported in one trial only; all four major complications were attributed to the surgical treatment group. Slightly more people in the surgery group had subsequent surgery six to nine years after their primary dislocation (20/87 versus 16/78; RR 1.06, 95% CI 0.59 to 1.89, two studies, 165 participants). Based on an illustrative risk of subsequent surgery in 186 people per 1000 in the non-surgical group, these data equate to 11 more (95% CI 76 fewer to 171 more) people per 1000 having subsequent surgery after primary surgery.

AUTHORS' CONCLUSIONS

Although there is some evidence to support surgical over non-surgical management of primary patellar dislocation in the short term, the quality of this evidence is very low because of the high risk of bias and the imprecision in the effect estimates. We are therefore very uncertain about the estimate of effect. No trials examined people with recurrent patellar dislocation. Adequately powered, multi-centre, randomised controlled trials, conducted and reported to contemporary standards, are needed. To inform the design and conduct of these trials, expert consensus should be achieved on the minimal description of both surgical and non-surgical interventions, and the anatomical or pathological variations that may be relevant to both choice of these interventions and the natural history of patellar instability. Furthermore, well-designed studies recording adverse events and long-term outcomes are needed.

A biomechanical approach to interpreting magnetic resonance imaging of knee injuries

This article discusses common injury mechanisms and the subsequent constellation of magnetic resonance (MR) imaging findings in the knee following trauma in the context of instability, as distinguished by the degree of knee flexion and tibial rotation at the time of initial injury, in addition to the direction and magnitude of the responsible force vectors. Using 3-dimensional imaging, common injury mechanisms are illustrated and correlated with MR imaging findings of the resulting osteochondral, ligamentous, meniscal, and musculotendinous lesions. The most common classification and grading systems for these individual lesions and their subsequent treatment implications are discussed.

Magnetic resonance imaging of the extensor mechanism

Anterior knee pain is associated with many different causes. The clinical diagnosis may be unclear when the patient initially presents for evaluation. Magnetic resonance (MR) imaging is a valuable modality with high diagnostic accuracy in the evaluation of extensor mechanism pathology, which commonly presents with anterior knee pain. The most common disorders include patellar fracture, patellofemoral tracking abnormalities, tendon trauma and degeneration. These injuries manifest with characteristic patterns on MR imaging. This article discusses normal anatomy, common injuries, and diagnostic pitfalls on MR imaging.

Shape and size of the medial patellofemoral ligament for the best surgical reconstruction: a human cadaveric study

PURPOSE

The aim of this study was to investigate the shape and the attachments of the medial patellofemoral ligament (MPFL) in cadaver specimens to determine an anatomical basis for the best MPFL reconstruction.

METHODS

Twenty fresh-frozen knees were used. Dissection protocol implied performing dissections from within the knee joint. We investigated the shape and the attachments between the MPFL and the quadriceps tendon, the patellar and femur insertions, and all the other relationships with the medial soft tissues of the knee.

RESULTS

The distal fibers of MPFL were interdigitated with the deep layer of the medial retinaculum. All isolated ligament had a sail-like shape with the patellar side bigger than the femoral side. The femoral insertion, distinct both from medial epicondyle and adductor tubercle, was located at 9.5 mm (range 4-22) distal and anterior respect to adductor tubercle and proximal and posterior to epicondyle. The medial third of the thickness of patella was involved in the insertion. The proximal third of the patella is always involved in the MPFL attachment; in 45% of the cases, it was extended to the medial third and in one case, an extension at the distal third was found. Additionally in 35% (7 cases), it extended to the quadriceps tendon and it were inconstantly attached at the vastus medialis obliques (VMO) tendon and at the vastus intermedius (VI) tendon in an aponeurotic structure.

CONCLUSIONS

The MPFL is a distinct structure that goes from patella to femur with a sail-like shape; its patellar insertion, that mostly occur via an aponeurosis tissue with VMO and VI, is at the proximal third of the patella but it may extend in some cases to the medial third patella or to the quadriceps tendon, or very rarely to the distal third of the patella. In the femoral side, the MPFL is inserted in its own site, in most cases distinct both from epicondyle and adductor tubercle, located on average at a 9.5 mm distance distally and anteriorly in respect to the adductor tubercle. Its lower margin was difficult to define. Given the importance of this structure, it must be reconstructed as anatomically as possible in its insertion and in its shape. Many attempts have been made to make functional reconstructions with less than excellent results.

Bilateral medial patellofemoral ligament reconstruction in high-level athletes

This report presents two cases of high-level athletes with bilateral patellar dislocations who were able to return to their preinjury level of activity after bilateral medial patellofemoral ligament (MPFL) reconstruction, without any major complications. Patient 1 was a 19-year-old male volleyball player for a top-level college volleyball team, and patient 2 was a 24-year-old woman who was a member of a national-level adult softball team. MPFL reconstruction could be an effective treatment for bilateral patellar dislocation in high-level athletes. Level of evidence V.

Evaluation of medial patellofemoral ligament tears after acute lateral patellar dislocation: comparison of high-frequency ultrasound and MR

OBJECTIVES

The purpose of this study was to compare the diagnostic performance of high-frequency ultrasound with MR in the evaluation of medial patellofemoral ligament (MPFL) lesions after acute lateral patellar dislocation (LPD).

METHODS

High-frequency ultrasound and MR images were prospectively obtained in 97 consecutive patients with acute LPD. Images were acquired using standardised protocols and were independently evaluated by two radiologists. The MPFL was assessed at three sites (patellar insertion, femoral attachment, and mid-substance) for signs of injury.

RESULTS

Of a total of 291 sites in 97 MPFLs, 127 showed proven MPFL tear at surgery, including 51 sites of complete tear and 76 sites of partial tear. In a site-based analysis, the sensitivity, specificity, and accuracy of high-frequency ultrasound was 90.8%, 96.3%, and 94.6%, respectively, for partial MPFL tear and 86.3%, 96.3%, and 94%, respectively, for complete tear. For MR, the sensitivity, specificity, and accuracy was 81.6%, 95.7%, and 91.3%, respectively, for partial MPFL tear and 80.4%, 95.7%, and 92.1%, respectively, for complete tear. There was no statistical difference between high-frequency ultrasound and MR in the assessment of partial (P = 0.1, 0.777, 0.155) or complete (P = 0.425, 0.777, 0.449) MPFL lesions. Interobserver agreement was very good for high-frequency ultrasound and good for MR.

CONCLUSIONS

Data suggest that high-frequency ultrasound and MR have similar diagnostic performance in the evaluation of MPFL lesions after acute LPD.

KEY POINTS

• High-frequency ultrasound and MR were able to detect MPFL lesions after acute lateral patellar dislocation. • High-frequency ultrasound and MR showed similarly high accuracy in diagnosing MPFL lesions. • Interobserver agreement was very good for high-frequency ultrasound and good for MR.

Surgical versus non-surgical management for primary patellar dislocations: an up-to-date meta-analysis

The aim of this up-to-date meta-analysis was to compare the effects of surgical versus non-surgical treatment of patients following primary patellar dislocation and to provide the best evidence currently available. A comprehensive literature search was conducted using multiple databases, including Medline, Embase, and Cochrane Registry of Clinical Trials. All databases were searched from the earliest records to May 2013. Eligible studies were selected, and data were extracted by two independent investigators. The primary outcome variable was the frequency of recurrent patellar dislocation. The other outcomes included knee function scores, patient-rated outcomes, and radiographic examination. If appropriate, meta-analysis of these variables was performed. Nine independent trials were found to match the inclusion criteria. The pooled results demonstrated that the incidence of recurrent patellar dislocation and Hughston visual analog scale was significantly lower in the surgical treatment group than that in the non-surgical treatment group (P < 0.05). There was no statistically significant difference between the two treatment groups in frequency of subsequent surgical interventions, percentage of excellent or good subjective opinion, Kujala score, pain score on visual analog scale, and severity of patellofemoral joint osteoarthrosis (P > 0.05). This up-to-date meta-analysis indicates that surgical treatment was associated with a lower risk of recurrent patellar dislocation, but a lower Hughston VAS than non-surgical treatment for primary patellar dislocation. More large high-quality trials and further studies are needed to overcome the limitations of small sample sizes, and varieties of different surgical procedures or non-surgical management strategies adopted in the included trials.