First-time Patellar Dislocation Research Articles

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

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. 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 2cm 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. 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%). 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. 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.

Epidemiology of Lateral Patellar Dislocation Including Bone Bruise Incidence: Five Years of Data from a Trauma Center.

Systematic summary of the epidemiology of patellar dislocation is rare. This study aims to investigate sex-, age-, type-, injury causing events-, incidence of bone bruise and time from last injury (TFLI)-specific characteristics, and detail the epidemiological characteristics of patellar dislocation. In this descriptive epidemiological study, a total of 743 patients who have a history of lateral patellar dislocation with either first-time patellar dislocation (FPD) or recurrent patellar dislocation (RPD) between August 2017 and June 2022 at our institution met the inclusion criteria and were selected in this study. Patient characteristics including the type, gender, age, events leading to patellar dislocation, incidence of patellar bone bruise, and the time from last injury (TFLI) of patellar dislocation were retrospectively obtained and described. Magnetic resonance imaging scans (MRI) of the knee were reviewed for insuring bone bruise. Among the 743 patients with patellar dislocation who required surgical reconstruction of the medial retinaculum, 418 (56.2%) had RPD and 325 (43.8%) had FPD. There were more females (65.0%) than males (35.0%) in patellar dislocation patients. Among the female patients, those aged <18 years had higher incidence (31.4%) of patellar dislocation. Among the male patients, those aged <18 and 19-28 years had higher incidence (16.8%) of patellar dislocation. Of all age groups, the prevalence rate of patellar dislocationwas high in juvenile population and females, but with no statistical significance. The most common patellar dislocation-causing event was sport accidents (40.1%), followed by life accidents (23.2%). The incidence of left-knee patellar dislocation was slightly higher than that of right-knee patellar dislocation. The incidence of patellar bone bruise of RPD (63.2%) was significantly lower (p < 0.05) than that of FPD (82.2%). Patellar dislocation patients with bone bruise had shorter time from last injury (TFLI) than those without patellar bone bruise (p < 0.05). The incidence of bone bruise of RPD was lower than that of FPD, and patients with patellar bone bruise may have a shorter time from last injury than those without bone bruise.

Retracted: Anatomic Risk Factors for Osteochondral Fracture of Acute First-Time Patellar Dislocation in Adolescents: A Retrospective Magnetic Resonance Imaging Study.

[This retracts the article DOI: 10.1155/2022/6723326.].

Poster 137: Influence of Body Mass Index on T1ρ Relaxation Times for Patellofemoral Cartilage: Patellar Dislocation Patients vs. Healthy Controls

Objectives: Patellar dislocations are associated with patellofemoral cartilage degradation following injury and a high risk of patellofemoral post-traumatic osteoarthritis (PTOA). Obesity is also a primary risk factor for patellofemoral cartilage degradation and OA, but the influence of obesity on cartilage degradation follow patellar dislocations is unknown. The current study uses T1ρ-based relaxation time mapping of patellofemoral cartilage to evaluate the influence of body mass index (BMI) on cartilage properties in the acute phase following a patellar dislocation, and compares the results to healthy knees. The hypothesis of the study is increasing BMI is associated with cartilage matrix degeneration for injured and healthy knees. Methods: The IRB-approved study focused on a BMI range from underweight to obese (&lt; 40 kg/m2). The population included 18 patients being treated conservatively for a unilateral, first-time patellar dislocation (20 ± 8 years, 9 females, BMI: 24 ± 5 kg/m2, 56 ± 39 days since dislocation), 12 patients being treated conservatively for multiple unilateral dislocations (19 ± 6 years, 9 females, 24 ± 5 kg/m2, 67 ± 35 days since most recent dislocation), and 16 healthy controls (21 ± 7 years, 7 females; 21 ± 7 kg/m2). MRI scans included a 3D water excitation double echo steady state (DESS) scan of the knee for segmentation of the cartilage surfaces (slice thickness of 0.7 mm) and a T1ρ relaxation time scan (fat saturated scan, slice thickness = 4 mm, spin lock times = 0, 10, 40, and 80 ms, spin-lock frequency = 500 Hz). Long T1ρ relaxation times indicate low proteoglycan concentration within cartilage. Automated algorithms based on machine learning were used to segment cartilage on the patella and within the trochlear groove. Additional automated algorithms mapped T1ρ relaxation times to the reconstructed cartilage surfaces (Fig. 1). Mean T1ρ relaxation times were quantified for patellar and trochlear groove cartilage for each knee. Linear regression were used to correlate T1ρ relaxation times with BMI for the single dislocation, multiple dislocations, and control groups. Statistical significance was set at p &lt; 0.05. Results: Patellofemoral T1ρ relaxation times increased with BMI for healthy control subjects, but decreased with BMI following patellar dislocation. For control subjects, the increase in T1ρ relaxation times with BMI was significant for cartilage on the patella and within the trochlear groove (r2 &gt; 0.4, p &lt; 0.01). For patients being treated for a single dislocation and multiple dislocations, the decrease in T1ρ relaxation times with increasing BMI was significant for cartilage on the patella and within the trochlear groove (r2 &gt; 0.25, p &lt; 0.025 for single dislocations, r2 &gt; 0.3, p &lt; 0.05 for multiple dislocations). Conclusions: The expected increase in T1ρ relaxation times with BMI was observed for healthy control subjects, but not for patients being treated for patellar dislocations. Elevated T1ρ values indicate loss of proteoglycan content that reduces cartilage integrity and could be an initiation point for progression to OA. For cartilage throughout the patellofemoral joint, T1ρ relaxation times decreased as BMI increased following patellar dislocation. The relationships were similar following one dislocation and multiple dislocations. The regression lines for injured knees and controls crossed at a BMI of approximately 25 for patellar and trochlear groove cartilage, indicating T1ρ relaxation times are higher for injured knees than healthy controls only for patients with a BMI &lt; 25 (underweight or healthy weight). Multiple previous studies have identified elevated patellofemoral cartilage relaxation times from quantitative MRI following single and multiple patellar dislocations, but no study has previously attributed the difference to patients with a low BMI. The mechanism by which a high BMI limits cartilage degradation following patellar dislocation is currently unknown. The opposing relationships between T1ρ relaxation times and BMI for injured knees and controls occur despite similar ranges for T1ρ times and BMI. The primary difference between injured knees and controls is the recent dislocation event, and the ensuing inflammatory response. The single and multiple dislocation groups have a recent dislocation and inflammation in common despite differences in time since the first dislocation. Impact injury to cartilage is primarily limited to the medial patella, so is unlikely to cause the difference in trends. Pathologic patellofemoral anatomy is a characteristic of knees with patellar instability that could also influence the relationship with BMI. Additional enrollment and characterization of anatomical factors and inflammatory conditions is needed to identify factors that interact with BMI. Follow up analyses are also needed to determine if these relationships weaken with time from injury.

MPFL Repair Versus Rehabilitation After Acute First-Time Patellar Dislocation: A Systematic Review And Meta-Analysis

MPFL Repair Versus Rehabilitation After Acute First-Time Patellar Dislocation: A Systematic Review And Meta-Analysis

Current understanding of the first-time patellar dislocation

Current understanding of the first-time patellar dislocation

Incidence and concomitant chondral injuries in a consecutive cohort of primary traumatic patellar dislocations examined with sub-acute MRI

PurposeTo present age- and sex-specific cumulative annual incidences of primary traumatic lateral patellar dislocation (LPD) and to detail patient characteristics and concomitant chondral injuries including osteochondral fractures, as visualized on magnetic resonance imaging (MRI), in a large consecutive cohort of knee-injured individuals.MethodsData on primary traumatic lateral patellar dislocations were collected from a large consecutive cohort of knee injuries examined with sub-acute MRI in a single centre with a well-defined catchment area. Annual incidences for different age-groups in relation to gender were calculated together with the risk of concomitant chondral and osteochondral injury, during sports and in general.ResultsA total of 184 primary patellar dislocations were identified in the cohort of 1145 acute knee injuries (n=175) and surgical records (n=9). Knee MRI was performed within a median of six days of injury. Median age of patients with primary LPD was 16 years (interquartile range, 14–21; range, 9–47) and 41% were females. Males were significantly older than females at the time of injury (median age 17 vs. 15, P = 0.021) and sustained their primary LPD during sports more often than females (65 vs. 40%, P < 0.001). Primary LPD occurred most frequently at the age of 13 to 15 years where the annual incidence was 125 (95% CI, 96–160) per 100,000 persons. The overall annual incidence of primary LPD was 14 (95% CI, 12–16) per 100,000 persons, with a predominance of males versus females (17 vs. 11, P = 0.01). Concomitant lesions to joint surfaces were displayed on MRI or during surgery in 75 (43%) knees. Osteochondral fractures were seen in 32 knees (18%). We found no statistically significant difference in the risk of osteochondral fracture between those injured during sports or during leisure activity (14 vs. 24%, P = 0.08).ConclusionsThe annual incidence of first-time patellar dislocation was found to be 14 per 100,000 individuals with the highest incidence found among those aged 13–15 years. Primary LPD was more common among males and was sustained during sports activity in 55% of the cases. Associated injuries to the chondral surfaces should be expected in 43% of knees with primary LPD where 18% represent osteochondral fractures.

Children’s orthopaedics

The February 2023 Children’s orthopaedics Roundup360 looks at: Trends in management of paediatric distal radius buckle fractures; Pelvic osteotomy in patients with previous sacral-alar-iliac fixation; Sacral-alar-iliac fixation in patients with previous pelvic osteotomy; Idiopathic toe walking: an update on natural history, diagnosis, and treatment; A prediction model for treatment decisions in distal radial physeal injuries: a multicentre retrospective study; Angular deformities after percutaneous epiphysiodesis for leg length discrepancy; MRI assessment of anterior coverage is predictive of future radiological coverage; Predictive scoring for recurrent patellar instability after a first-time patellar dislocation.

Lateral Patellar Instability.

Patellar instability represents a common problem with an evolving understanding and multifactorial pathoetiology. Treatment plans should be based on the identification of contributing anatomical factors and tailored to each individual patient. Risks for recurrent instability are dependent on several patient-specific factors including patella alta, increased tibial tubercle-to-trochlear groove (TT-TG) distance, trochlear dysplasia, younger skeletal age, and ligamentous laxity. Cartilage or osteochondral lesions and/or fractures are commonly observed in first-time patellar dislocation, and magnetic resonance imaging (MRI) should be strongly considered. Advanced imaging modalities, such as computed tomography (CT) or MRI, should also be obtained preoperatively to identify predisposing factors and guide surgical treatment. Medial patellofemoral ligament (MPFL) reconstruction with anatomical femoral tunnel positioning is associated with lower recurrence rates compared with MPFL repair and has become a common and successful reconstructive surgical option in cases of instability. Lateral retinacular tightness can be addressed with lateral retinacular release or lengthening, but these procedures should not be performed in isolation. Tibial tubercle osteotomy is a powerful reconstructive tool in the setting of underlying skeletal risk factors for instability and can be of particular benefit in the presence of increased TT-TG distance (>20 mm), and/or in the setting of patella alta. The indications for trochleoplasty are still developing along with the clinical evidence, but trochleoplasty may be indicated in some cases of severe trochlear dysplasia. Several surgical techniques have indications in specific clinical scenarios and populations, and indications, risks, and benefits to each are progressing with our understanding. Combined femoral derotational osteotomy and MPFL reconstruction can be considered for patients with a femoral anteversion angle of >30° to improve patient outcomes and reduce recurrence rates.

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

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. 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). 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 35years 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 > 20mm (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. 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 15days and up to 60° for an additional 15days. 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. IV.

MPFL repair after acute first-time patellar dislocation results in lower redislocation rates and less knee pain compared to rehabilitation: a systematic review and meta-analysis.

This study aimed to explore the efficacy of medial patellofemoral ligament (MPFL) repair versus nonoperative rehabilitation treatment on the rate of patellar redislocation and functional outcomes in skeletally mature patients with traumatic, first-time patellar dislocations. MEDLINE, PubMed and EMBASE were searched from database inception to May 2022 for studies examining the management options for acute first-time patellar dislocations. This study was conducted in accordance with PRISMA and R-AMSTAR guidelines. Data on redislocation rates, functional outcomes including the Kujala score for anterior knee pain,and complication rates were extracted. A meta-analysis was used to pool the mean postoperative Kujala score and calculate the proportion of patients sustaining redislocations using a random effects model. Quality assessment of included studies was performed for all included studies using the MINORS and Detsky scores. This review included a total of 25 studies and 1,361 patients.The pooled mean redislocation rate in 15 studies comprising 798 patients in the rehabilitation group was 30% (95% CI 25-36%, I2 = 65%). Moreover, the pooled mean redislocation rate in 10studies comprising 170 patients undergoing MPFL repair was 7% (95% CI 3-12%, I2 = 30%).The pooled mean postoperative Kujala score in 8 studies comprising 396 patients in the rehabilitation group was 82.5 (95% CI 78.3-86.8, I2 = 91%), compared to a score of 88 (95% CI 87-90, I2 = 76%) in 3 studies comprising 94 patients in the repair group. Range of motion deficits was reported in 3.8% of 893 patients in the rehabilitation group and 2.0% of 205 patients in the repair group. MPFL repair resulted in a lower rate of redislocation, less knee pain, and noninferiority with respect to a range of motion deficits compared to nonoperative treatment for the management of acute first-time patellar dislocations. IV.

Medial Patellofemoral Ligament Reconstruction is Preferred to Repair or Reefing for First-Time Patellar Dislocation: A Systematic Review and Meta-analysis.

The purpose of this systematic review aimed to investigate the clinical outcome of medial patellofemoral ligament (MPFL) reconstruction, MPFL repair and medial reefing for patients with first-time patellar dislocation. Databases of PubMed, EMBASE, Cochrane Library and Web of Science were searched up to May 8, 2022. Only articles treating first-time patellar dislocation with MPFL reconstruction, MPFL repair and medial reefing were included in the analysis. Eligible identification, data extraction, quality assessment and statistical analysis were performed by two independent reviewers. The primary outcome measures were the incidences of postoperatively redislocation and reoperation. The second outcomes were the Kujala functional score and complications (including infection, osteoarthritis, and loss of range of motion). Twenty-two studies involving 668 patients met the inclusion criteria. Of which, four studies involving 126 patients were in MPFL reconstruction group, ten studies involving 220 patients in MPFL repair group and 9 studies involving 322 patients in medial reefing group. Our results showed that the MPFL reconstruction (1.8%, 95% CI -0.5 to 4.0%) had a significantly lower rate of postoperative redislocation and reoperation rate than the MPFL repair (15.4%, 95% CI 5.2-25.7%) and medial reefing (18.0%, 95% CI 9.3-26.7%). Besides, no significant differences were found in the Kujala score and complication rate among the three treatments. The available evidence demonstrated that MPFL reconstruction could achieve significantly lower redislocation rate and reoperation rate than MPFL repair and medial reefing after first-time patella dislocation. Furthermore, there was not enough evidence to reveal that MPFL reconstruction provided better functional outcome compared with MPFL repair and medial reefing. MPFL reconstruction is a preferred surgical treatment for patients with first-time patellar dislocation. Level IV, systematic review of Level I-IV.

The incidence of musculoskeletal injuries: a systematic review and meta-analysis.

The aim of this systematic review and meta-analysis was to gather epidemiological information on selected musculoskeletal injuries and to provide pooled injury-specific incidence rates. PubMed (National Library of Medicine) and Scopus (Elsevier) databases were searched. Articles were eligible for inclusion if they reported incidence rate (or count with population at risk), contained data on adult population, and were written in English language. The number of cases and population at risk were collected, and the pooled incidence rates (per 100,000 person-years) with 95% confidence intervals (CIs) were calculated by using either a fixed or random effects model. The screening of titles yielded 206 articles eligible for inclusion in the study. Of these, 173 (84%) articles provided sufficient information to be included in the pooled incidence rates. Incidences of fractures were investigated in 154 studies, and the most common fractures in the whole adult population based on the pooled incidence rates were distal radius fractures (212.0, 95% CI 178.1 to 252.4 per 100,000 person-years), finger fractures (117.1, 95% CI 105.3 to 130.2 per 100,000 person-years), and hip fractures (112.9, 95% CI 82.2 to 154.9 per 100,000 person-years). The most common sprains and dislocations were ankle sprains (429.4, 95% CI 243.0 to 759.0 per 100,000 person-years) and first-time patellar dislocations (32.8, 95% CI 21.6 to 49.7 per 100,000 person-years). The most common injuries were anterior cruciate ligament (17.5, 95% CI 6.0 to 50.2 per 100,000 person-years) and Achilles (13.7, 95% CI 9.6 to 19.5 per 100,000 person-years) ruptures. The presented pooled incidence estimates serve as important references in assessing the global economic and social burden of musculoskeletal injuries.Cite this article: Bone Joint Res2022;11(11):814-825.

Anatomic Risk Factors for Osteochondral Fracture of Acute First-Time Patellar Dislocation in Adolescents: A Retrospective Magnetic Resonance Imaging Study.

Objective To analyze the risk factors for osteochondral fracture (OCF) of first-time acute patellar dislocation (APD) through measurements of patellofemoral anatomy in adolescents. Methods In this prospective study, all patients were divided into two groups according to whether OCF was detected on magnetic resonance imaging (MRI): Group A (associated with OCF) and Group B (without OCF). Patellofemoral anatomy was evaluated with four aspects including trochlear/patellar dysplasia, patella location, patellofemoral matching, and morphologic classification. On MRI scans, trochlear facet asymmetry ratio (TFAR), lateral trochlear inclination (LTI), sulcus angle (SA), trochlear depth (TD), and patellar depth (PD) were measured to assess trochlear/patellar dysplasia. Insall–Salvati index (ISI), Caton–Deschamps index (CDI), Blackburne–Peel index (BPI), lateral patellofemoral angle (LPFA), patellar tilt angle (PTA), and lateral patellar displacement (LPD) were measured to show the location of patella. Patellofemoral matching was analyzed through the measurements of patellofemoral congruence angle (PFCA), patellofemoral index (PFI), and patellotrochlear index (PTI). Results A total of ninety-four adolescents from 49 boys and 45 girls (mean age, 15 years; range, 10–18 years) with first-time APD were recruited and included in Group A (65) and Group B (29). The PFI (2.62 ± 0.51 vs. 2.10 ± 0.44) and PTI (0.28 ± 0.05 vs. 0.22 ± 0.07) were significantly higher in Group B than Group A (P < 0.05). There were no significant differences in other quantitative outcomes of the two groups (P > 0.05). The distribution of Dejour/Wiberg classification was statistically similar between the two groups (P > 0.05). Conclusions Adolescent patients with first-time APD complicating OCF have closer morphologic features of patellofemoral dysplasia and patella location when compared to adolescents without OCF. Abnormal patellofemoral matching increases the risk of OCF after first-time APD in adolescents.

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

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. 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. 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. 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.

MPFL reconstruction results in lower redislocation rates and higher functional outcomes than rehabilitation: a systematic review and meta-analysis.

To determine the effect of early MPFL reconstruction versus rehabilitation on the rate of recurrent patellar dislocations and functional outcomes in skeletally mature patients with traumatic, first-time patellar dislocation. Three online databases MEDLINE, PubMed and EMBASE were searched from database inception (1946, 1966, and 1974, respectively) to August 20th, 2021 for literature addressing the management of patients sustaining acute first-time patellar dislocations. Data on redislocation rates, functional outcomes using the Kujala score, and complication rates were recorded. A meta-analysis was used to pool the mean postoperative Kujala score, as well as calculate the proportion of patients sustaining redislocation episodes using a random effects model. Quality assessment of included studies was performed for all included studies using the MINORS and Detsky scores. A total of 19 studies and 1,165 patients were included in this review. The pooled mean redislocation rate in 14 studies comprising 734 patients in the rehabilitation group was 30% (95% CI 25-36%, I2 = 67%). Moreover, the pooled mean redislocation rate in 5 studies comprising 318 patients undergoing early MPFL reconstruction was 7% (95% CI 2-17%, I2 = 70%). The pooled mean postoperative Kujala anterior knee pain score in 7 studies comprising 332 patients in the rehabilitation group was 81 (95% CI 78-85, I2 = 78%), compared to a score of 87 (95% CI 85-89, I2 = 0%, Fig.4) in 3 studies comprising 54 patients in the reconstruction group. Management of acute first-time patellar dislocations with MPFL reconstruction resulted in a lower rate of redislocation of 7% in the reconstruction group vs 30% in the rehabilitation group and a higher Kujala score compared to the rehabilitation group. The information this review provides will help surgeons guide their decision to choose early MPFL reconstruction versus rehabilitation when treating patients with first-time patellar dislocations and may guide future studies on the topic. IV.

Elevated Patellofemoral and Tibiofemoral T1ρ Relaxation Times Following a First Time Patellar Dislocation.

ObjectiveThe study was performed to evaluate cartilage within the knee following a first-time patellar dislocation, using elevated MRI-based T1ρ relaxation times as an indicator of low proteoglycan concentration. The hypothesis is that MRI-based T1ρ relaxation times for patellofemoral and tibiofemoral cartilage are significantly longer for knees being treated for patellar dislocation than for healthy control knees.DesignTwenty-one subjects being treated for a first-time, unilateral dislocation of the patella and 16 healthy controls participated in MRI-based T1ρ relaxation time mapping. Mean relaxation times were quantified for patellofemoral and tibiofemoral regions for injured knees, the contralateral knees, and healthy controls. T1ρ values for each region were compared between the 3 groups with generalized estimating equations. Linear regressions were also performed to correlate T1ρ relaxation times with time from injury.ResultsThe knees with a disloction had longer T1ρ relaxation times than the contralateral knees and control group at the medial patella and longer relaxation times than the control group at the lateral tibia (P < 0.05). T1ρ relaxation times at the medial patella also decreased with time from injury (r2 = 0.21, P = 0.037).ConclusionsCompositional changes to cartilage on the medial patella are related to traumatic impact during a dislocation. Potential exists for cartilage properties at the medial patella to improve with time. Cartilage degradation at the lateral tibia is not directly related to traumatic impact. The current baseline data are a starting point to characterize the pathway from a first-time dislocation to progressive cartilage degradation and osteoarthritis.

Risk assessment and management of primary patellar dislocation is complex and multifactorial: a survey of Australian knee surgeons

ObjectivesRecurrent patellar instability following first-time lateral patellar dislocation is associated with a variety of bony, soft tissue and patient-related risk factors. The specific management of recurrent dislocation may vary depending on the presence and combination of these factors as well as the treating physician’s interpretation of these. Therefore, this study aimed to determine which factors Australian knee surgeons regard as increasing the risk of recurrence following first-time patellar dislocation and to characterise the surgical decision-making process of these surgeons in the management of lateral patellar instability.MethodsAn online survey was sent to all active members of the Australian Knee Society (AKS). The survey addressed (i) risk factors for recurrence following first-time patellar dislocation and (ii) the surgical decision-making process in treating patellar instability.ResultsSeventy-seven per cent (53 of 69) Australian Knee Society members responded. Factors identified by respondents as significantly increasing the risk of recurrence were a history of contralateral recurrent patellar dislocation (74% respondents), an atraumatic injury mechanism (57%), trochlear dysplasia (49%) younger age (45%), patella alta (43%) and generalised ligamentous laxity (42%). Forty-four per cent replied that there may be an indication for surgical intervention following first-time patellar dislocation with no apparent loose body present. All respondents would recommend operative management of recurrent patellar dislocation after a third episode, with 45% of surgeons recommending surgery after a second episode. The most common surgical procedures performed by respondents were medial patellofemoral ligament (MPFL) reconstruction (94%), tibial tuberosity medialisation (91%) and tibial tuberosity distalisation (85%). Only 23% of respondents consider trochleoplasty for primary surgical intervention.ConclusionSurgeons identified a large number of factors that they use to assess risk of recurrence following first-time patellar dislocation, many of which are not supported by the literature. The two highest ranked factors (history of contralateral recurrent patellar dislocation and an atraumatic injury mechanism) are without a significant evidence base. There was considerable variation in the criteria used to make the decision to perform a patellar stabilisation procedure. MPFL reconstruction was the most commonly used procedure, either in isolation or combined with another procedure.Level of evidenceCross-sectional study; expert opinion (Level V).

MANAGEMENT OF FIRST-TIME PATELLAR DISLOCATION: A SURVEY OF PRISM MEMBERS (201)

Objectives:There are no current guidelines for optimal management of first-time patellar dislocation in children and adolescents. The objective of this study was to develop consensus-based guidelines for management of first-time dislocation in adolescents.Methods:A 29-question, case-based, multiple-choice survey was developed after 2-rounds of iterations by 20 members of the Patellofemoral RIG. The survey contained two case scenarios of first-time patellar dislocation in adolescents - one with and one without an osteochondral fracture. The survey was administered to primary sports medicine and orthopedic surgeons of the PRISM Society in April 2020 and the responses were analyzed. Consensus-based guidelines were generated when at least 66% of the respondents agreed.Results:81/276 (29%) members responded to the survey and 6 consensus-based guidelines were generated from those responses (Table 1).There was no consensus between conservative (60%) and operative (40%) treatment of contralateral patellar dislocation. Free-text analysis revealed several variables that influence the decision-making process.Conclusions:There are changes in trends related to management of first-time dislocation in adolescents. MRI, though not recommended for all patients with first-time dislocation, was obtained by 51% of respondents. The survey provides details of conservative treatment, including the role and duration of bracing and physical therapy. For first-time dislocation with an osteochondral fracture, concomitant patellar stabilization is preferred over isolated fixation. Simultaneous guided-growth for genu valgum correction is recommended. There were several variables that influenced the decision-making process and there were several areas of discordance. Further research studies on these parameters could potentially improve outcomes. *PF RIG members: Matthew Ellington, MD, Craig J Finlayson, MD, Joseph Molony, Jr., PT, MS, SCS, CSCS, Nicole Friel, MD MS, Daniel W Green, MD, Jeffery L Mikutis, DO, Todd A Milbrandt, MD, James L Pace, MD, Albert M Pendleton, MD, Lauren H Redler, MD, Jason Rhodes, MD, Shannon D Safier, MD, John A Schlechter, MD, Beth E Shubin Stein, MD, Curtis Vandenberg, MD, Jeffrey M Vaughn, DO, Eric J Wall, MD, Drew E Warnick, MD, Moshe Yaniv, MD, Shital N Parikh, MD.

Assessment of knee flexor muscles strength in patients with patellar instability and its clinical implications for the non-surgical treatment of patients after first patellar dislocation - pilot study

BackgroundBiomechanical studies indicate that during outward rotation of the tibia and the valgus knee joint position, the patella is shifted in the lateral direction. After first-time patellar dislocation, the dynamic position of the femur in relation to the tibia plays an important role in joint stability, because the medial stabilizer of the patella (mostly the MPFL) is damaged or inefficient. The most important factor in controlling the rotational movement of the tibia in relation to the thigh are the hamstring muscles. The aim of the study therefore is to determine whether patients with patellar instability have a significant weakness in the knee flexor muscles, which can predispose to recurrent dislocations. This is an important consideration when planning the rehabilitation of patients with first-time patellar dislocation.MethodsThe study enrolled 33 patients with confirmed recurrent patellar dislocation, including six patients with bilateral involvement. In the study group, the hamstring muscles (both sides) were evaluated at velocities of 60 and 180 deg/s for the following parameters: peak torque, torque at 30 degrees of knee flexion, angle of peak torque and peak torque hamstring to quadriceps ratio (H/Q ratio).ResultsIn the recurrent patellar dislocation group, a statistically significant weakness in knee flexors was observed for both angular velocities compared to age and gender normative data. No such relationship was observed in the control group of heathy subjects. In patients with one-sided dislocation, no differences were found in knee flexors peak torque, torque at 30 degrees of knee flexion, angle of peak torque or H/Q ratio between the healthy and affected limbs for either angular velocity.ConclusionsIn patients with recurrent patellar dislocation, knee flexors strength is decreased significantly in both the unaffected and affected limbs. This may indicate a constitutional weakening of these muscles which can predispose to recurrent dislocations.Trial registrationThe study was retrospectively registered on ClinicalTrials.gov (NCT04838158), date of registration; 22/03/2021.