Recurrent Lateral Patellar Dislocation Research Articles

The Importance of Medial Patellar Shape as a Risk Factor for Recurrent Patellar Dislocation in Adults

Background: Research on the cause of lateral patellar dislocation (LPD) has focused on trochlear morphologic parameters, joint alignment, and patellofemoral soft tissue forces. A paucity of information is available regarding how patellar morphologic parameters influence the risk for LPD. Purpose/Hypothesis: The purpose was to assess whether patellar morphology is a risk factor for recurrent LPD. It was hypothesized that (1) patients with recurrent LPD would have decreased patellar width and volume and (2) patellar morphologic parameters would accurately discriminate patients with recurrent LPD from controls. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A total of 21 adults with recurrent LPD (age, 29.7 ± 11.1 years; height, 170.8 ± 9.9 cm; weight, 76.1 ± 17.5 kg; 57% female) were compared with 21 sex- and height-matched controls (age, 27.2 ± 6.7 years; height, 172.0 ± 10.6 cm; weight, 71.1 ± 12.8 kg; 57% female). Three-dimensional axial fat-saturated magnetic resonance imaging scans were used to measure patellar medial, lateral, and total width; patellar volume; patellar medial and lateral facet length; the Wiberg index; and previously validated knee joint alignment and femoral shape measurements (eg, tibial tuberosity to trochlear groove distance, trochlear dysplasia). Results: The LPD group demonstrated reduced medial patellar width (Δ = −3.6 mm; P < .001) and medial facet length (Δ = −3.7 mm; P < .001) but no change in lateral width or facet length. This resulted in decreased total patellar width (Δ = −3.2 mm; P = .009), decreased patellar volume (Δ = −0.3 cm3; P = .025), and an increased Wiberg index (Δ = 0.05; P < .001). No significant differences were found for all other patellar shape measures between cohorts. Medial patellar width was the strongest single discriminator (83.3% accuracy) for recurrent LPD. Combining medial patellar width, patellofemoral tilt, and trochlear groove length increased the discrimination to 92.9%. Conclusion: The medial patellar width was significantly smaller in patients with recurrent LPD and was the single most accurate discriminator for recurrent LPD, even compared with traditional trochlear shape and joint alignment measures (eg, trochlear dysplasia, patella alta). Therefore, medial patellar morphology should be assessed in patients with LPD as a risk factor for recurrence and a potential means to improve treatment.

Medial Patellofemoral Ligament and Lateral Patellofemoral Ligament Reconstruction after Tibial Tuberosity Transposition in a Young Woman with Patellar Instability

In patients with reccurent lateral and medial patellar instability, isolated medial patellofemoral ligament (MPFL) reconstruction may be insufficient due to poor lateral retinacular tissue quality. In this report, we describe a case of a patient that underwent simultaneous MPFL and lateral patellofemoral ligament (LPFL) reconstruction on the left knee due to chronic bidirectional patellar instability. A 29-year-old female patient presented with first-time lateral patellar dislocation five years ago due to acute strain. She underwent a tibial tuberosity transposition in another hospital. After the surgery, she suffered from recurrent medial and lateral patellar dislocation and presented to our center. MPFL and concomitant LPFL reconstruction on the left knee was simultaneously performed due to bilateral patellar dislocation. The patella was stable postoperatively, and the patient underwent physiotherapy with successful results to date. Single-time patellar dislocation should be treated conservatively. Surgical treatment after the first episode of dislocation can magnitude the risk of postoperative complications. The simultaneous reconstructing of the LPFL yields patellar fixation indistinguishable from the native LPFL. These grafts provide separate tensioning depending on body anatomy, allowing for individualized stability. Anatomical MPFL reconstruction is supported by well-established high-quality research. Reconstructing the LPFL anatomically yields patellar fixation indistinguishable from the native LPFL.

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

BackgroundRecurrent lateral patellar dislocation (RLPD) poses a significant threat to patients’ quality of life due to knee pain, patellofemoral cartilage damage, and potential traumatic arthritis. Predictive scoring systems have been developed to assess the risk of RLPD; however, their relative accuracy remains uncertain.PurposeTo investigate the accuracy of the multiple regression models to predict the individual risk of recurrent LPD.MethodsThe Patellar Instability probability calculator (PIP), Recurrent Instability of the Patella Score (RIP), and Patellar Instability Severity Score (PIS) scoring rules were measured in 171 patients with a history of patellar dislocation and 171 healthy individuals. Three prediction models were calculated based on the data to predict the risk of recurrent lateral patellar dislocation. The inter-observer and intra-observer reliability of each measurement parameter was evaluated. The predictive capacity of the three-prediction model was investigated using the receiver operating characteristic curve.ResultsIn the case group of 171 patients, PIS accurately predicted recurrent lateral Patella dislocation in 143 patients. RIP was 96, and PIP was 83. The positive predictive values were 92.9%, 64%, and 68% respectively. In the control group of 171 patients, the PIS was validated in 160 patients who would not experience dislocations. RIP was 117, and PIP was 50. The negative predictive values were 85.1%, 60.9%, and 36.2%, respectively. The area under the curve score for the PIS was 0.866, and the RIP was 0.673. the PIP was 0.678.ConclusionRIP and PIP did not work to predict LPD. PIS can accurately predict recurrent lateral patellar dislocation. It can aid doctors in making treatment decisions.Level of evidenceLevel III, retrospective comparative study.

Association between single leg hop tests and patient reported outcome measures and patellar instability in patients with recurrent patellar dislocations

ObjectivesTo assess the associations between the single leg hop tests at two premises; baseline and the change after 12 months, and change in patient reported outcome measures and persistent instability...

Lateral trochlear inclination measured by the transepicondylar axis holds potential for evaluating trochlear dysplasia in patients with lateral patellar dislocation.

To verify that lateral trochlear inclination (LTI) measured by the transepicondylar axis can reliably be used to evaluate trochlear dysplasia (TD) on MRI and can serve as an objective indication of trochleoplasty for patients with lateral patellar dislocation (LPD). Eighty patients with recurrent LPD and eighty healthy subjects were included. TD, posterior condylar angle (PCA), and LTI measured by the posterior condylar reference line (LTIp), surgical transepicondylar axis (LTIs), and anatomical transepicondylar axis (LTIa) were assessed on MRI. The intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed, the correlations and differences amongst the parameters were identified, and a binary logistic regression model was established. Each measurement had excellent inter- and intra-observer agreement. The LTIp, LTIs and LTIa were smaller in the study group than in the control group, with mean differences of 9.0°, 7.2° and 7.0°, respectively (P < 0.001). The PCA was larger in patients with LPD than in the control group (P < 0.001). LTIp was associated with PCA in the study group (r = -0.41, P < 0.001). The pathological values of LTIp, LTIs and LTIa were 11.7°, 15.3° and 17.4°, respectively. LTIs and LTIa were independent risk factors for LPD, with ORs of 7.33 (95% CI [1.06-52.90], P = 0.048) and 10.29 (95% CI [1.38-76.96], P = 0.023), respectively. The LTI can be reliably measured by MRI, but LTIp could potentially decrease the recorded value from the actual inclination angle. LTIs and LTIa are more appropriate to serve as trochleoplasty indications for patients with LPD, which could help orthopedists with surgical decision-making. Level III.

Soft Tissue Lengthening for Flexion Dislocation of Patella.

Obligatory dislocation of the patella (also known as habitual dislocation) is a rare subset of patellofemoral instability in which the patella dislocates every time the knee is flexed. The problem arises due to contracture of the quadriceps muscles. Soft tissue lengthening procedures such as quadriceps tendon lengthening are the mainstay of treatment, in contrast to medial patellofemoral reconstruction (MPFL-R) for the more common recurrent lateral patellar dislocation. The current review explores the existing literature surrounding the pathophysiology and treatment strategies for this unique cause of knee instability. Flexion dislocation of the knee often presents in children when they begin to walk. It is also termed obligatory or habitual because the patella dislocates laterally with each flexion and extension cycle of the knee. In contrast to other forms of patellar dislocation, the displacement is painless in obligatory dislocation. Likewise, the underlying biomechanical cause of this issue is related to contracture of tissues lateral to the patella rather than disruption of medial soft tissues as seen in recurrent/traumatic dislocation or subluxation of the patella. A number of procedures have been described for management of obligatory dislocation of the patella, with the general consensus that a combination of procedures including release/lengthening of the proximal lateral soft tissues as a critical component for a successful outcome. Soft tissue release/lengthening has been performed for over 50years to treat obligatory dislocation of the patella. This procedure must be used in combination with other proximal and distal reconstructive with careful intraoperative assessment of knee flexion and patellar tracking for satisfactory outcomes. Further research using standardized outcome measures is needed to identify the optimal step-wise approach in treatment of obligatory patellar dislocation.

Medial Patellofemoral Ligament Reconstruction Using Allografts in Skeletally Immature Patients

Background: Patellar instability has the highest incidence in adolescents aged between 14 and 18 years. The unique relationship between the medial patellofemoral ligament (MPFL) and the distal femoral physis in skeletally immature patients warrants precisely positioned MPFL graft insertion. A paucity of data are available evaluating the results of MPFL reconstruction using allograft tendon before skeletal maturity. Purposes: (1) To assess the results of MPFL reconstruction using allograft tendon in skeletally immature patients by analyzing redislocation and reoperation rates, radiological outcomes, and patient-reported outcomes and (2) to determine whether epidemiological, intraoperative, or radiographic factors influence recurrent instability and clinical outcomes. Study Design: Case series; Level of evidence, 4. Methods: Prospectively collected data were retrospectively analyzed for 69 skeletally immature patients who experienced a first-time or recurrent lateral patellar dislocation and were treated with anatomic MPFL reconstruction. Inclusion criteria were MPFL reconstruction using allograft and the availability of preoperative magnetic resonance imaging scans in the presence of open or partially open physes. Patients with <2 years of follow-up and patients with previous surgeries on the same knee were excluded from the study. Preoperative radiographic imaging was reviewed and analyzed. Trochlear dysplasia, tibial tubercle–trochlear groove distance, and patellar height were evaluated. Descriptive data, concomitant injuries, surgical procedure details, complications, and postoperative history were assessed via review of medical records and patient charts. Validated patient-reported and surgeon-measured outcomes were collected pre- and postoperatively, including Kujala score, Lysholm score, and Tegner activity score. Return-to-sports rate was assessed. The influence of epidemiological, intraoperative, and radiographic parameters on the redislocation rates and clinical outcomes was assessed using a multiple linear regression model. Results: A total of 79 physeal-sparing MPFL reconstructions (69 patients) met the inclusion criteria. The mean age of the patient cohort was 14.7 ± 1.8 years (range, 8.5-16.9 years). Within the mean follow-up time of 37.9 ± 12.1 months (range, 24-85 months after surgery, there were 12 patients with clinical failures resulting in reoperation. Eleven patients experienced a redislocation of the patella, and 1 patient sustained a transverse noncontact patellar fracture 6 months after index surgery that required operative fixation. No injuries to the distal femoral physes were clinically observed. At the final follow-up, patients had a mean Lysholm score (1-100) of 96.5 ± 6.7, a mean Kujala score (1-100) of 96.5 ± 7.4, and a mean Tegner Activity Scale score (1-10) of 4.9 ± 1.3. Patellar height and trochlear dysplasia did not influence redislocation or clinical scores. In total, 57 of the 63 patients (90.5%) who were engaged in sports before injury returned to the same or higher level of competition. In a subgroup analysis of patients who underwent isolated MPFL reconstruction (n = 44) without concomitant procedures, 9 patients (20.5%) experienced failure and had a redislocation. A univariate analysis of hazards for failure based on patient-specific variables was carried out. A body mass index ≥30 conveyed a hazard ratio of 2.51 (95% CI, 0.63-10.1; P = .19), and the tibial tubercle-trochlear groove distance by increments of 1 mm was associated with a hazard ratio of 2.02 (95% CI, 0.51-8.11; P = .32). Conclusion: Physeal-sparing anatomic reconstruction of the MPFL using an allograft tendon in skeletally immature patients was a safe and effective treatment for patellar instability, regardless of patellar height and trochlear dysplasia. Failure rates decreased when the MPFL reconstruction was performed concomitantly with a tibial tubercle osteotomy.

Surgical versus non-surgical interventions for treating patellar dislocation.

Surgical versus non-surgical interventions for treating patellar dislocation.

Isolated Medial Patellofemoral Ligament Reconstruction for the Treatment of Recurrent Lateral Patellar Dislocations: A Systematic Review and Meta-Analysis

Introduction: Being one of the most common acute knee disorders In children and adolescents, the incidence of patellar dislocations among pediatric patients is estimated to 43 per 100,000 with peak of age at 15 years.1 Briefly, a nonoperative treatment have been considered as the standard of care for patellar dislocations.5 However, recurrent patellar instability, osteochondral fractures with loose bodies, and failed non operative measures of functional rehabilitation benefitted from surgical treatment.6 As for the purpose of return-to-sports after surgery, clinicians have been using the utilization of time, ROM, strength, and subjective measures as guidelines.2,10 Methods: The population size was harvested from each study as well as means/medians and ranges for population age and follow-up time. Recurrent instability were taken to note, preoperative and postoperative Tegner for estimated return to play, positive apprehension test and Kujala scores were extracted. he study calculate means for population size, age, postoperative Tegner scores. Results: The total mean population size of all 6 studies was 217 participants, with a mean age and follow-up of 23.5 years and 30.8 months, respectively. The data extracted from all studies included in the review, as well as all calculated means, are presented in Table 3. The total mean population size of all 6 studies was 217 participants, with a mean age and follow-up of 23.5 years and 30.8 months, respectively. Conclusion: The mean postoperative Tegner score was 5.7, calculated from 4 studies. Preinjury and preoperative Tegner scores were reported in only one study. The pooled proportion of athletes who returned to sports after surgery was 84.1% (95% CI, 71.1%– 97.1%) (Figure 1). The pooled estimated mean from 7 studies that reported means ± SDs for the postoperative Kujala score was 85.8 (95% CI, 81.6–90.0; I2 = 92%) (Figure 2). Also, 4 studies reported the frequency at which patients exhibited a positive apprehension sign during follow-up; the pooled risk from these studies was 3.6% (95% CI, 0%–7.2%) (Figure 3). The pooled total risk of recurrent instability after surgery was 1.2% (95% CI, 0.3%–2.1%; I2 = 0%)

Medial Patellofemoral Ligament Reconstruction

Background: Recurrentlateral patellar dislocation is a devastating condition associated with different pathologies, including medial patellofemoral ligament (MPFL) injury, increased tibial tubercle to trochlear groove (TT-TG) distance, and trochlear dysplasia. This video aims to provide an overview of isolated MPFL reconstruction in a patient with recurrent patellar dislocation and chronic MPFL injury. Indications: Isolated MPFL reconstruction is indicated for patients with recurrent lateral patellar instability following an initial trial of nonoperative management, in the absence of other contributing anatomic factors. Candidates for isolated MPFL reconstruction should have a TT-TG distance of &lt;20 mm, and normal or Dejour type A trochlear morphology. Technique Description: Semitendinosus allograft is used to reconstruct the torn or attenuated MPFL. Following diagnostic arthroscopy, an incision is made over the medial border of the patella and dissection is carried through the skin and subcutaneous tissue to the fascia. Two K-wires are over-drilled and two 3.5-mm Arthrex SwiveLock anchors are placed. The allograft is prepared and whipstitched on both sides. The central portion of the graft is tide down to the anchors. A second incision is then made on the medial side of the knee over the epicondyle. Dissection is carried down to the fascia, and palpation is used to identify Schottles’ point. This is confirmed with fluoroscopy. An 8-mm drill bit is then used to drill to a depth of 60 mm on the femoral side. The grafts are passed one at a time through the femoral tunnel. The femoral side is fixed with an Arthrex BioComposite Interference Screw and the incisions are subsequently irrigated and closed in a layered fashion. Results: MPFL reconstruction demonstrates good functional and clinical outcomes with high rates of patient satisfaction and low rates of failure. A recent systematic review demonstrated an 84% rate of return to sport, improved postoperative outcomes, and pooled risks of recurrent instability and reoperation of less than 5% following isolated MPFL reconstruction. Conclusion: Isolated MPFL reconstruction should be considered for patients with recurrent patellar instability in the absence of other clinical risk factors. The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Anatomical Components Associated With Increased Tibial Tuberosity-Trochlear Groove Distance.

Background:Increased tibial tuberosity–trochlear groove (TT-TG) distance is an important indicator of medial tibial tubercle transfer in the surgical management of lateral patellar dislocation (LPD). Changes to TT-TG distance are determined by a combination of several anatomical factors.Purpose:To (1) determine the anatomical components related to increased TT-TG distance and (2) quantify the contribution of each to identify the most prominent component.Study Design:Case-control study; Level of evidence, 3.Methods:Included were 80 patients with recurrent LPD and 80 age- and body mass index–matched controls. The 2 groups were compared in TT-TG distance and its related anatomical components: tibial tubercle lateralization (TTL), trochlear groove medialization, femoral anteversion, tibiofemoral rotation (TFR), tibial torsion, and mechanical axis deviation (MAD). The Pearson correlation coefficient (r) was calculated to evaluate the association between increased TT-TG distance and its anatomical parameters, and factors that met the inclusion criteria of P < .05 and r ≥ 0.30 were analyzed via stepwise multivariable linear regression analysis to predict TT-TG distance.Results:The LPD and control groups differed significantly in TT-TG distance, TTL, TFR, and MAD (P < .001 for all). Increased TT-TG distance was significantly positively correlated with TTL (r = 0.376; P < .001), femoral anteversion (r = 0.166; P = .036), TFR (r = 0.574; P < .001), and MAD (r = 0.415; P < .001), and it was signficantly negatively correlated with trochlear groove medialization (r = −0.178; P = .024). The stepwise multivariable analysis revealed that higher TTL, excessive knee external rotation, and excessive knee valgus were statistically significant predictors of greater TT-TG distance (P < .001 for all). The standardized estimates that were used for evaluating the predictive values were larger for TFR compared with those for TTL and MAD.Conclusion:TTL, TFR, and MAD were the main independent anatomical components associated with increased TT-TG distance, with the most prominent component being TFR. The association of TT-TG distance to each component analyzed in our study may help guide surgical planning.

Poster 226: Autograft versus Allograft for Medial Patellofemoral Ligament Reconstruction: A Systematic Review

Objectives:Patients with recurrent lateral patellar dislocations are often treated with reconstruction of the medial patellofemoral ligament (MPFL). The purpose of this study was to perform a systematic review to evaluate clinical outcomes and the risk of recurrent patellar dislocation following medial patellofemoral ligament reconstruction (MPFLR) with autograft versus allograft.Methods:A systematic review was performed by searching PubMed, the Cochrane Library, and Embase to identify studies comparing outcomes of MPFLR with autograft versus allograft. The search phrase used was: medial patellofemoral ligament reconstruction autograft allograft. The inclusion criteria were full-text studies that directly compared clinical outcomes and/or risk of recurrent patellar instability events between patients undergoing MPFLR with autograft versus allograft. A quality assessment was performed using the Modified Coleman Methodology Score (MCMS). Risk of bias was performed using the ROBINS-I and the Cochrane Collaboration’s risk of bias tools.Results:Seven studies (one level II, three level III, three level IV) were identified that met inclusion criteria, including a total of 150 patients who underwent MPFLR with autograft and 193 with allograft (Figure 1, Table 1). All studies showed a moderate risk of bias due to confounding, and five studies showed a moderate risk of bias for using non-blinded but identical postoperative protocols. All six studies showed serious risk of bias for using physicians not blinded to the treatment group (Figure 2). One study found a significantly higher failure rate among autograft patients, and another study found a trend toward a significantly higher failure rate among autograft patients (Table 2). One study demonstrated no significant difference between tibial tubercle-trochlear groove distance (measured on magnetic resonance imaging) in failed versus successful grafts. One study found that patellar tilt angle improved significantly from preoperatively to postoperatively (p<0.001), but there was no difference between the groups. Kujala scores significantly improved for both autograft and allograft patients across studies. Two studies found significant differences in postoperative Kujala scores between the two groups, one of which found better scores in allograft patients (p=0.0032) and another in which scores were better in autograft patients (p=0.02).Conclusions:This is the first systematic review limited to comparative studies comparing autograft versus allograft for MPFL reconstruction. Patients undergoing MPFLR with either autograft or allograft can expect to experience improvement in clinical outcomes. Graft failure was more frequently observed in autograft patients. Subjective outcomes improved to a similar degree in both groups. Allograft may be a better option for MPFLR due to lower failure rate.Figure 1.Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.Figure 2.ROBINS-I risk of biasTable 1.Study characteristicsTable 2.Failure rates.

Paper 53: Comparing Graft Choice in Medial Patellofemoral Ligament Reconstruction

Objectives:Disruption of the medial patellofemoral ligament (MPFL) may lead to recurrent lateral patellar dislocation and patellofemoral chondral injury. Optimal graft choice for MPFL reconstruction in the surgical treatment of patellar instability is unknown. While autograft remains readily available, easily harvested, and of lower cost, allograft is a viable alternative and portends several benefits over autograft. Autograft may provide superior strength or lower re-tear rate, but allograft has been shown to have similar outcomes with less donor site morbidity in some series. Overall, there is a paucity of research comparing autograft vs allograft in MPFL reconstruction. Prior studies have been limited by small sample sizes, incomplete data, or heterogeneous patient population. The objectives of this study were to compare outcomes scores, return to activity and revision rates between allograft and autograft in MPFL reconstruction. The authors hypothesized that there would be no significant difference in outcomes between those who received an allograft and those who received an autograft in MPFL reconstruction.Methods:Patients who underwent isolated MPFL reconstruction with allograft or autograft at a single institution between 2013-2020 were retrospectively reviewed. Patients with a follow-up of less than 2 years were excluded, along with those who underwent concomitant tibial tubercle osteotomy or trochleoplasty. Patients were contacted to complete functional assessments including the Single Assessment Numeric Evaluation (SANE), Visual Analog Scale for pain (VAS), and International Knee Documentation Committee (IKDC) scores. Patient demographics and complications were also reviewed. Outcomes were compared between those that underwent allograft and autograft MPFL reconstructionResults:Out of the fourty-six patients that were retrospectively reviewed, thirty-one (67.4%) patients underwent allograft reconstruction, while fifteen (32.6%) patients underwent autograft reconstruction. There were no differences between the two groups in age at surgery (25.2 years old in allograft vs 26.3 years old in autograft group, P=0.726), sex ratio (19F/12M in allograft and 9F/6M in autograft, P=1.000), or BMI (27.0 in allograft and 24.8 in autograft, P=0.179).There was a mean follow up duration of 4.57 years in the allograft group and 4.83 years in the autograft group (P=0.672), with an overall response rate of 70.2%. There were no differences between the two groups when assessing subjective pain using SANE (66.7 in allograft vs 74.5 in autograft, P=0.334) or VAS score (35.7 in allograft vs 22.9 in autograft, P=0.110). Further there were no differences in patient outcomes as assessed by IKDC score (68.3 in allograft vs 76.2 in autograft, P=0.247). Patients who received an allograft returned to activity at an average of 5.9 months, while patients who received an autograft returned to activity at an average of 5.2 months (P=0.416). One patient in the allograft group required revision surgery (P=0.246).Conclusions:Both allograft and autograft remain viable options in MPFL reconstruction. There were no significant differences in failure rates, PROs, pain, or time to return to play between allograft and autograft MPFL reconstruction in this series.

Mental and physical health-related quality of life in patients with recurrent patellar dislocations—a generic and disease-specific quality of life questionnaire assessment

PurposeThere is a paucity of quality of life (QoL) assessments in studies evaluating patients treated for recurrent lateral patellar dislocation (LPD). The primary aim of this study was to investigate whether mental well-being is impaired in patients with chronic (recurrent) LPD and, if so, to assess whether the mental health-related QoL dimension improves equivalently to the physical-related QoL dimension after successful surgical treatment.MethodsThirty-eight patients with recurrent LPD over a mean course of the disease of 4.7 ± 3.9 years (1—18 years) prior to surgery were included. Generic health-related QoL (HRQoL) (Short Form 36; SF-36) and disease-specific QoL (Banff Patella Instability Instrument 2.0; BPII 2.0) were assessed preoperatively and after a mean follow-up of 3.5 ± 0.8 years (2 – 5 years) postoperatively.ResultsUntreated LPD significantly impacted the physical dimension of patients’ generic HRQoL and their disease-specific QoL. When compared to age-equivalent normative data sets, the mental HRQoL dimension was not reduced prior to operative treatment but increased during the follow-up period. Surgical treatment normalized the physical dimension of patients’ generic HRQoL and significantly improved their disease-specific QoL. However, BPII 2.0 values remained reduced, albeit patellae were successfully stabilized.ConclusionThe results of this study indicate that patients with recurrent LPD are generally in good mental health, although physical impairment is striking. Notwithstanding that surgery prevented further dislocations and normalized the generic HRQoL, the disease-specific QoL remained reduced as far as this can be interpreted without population-based data.Level of evidenceLevel IV; Retrospective case series.

Distalization of the Tibial Tubercle for Patellar Stabilization Combined With Medial Patellofemoral Ligament Reconstruction: Length of Distalization or Residual Patella Alta and its Affect on Outcome

Background: Previous research supports that distal translation of the tibial tubercle osteotomy (dTTO) for patients with recurrent lateral patellar dislocation (R-LPD) and patella alta is effective for surgical patellar stabilization. Hypothesis/Purpose: The main purpose of this article is to evaluate (1) the results of modifying the surgical threshold and postoperative goal of patellar height measurements for surgical stabilization originated in the “menu à la carte” approach to patellar surgical stabilization and (2) the relationship between the distance distalized in millimeters and postoperative complications. Our hypothesis was that dTTO with medial patellofemoral ligament reconstruction (MPFL-R) will successfully stabilize the patella with improvement in outcome scores and few complications, using a modification of the original menu à la carte as our surgical algorithm. Study Design: Case series; Level of evidence, 4. Methods: A total of 68 consecutive patients with R-LPD underwent dTTO and MPFL-R for surgical patellar stabilization by a single surgeon between May 2009 and September 2015. Surgical indications were R-LPD combined with patella alta. The surgical threshold for dTTO was Caton-Deschamps index (CDI) or Insall-Salvati ratio ≥1.4 and/or a patellar trochlear index <0.15. The postoperative surgical goal for patellar height was a CDI of 1.1 to 1.2. Length of the distalization was computed by using the CDI measurement as the primary intraoperative guide and measured intraoperatively with a ruler. Clinical, radiographic, and patient outcome measures were reviewed. Results: The mean CDI preoperatively was 1.40 and postoperatively it was 1.09. The mean distalization was 9.9 mm (range, 4-15 mm). Three patients (4.4%) had frank R-LPD postoperatively. Ten patients had residual patella alta (CDI >1.2), with 1 redislocation. Mean postoperative CDI in the recurrent dislocation group was 1.13 (range, 1.06-1.25) as compared with 1.09 (range, 0.92-1.35) in the nonrecurrent group (P = 0.65). Complications included 3 tibial fractures (4.4%) and postoperative knee arthrofibrosis in 6 patients (8.8%), with mean distalization greater in the arthrofibrosis group (P = .04). Knee injury and Osteoarthritis Outcome Score (KOOS) values improved in all domains, including a 31–point increase in Quality of Life. Conclusion: dTTO with MPFL-R for patients with patella alta leads to a high rate of normalization of patellar height measurements (87%) and patellar stabilization (95.6%). Residual patella alta is not associated with an increased risk of recurrence. The length of dTTO up to 15 mm is not associated with an increase in postoperative complications, except for an increased prevalence of arthrofibrosis (8.8%).

Medial patellofemoral ligament reconstruction is superior to active rehabilitation in protecting against further patella dislocations

PurposeIsolated reconstruction of the medial patellofemoral ligament (MPFL-R) has become the predominant stabilizing procedure in the treatment of recurrent lateral patellar dislocation (LPD). To minimize the risk of re-dislocations, isolated MPFL-R is recommended in patients with no significant trochlea dysplasia and tibial tuberosity trochlear groove distance < 20 mm on computed tomography (CT). Incidentally, these criteria are the same that are used to identify first time LPD patients where conservative treatment is recommended. The purpose of this study was therefore to compare MPFL-R with active rehabilitation for patients with recurrent LPD (RLPD) in absence of the above mentioned underlying anatomical high-risk factors for further patellar dislocations.MethodsRLPD-patients aged 12–30 without underlying anatomical high-risk factors for further LPD were randomized into treatment either with isolated MPFL-R or active rehabilitation provided and instructed by a physiotherapist. All patients underwent diagnostic arthroscopy for concomitant problems. The main outcome measure was persistent patellar instability at 12 months. Knee function at baseline and 12 months was asses using the following patient reported outcomes measures (PROMS); KOOS, Kujala, Cincinnati knee rating, Lysholm score and Noyes sports activity rating scale.ResultsBetween 2010 and 2019, 61 patients were included in the study (MPFL-R, N = 30, Controls, N = 31). Persistent patellar instability at 12 months was reported by 13 (41.9%) controls, versus 2 (6.7%) in the MPFL-group (RR 6.3 (95% CI 1.5–25.5). No statistically significant differences in activity level were found between the MPFL-group and the Controls at neither baseline nor follow up. The patients with persistent instability at 12 months did not score significantly lower on any of the PROMs compared to their stable peers, regardless of study group.ConclusionPatients with recurrent patellar dislocations have a six-fold increased risk of persistent patellar instability if treated with active rehabilitation alone, compared to MPFL-R in combination with active rehabilitation, even in the absence of significant anatomical risk factors. Active rehabilitation of the knee without MPFL-R improves patient reported knee function after one year, but does not protect against persistent patellar instability.Level of evidence1.

The Patellar Instability Probability Calculator: A Multivariate-Based Model to Predict the Individual Risk of Recurrent Lateral Patellar Dislocation

Background: Predicting the risk of recurrence is of great interest when counseling patients after primary lateral patellar dislocation (LPD). Purpose: To investigate a multivariate model to predict the individual risk of recurrent LPD. Study Design: Case-control study; Level of evidence, 3. Methods: The study population included patients with primary LPD, knee imaging, and a minimum 2-year follow-up after nonoperative treatment. Data including patient characteristics and anatomic patellar instability risk factors were collected retrospectively from 7 national study centers. Bivariate and multivariate regression analyses were carried out to identify risk factors for recurrent LPD and to generate an accuracy-optimized model for out-of-sample prediction. Results: In total, 115 of 201 patients (57%) experienced recurrent LPD within 2 years after primary LPD. Age ≤16 years at primary LPD (odds ratio [OR], 5.0), history of contralateral instability (OR, 2.4), and trochlear dysplasia (Dejour type B-D: OR, 2.5; lateral trochlear inclination ≤12°: OR, 2.7) were significant risk factors for recurrent LPD (P < .05). The prediction accuracy including these 3 risk factors was 79%. Patella alta, an increased tibial tubercle to trochlear groove distance, and patellar tilt had neither an association with increased recurrence rates nor an influence on prediction accuracy of recurrent LPD. Conclusion: Young age and trochlear dysplasia are major risk factors for early recurrent LPD. A multivariate model including age at primary LPD, lateral trochlear inclination, and history of contralateral LPD achieved the highest prediction accuracy. Based on these findings, the patellar instability probability calculator is proposed to estimate the individual risk of early recurrence when counseling patients after primary LPD.

Is an individually tailored programme of intense leg resistance and dynamic exercise acceptable to adults with an acute lateral patellar dislocation? A feasibility study

BackgroundLateral patellar dislocations mainly affect active teenagers and young adults. To help people recover, non-surgical exercise-based treatment is often recommended but the optimal exercise-based treatment is unknown. Currently, treatment outcomes after this injury are variable. Common problems include recurrent dislocation, reduced activity levels, and later surgery. A programme of intense leg resistance exercises, and dynamic exercises related to participants’ activity-related goals, has rationale, but has not been previously reported. In line with the Medical Research Council guidance, this study aimed to assess the acceptability of a novel evidence-based exercise programme for adults after acute lateral patellar dislocation and the feasibility of future research evaluating this treatment.MethodsA single-group prospective study was conducted at the John Radcliffe Hospital, Oxford, UK. Participants were 16 years or older with an acute first-time or recurrent lateral patellar dislocation. Participants received up to six face-to-face, one-to-one, physiotherapy sessions, over a maximum of 3 months, and performed intensive home exercises independently at least three times per week. Strategies to increase exercise adherence were used. Primary objectives were to determine the number of eligible patients, the recruitment rate (proportion of eligible patients that provided written informed consent), participant adherence to scheduled physiotherapy sessions and self-reported adherence to prescribed exercise, and intervention acceptability to participants measured by attrition and a study-specific questionnaire. Data were analysed using descriptive statistics.ResultsFifteen of 22 (68%) patients with a lateral patellar dislocation were eligible. All eligible (100%) were recruited. Two of 15 (13%) participants provided no outcome data, 2/15 (13%) provided partial outcome data, and 11/15 (73%) provided all outcome data. Questionnaire responses demonstrated high intervention acceptability to participants. Participants attended 56/66 (85%) physiotherapy sessions and 10/11 (91%) participants reported they ‘always’ or ‘often’ completed the prescribed exercise. One participant redislocated their patella; another experienced knee pain or swelling lasting more than one week after home exercise on three occasions.ConclusionThe intervention appeared acceptable to adults after acute lateral patellar dislocation, and a future randomised pilot trial is feasible. This future pilot trial should estimate attrition with increased precision over a longer duration and assess participants’ willingness to be randomised to different treatments across multiple centres.Trial registrationClinicalTrials.govNCT03798483, registered on January 10, 2019

The novel dynamic MPFL-reconstruction technique: cheaper and better?

PurposeReconstruction of the medial patellofemoral ligament (MPFL) is an established procedure to restore patellar stability. Aim of this study is to evaluate the results of a dynamic MPFL reconstruction technique in a large university hospital setting.MethodsTwo hundred and thirteen consecutive patients with 221 knees were surgically treated for recurrent lateral patellar dislocation. All patients obtained dynamic reconstruction of the MPFL with detachment of the gracilis tendon at the pes anserinus while maintaining the proximal origin at the gracilis muscle. Patellar fixation was performed by oblique transpatellar tunnel transfer. Follow-up data including Kujala and BANFF score, pain level as well as recurrent patella instability were collected at a minimum follow-up of 2 years.ResultsFollow-up could be obtained from 158 patients (71%). The mean follow-up time was 5.4 years. Mean pain level was 1.9 ± 2.0 on the VAS. Mean Kujala score was 78.4 ± 15.5. Mean BANFF score was 62.4 ± 22.3. MPFL-reconstructions that were performed by surgeons with a routine of more than ten procedures had a significantly shorter surgical time 52.3 ± 17.6 min. Male patients yielded higher satisfaction rates and better clinical scores compared to females. Complications occurred in 27.2% of procedures, 20.9% requiring revision surgery of which were 9.5% related to recurrent patellar instability. 78% of all patients indicated they would undergo the procedure again.ConclusionDynamic MPFL reconstruction presents a reproducible procedure with increased complication rates, inferior to the results of static reconstruction described in the literature. Despite, it appears to be an efficient procedure to restore patellar stability in a large university hospital setting, without the necessity for intraoperative fluoroscopy.Trial registrationThe study was registered in ClinicalTrials.gov with the registration number NCT04438109 on June 18th 2020.

Autograft Versus Allograft for Medial Patellofemoral Ligament Reconstruction: A Systematic Review.

Background:Patients with recurrent lateral patellar dislocations are often treated with reconstruction of the medial patellofemoral ligament (MPFL).Purpose:To perform a systematic review to evaluate clinical outcomes and the risk of recurrent patellar dislocation after MPFL reconstruction (MPFLR) with autograft versus allograft.Study Design:Systematic review; Level of evidence, 4.Methods:The authors conducted a search of PubMed, the Cochrane Library, and Embase to identify studies comparing outcomes of MPFLR with autograft versus allograft. The inclusion criteria were full-text studies that directly compared clinical outcomes and/or risk of recurrent patellar instability between patients undergoing MPFLR with autograft versus allograft. A quality assessment was performed using the modified Coleman Methodology Score, and risk-of-bias assessment was performed using the Risk Of Bias In Non-randomized Studies–of Interventions and the Cochrane Collaboration tools.Results:Seven studies (1 evidence level 2, 3 level 3, 3 level 4) that met inclusion criteria were identified and included a total of 150 patients who underwent MPFLR with autograft and 193 with MPFLR with allograft. One study found a significantly higher failure rate among patients with autograft, and another study found a trend toward a significantly higher failure rate among patients with autograft. One study demonstrated no significant difference between postoperative tibial tubercle–trochlear groove distance (measured on magnetic resonance imaging scans) in failed versus successful grafts. One study found that patellar tilt angle improved significantly from preoperatively to postoperatively (P < .001) but there was no difference between the groups. Kujala scores significantly improved for both autograft and allograft groups across studies. Two studies found significant differences in postoperative Kujala scores between the 2 groups, 1 of which found better scores in the allograft group (P = .0032) and another in which scores were better in the autograft group (P = .02).Conclusion:Patients undergoing MPFLR with either autograft or allograft can expect to experience improvement in clinical outcomes. Subjective outcomes improved to a similar degree in both groups. Graft failure was more frequently observed in patients with autograft. Allograft may be a better option for MPFLR owing to lower failure rate.