PATELLAR DISLOCATION AND PATELLAR INSTABILITY PANORAMIC REVIEW

The purpose of this study was to investigate the Danish population as a whole from 1994 to 2013 to find the incidence of acute and recurrent patellar dislocation. The study was performed as a descriptive epidemiological study. The Danish National Patient Registry was retrospectively searched from 1994 to 2013 to find the number of acute and recurrent patellar dislocation. National population data were collected from Statistics Denmark. The period 1994-2013 saw a total registration of 24,154 primary patellar dislocations. A mean incidence of 42 (95% CI 37-47) per 100,000 person-years at risk was found, and young females aged 10-17 had the highest incidence of 108 (95% CI 101-116). In a 10-year follow-up, patients were at an overall risk of 22.7% (95% CI 22.2-23.2) of suffering a recurrent dislocation, with young girls aged 10-17 experiencing the highest risk, namely 36.8% (95% CI 35.5-38.0). The overall risk of suffering a patellar dislocation in the contralateral knee was 5.8% (95% CI 5.5-6.1) and 11.1% (95% CI 10.4-11.7) for patients aged 10-17. A high incidence rate of primary patellar dislocation was found both as a mean in the population (42/100,000), and particularly in patients aged 10-17 (108/100,000). The risk of recurrent dislocation in the affected knee (22.7%) and the contralateral knee (5.8%) was high, which could indicate the influence of an underlying pathomorphology. This is relevant knowledge to the clinician, as he/she should be aware of the high risk of recurrent dislocation when deciding on treatment, especially in young patients. IV.

Primary patellar dislocation or first-time patellar dislocation is the second most frequent cause of knee injuries which overall accounts for about 3% of other knee injuries. The patellofemoral joint is formed by the patella connecting to the femoral trochlea and creates both static and dynamic structures of the knee. There are basically three types of patellar dislocation: superior, lateral, and medial. The lateral dislocation is the most frequent one.Females are more vulnerable and are at higher risk than males. Muscular weakness or muscular imbalance leads to patellar instability, and ultimately to dislocation. The recurrence rate after primary patellar dislocation is 15-60%. This case report is of a 31-year-old female with patelladislocation with a medial meniscal tear and a case of early osteoarthritis for whom we planned goal-oriented physiotherapy rehabilitation week-wise and progressed every week. The assessment was taken before and after physiotherapy rehabilitation.The patient was managed conservatively with a long knee brace, and physiotherapy started after one month. Due to prolonged immobilization, the patient suffered from quadriceps muscle atrophy. The physiotherapist focused on biomechanism and got the expected results in pain reduction, regaining strength, and improving range of motion, and the patient was able to walk properly without taking any supportafter rehabilitation.

Femoral trochlear dysplasia is an anatomic deformity that predisposes patients to patellar instability, including patellar subluxation and dislocation, and can lead to severe patellofemoral joint degeneration if left untreated. Femoral trochlear dysplasia leading to recurrent bilateral patellar dislocation has rarely been reported as having a familial association. Orthopedic surgeons who encounter patients presenting with chronic patellar instability with no underlying disease or syndrome should be aware of the presence of femoral trochlear dysplasia leading to recurrent bilateral patellar dislocation. Although femoral trochlear dysplasia remains uncommon, the presence of bilateral recurrent patellar dislocation in multiple members of the same family is highly suggestive of genetic inheritance.This article describes 3 patients from 1 family who presented with femoral trochlear dysplasia leading to recurrent bilateral patellar dislocation. To our knowledge, this is the second article to describe a familial form of femoral trochlear dysplasia associated with recurrent bilateral patellar dislocation and is the first article in English. A lower threshold for screening and early intervention for symptomatic family members may be indicated to prevent the long-term effects of chronic patellar subluxation, dislocation, and patellofemoral arthritis.

What's New in Pediatric Orthopaedic Surgery.

Patellar instability occurs mainly in young patients and shows a high incidence of concomitant cartilage injuries. Recently there has been a strong attempt to identify risk factors and enhance imaging techniques to detect patients with an increased risk for recurrent patella dislocation.We describe current findings on factors associated with recurrent patella dislocation in the adolescent. Trochlear dysplasia, patellar height, patellar tilt, tibial tuberosity-trochlear groove distance, skeletal maturity, and history of contralateral patellar dislocation are well known significant risk factors for recurrence in adolescent patients. Predictive models to calculate risk of recurrence have been reported recently. The Patellar Instability Severity Score was the first to include demographic and anatomic factors, which is of major value when counseling patients and relatives. Several classification systems to predict the rate of recurrence after primary patella dislocation have been presented over the last years. Anatomic risk factors such as skeletal immaturity, trochlear morphology, patellar height, patellar tilt, and elevated tibial tuberosity-trochlear groove distance have been investigated. However, there is still a lack of knowledge as to how single risk factors or their interaction with each other may contribute.

The purpose of this study was to investigate incidence, nature, and risk factors of primary traumatic patellar dislocations. We identified acute first-time traumatic patellar dislocations from a national hospital discharge register. Patients with previous patellar dislocations, subluxations, or knee traumas were excluded. The sample consisted of 128,714 Finnish male conscripts (median age 20). Background risk factor data were obtained from a Finnish conscript service database. The dislocators were observed during their service period for a short-term outcome. From the 128,714 male conscripts, 278 had patellar dislocations, and 72 were classified as having sustained first-time traumatic patellar dislocations. The 128,436 nondislocators served as a control group. The incidence of acute traumatic primary patellar dislocations among male conscripts was 77.4 (95% CI: 61.1-96.8) per 100,000 persons per year. The male patients with traumatic primary patellar dislocations were taller (P = 0.03) and weighed more (P = 0.02) than the controls. Hemarthrosis was present in all patients, and when MRI or open surgery was performed, medial retinacular disruption and medial patellofemoral ligament (MPFL) injury were identified. Patients' return to military service was unrelated to the choice of treatment. Primary patellar dislocation is not a negligible cause of morbidity among young male adults. It can be concluded that hemarthrosis and MPFL rupture are the definite signs of an acute traumatic primary patellar dislocation. Height and weight were significant risk factors, whereas poor physical performance was not associated with primary patellar dislocation.

The patellofemoral instability is pathology of the adolescent and young adult. An important contributory factor is trochlear dysplasia, which may cause patellar recurrent dislocation. Trochleoplasty pretends to recreate the patellofemoral biomechanical stability. The authors present a case report of a young woman, combat sports practitioner, with trochlear dysplasia and patellar recurrent dislocation. The patient did a trochleoplasty and was submitted to a rehabilitation programme, with good outcome. In this case report diagnosis, treatment and follow-up results are discussed. Keywords: Patellar Instability; Patellar Dislocation; Rehabilitation.

Primary patellar dislocation is often the initial manifestation of patellofemoral instability. Its long-term consequences can include recurrent dislocation and permanent dysfunction of the knee joint. There is no consensus on the optimal treatment of primary patellar dislocation in the relevant literature. The main prerequisite for a good long-term result is a realistic assessment of the risk of recurrent dislocation. We carried out a systematic literature search in OvidSP (a search engine for full-text databases) and MEDLINE to identify suitable stratification models with respect to the risk of recurrent dislocation. In the ten studies included in the current analysis, eight risk factors for recurrence after primary patellar dislocation were identified. Six studies revealed a higher risk in younger patients, particularly those under 16 years of age. The sex of the patient had no clear influence. In two studies, bilateral instability was identified as a risk factor. Two anatomical risk factors-a high-riding patella (patella alta) and trochlear dysplasia-were found to have the greatest influence in six studies. In a metaanalysis of five studies, patella alta predisposed to recurrent dislocation with an odds ratio (OR) of 4.259 (95% confidence interval [1.9; 9.188]). Moreover, a pathologically increased tibial tuberosity to trochlear groove (TT-TG) distance and rupture of the medial patellofemoral ligament (MPFL) on the femoral side were associated with higher recurrence rates. Patients with multiple risk factors in combination had a very high risk of recurrence. The risk of recurrent dislocation after primary patellar dislocation is increased by a number of risk factors, and even more so when multiple such risk factors are present. Published stratification models enable an assessment of the individual risk profile. Patients at low risk can be managed conservatively; surgery should be considered for patients at high risk.

Introduction. Patellofemoral instability is a troublesome condition that results in significant morbidity, frequently associated with persistent anterior knee pain, long-term osteoarthritis and reduced quality of life. Purpose. The purpose of this study was to describe functional outcomes following surgical treatment of patients who underwent Elmslie-Trillat procedure and reconstruction of medial patellofemoral ligament (MPFL) correlated with Elmslie-Trillat in the treatment of recurrent patellar dislocation and subluxation. Methods. We prospectively followed 23 patients (24 knees) with patellofemoral instability who underwent realignment surgery procedures between 2015 and 2017, 14 knees by the Elmslie-Trillat procedure (Group 1) and 10 knees by Elmslie-Trillat combined with MPFL reconstruction (Group 2). The patients were evaluated pre and postoperatively by clinical examination, knee radiographs, CT scans and functional outcome Kujala score. Results. At a follow up period of 2 years, the apprehension sign remained positive in 6 knees in Group 1, and only one in Group 2. On the skyline radiographs and axial CT scans, stability was significantly better in group 2 than in group 1. The mean Kujala score was 65.2+/ -9.39 points in group 1, and 87.1+/ -6.43 points in group 2, at 2 years evaluation, significantly higher than before surgery. No patient developed osteoarthritis while being followed up. Conclusion. Based on these findings, we were able to conclude that the reconstruction of the MPFL combined with the osteotomy of distal tuberosity is a useful treatment of recurrent patellar dislocation and subluxation. However, further studies are needed to assess the impact of the realignment procedures in the prevention of joint degeneration.

The Recurrent Instability of the Patella Score: A Statistically Based Model for Prediction of Long-Term Recurrence Risk After First-Time Dislocation

Objective To evaluate the clinical efficacy of autologous semitendinosus tendon and double bundles reconstruction of medial patellofemoral ligament(MPFL) in the treatment of recurrent patellar dislocation without bone deformity. Methods The retrospective analysis was performed on the clinical data of 12 patients with recurrent patellar dislocation without bone deformities who were reconstructed by autologous semitendinosus tendon in Wuhu Hospital of Traditional Chinese Medicine from June 2015 to December 2017, including 2 males and 10 females, aged 14-46(27.75±10.14) years. All patients whose lateral patellar anchor nail fixed graft using two belt line, the femur after adjusting the tension side under arthroscopy using extrusion screw implant interface, postoperative 1, 3, 6 and 12 months follow-up, subjective evaluation of patellofemoral joint friction feeling, patellar abnormal activities, patellar extrapolation experiment and extrapolation of fear, the knee joint motion, muscle strength test. Imaging(X-ray) was used to evaluate the position of the bone tract, and Lysholm, Tegner and Kujala scores were used to evaluate the knee function before and after surgery. Results All 12 patients were successfully operated, and were followed up for 12 to 24 months, mean 13.5 months. No patella redislocation or patella dislocation were found after operation.0° and 30° bend knees a patellar extrapolation experiment and extraopolation fears were negative. The lysholm score was preoperative 66.00±4.71 and the final follow-up 92.67±3.23.Tegner score was preoperative 3.33±0.89 and the final follow-up 5.33±0.78.The subjective scores of Kujala were preoperative 53.67 ±3.23 and final follow-up 91.50±2.68, with statistically significant differences(t=16.248, 32.176, 89.350, all P values<0.01). Conclusions MPFL is a safe, effective and reliable method and can achieve satisfactory clinical result for the reconstruction of MPFL with autologous semitendinosus tendon and double beam anatomic reconstruction in patients with recurrent patrllar dislocation. Key words: Patella dislocation; Recurrent patellar dislocation; Medial patellofemoral ligament; Reconstructive surgical procedures

BackgroundRecurrent patellar dislocation is the result of anatomical alignment and imbalance of restraint of bone and soft tissue. We investigate the anatomical characteristics of the knee joint in a family of patients with recurrent patella dislocation, and to screen the possible pathogenic genes in this family by whole exome sequencing in 4 patients and 4 healthy subjects, so as to provide theoretical basis for the pathogenesis of this disease.MethodsThe data related to patella dislocation were measured by imaging data. The peripheral blood DNA of related family members was extracted for the whole exome sequencing, and then the sequencing results were compared with the human database. By filtering out synonymous variants and high-frequency variants in population databases, and then integrating single nucleotide non-synonymous variants of family members, disease-causing genes were found.ResultsAll patients in this family have different degrees of abnormal knee anatomy, which is closely related to patella dislocation. The sequencing results of patients and normal persons in this patella dislocation family were compared and analyzed, and the data were filtered through multiple biological databases. Find HOXB9 (NM_024017.4:c.404A>G:p.Glu135Gly),COL1A1(NM_000088.3:c.3766G>A:p.Ala1256Thr),GNPAT(NM_014236.3:c1556A>G:p.Asp519Gly),NANS(NM_018946.3:c.204G>C:p.Glu68Asp),SLC26A2(NM_000112.3:c.2065A>T:p.Thr689Ser) are nonsynonymous variants (MISSENSE). Through Sanger sequencing, the identified mutations in HOXB9 and SLC26A2 genes were only present in samples from patients with recurrent patellar dislocation.ConclusionsThe patients with recurrent patellar dislocation had markedly abnormal knee anatomy in this family. HOXB9 gene and SLC26A2 gene were found to be the possible pathogenic genes or related genes for patella dislocation.

PurposeThe primary purpose was to assess sulcus angle (SA) magnetic resonance imaging (MRI) measurements and determine diagnostic cutoff values along four axial levels on cartilaginous and osseous surfaces comparing those with patellar dislocations (PD) versus controls. A secondary aim was to identify differences in SA between patients with one‐time dislocation (OTD) versus recurrent patellar dislocations (RPDs).MethodsPaediatric patients with a history of PD were retrospectively grouped into those with an OTD versus RPDs. Age and sex frequency matching controls (ACL injuries without PD history) were identified. The SA was recorded at four levels in the trochlear groove (TG) on cartilaginous and osseous surfaces. Differences between sample means (PDs vs. controls; RPDs vs. OTDs) were assessed; cutoff values for discriminating PDs from controls were identified utilising Youden′s index.ResultsThere were 173 PDs (106 RPDs, 67 OTDs) and 100 controls. There were differences in mean SA between PD and controls throughout the trochlear groove for both cartilaginous (PD vs. control: SA1 166.1° vs. 152.5°, SA2 161.0° vs. 148.5°, SA3 155.7° vs. 145.9°, SA4 150.7° vs. 142.5°) and osseous surfaces (PD vs. control: SA1 160.2° vs. 146.6, SA2 153.8° vs. 140.2°, SA3 147.2° vs. 134.8°, SA4 142.1° vs. 132.6°) (p < 0.001). Diagnostic cutoffs were higher for cartilaginous versus osseous measurements (SA1 159.6° vs. 153.1°, SA2 153.8° vs. 148.0°, SA3 152.5° vs. 141.6°, SA4 148.1° vs. 137.4°). RPD patients had greater cartilaginous SA than OTDs throughout the TG (SA1p = 0.014, SA2p = 0.004, SA3p = 0.027, SA4p = 0.007), while osseous SA measurements did not differ (SA1p = 0.057, SA2p = 0.070, SA3p = 0.185, SA4p = 0.175).ConclusionsSA was greater in PDs than controls at all four levels in the TG for both cartilaginous and osseous measurements. Cartilaginous SA was greater among RPDs than OTDs at all levels; however, osseous SA was not different between cohorts. The diagnostic cutoff of dysplastic SA differed by axial level and surface.Level of EvidenceLevel III.

PurposeLangenskiöld described a reconstructive soft-tissue procedure for irreducible lateral congenital patellar dislocations. Paley further detailed the technique in the surgical management of congenital femoral deficiency. The aim of this study was to evaluate the outcomes of patients with congenital, chronic and recurrent patellar dislocations treated with the modified Langenskiöld procedure.MethodsThis is a retrospective case series. Between 2011 and 2018, 18 knees in 13 patients (mean age 15.8 years (sd 4.4; 12 to 29.9), nine female) with diagnoses of recurrent (six patients, eight knees), chronic (four patients, six knees) and congenital (three patients, four knees) patellar dislocations were treated with the modified Langenskiöld procedure.ResultsThere were no recurrent lateral dislocations in the congenital or recurrent groups. One of the patients in the congenital group had an overcorrection with some medial patellar maltracking but until this time has not required any further surgery. In the chronic group two of the six knees developed further dislocations; these were both on the same patient, who had no dislocations until one year after surgery. Mean Kujala score was 83.7 (sd 17; 47 to 100) for all groups. In spite of preoperative knee flexion contractures of up to 30° in three patients (six knees), all patients had full extension postoperatively. Eight patients reported being satisfied with their outcome, one was somewhat satisfied, two were very dissatisfied, and two did not respond.ConclusionThe modified Langenskiöld reconstruction provides a powerful correction for challenging cases of congenital and recurrent patellar dislocations. Re-dislocation as well as overcorrection can occasionally occur.Level of EvidenceLevel IV

This article sought to determine rates for return to work, pain relief, and recurrent patellofemoral instability for military service members undergoing tibial tubercle osteotomy (TTO) for persistent lateral patellar subluxation or dislocation. Patient demographic and surgical variables were isolated from the medical records of active duty service members with at least 2 years of postoperative follow-up, and correlated with return to work, pain improvement, recurrent patellofemoral instability, and perioperative complications. There were 51 service members (58 primary TTOs) with an average follow-up of 3.3 (range, 2.0-6.7) years. Service members had an average of 2.8 (1-12) instability events preoperatively. At a minimum of 2 years postoperatively, 41 (80%) military service members returned to full active duty service. Among the 58 TTOs, there was a 46% improvement in the patient-reported visual analog score from 4.1 to 2.2 (p < 0001). The postoperative recurrent instability rates were patellar dislocation (5.1%) and patellar subluxation (15.5%). Concomitant proximal realignment was performed in 48% of cases, which did not affect return to service, postoperative patellar instability events, or pain improvement (p > 0.05). The overall complication rate was 10%. Postoperative tibial fractures occurred in 6.9% of TTOs. At short- to mid-term follow-up, 80% of service members undergoing TTO for patellofemoral instability returned to military duty with significant improvement in pain scores and a moderate perioperative complication and postoperative instability rate. This study is a level IV therapeutic case series.