To determine in skeletally mature patients with a traumatic, first-time, patellar dislocation, the effect of early MPFL reconstruction versus rehabilitation on the rate of recurrent patellar dislocations and functional outcomes. Three online databases MEDLINE, EMBASE and PubMed were searched from database inception (1946, 1974, 1966 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. A risk of bias assessment was performed for all included studies using the MINORS and Detsky scores. Overall, there were a total of 22 studies and 1705 patients included in this review. The pooled mean redislocation rate in 18 studies comprising 1409 patients in the rehabilitation group was 31% (95% CI 25%-36%, I2 = 65%). Moreover, the pooled mean redislocation rate in five 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 three studies comprising 67 patients in the reconstructive group was 91 (95% CI 84-97, I2 = 86%), compared to a score of 81 (95% CI 78-85, I2 = 78%) in 7 studies comprising 332 patients in the rehabilitation group. The reoperation rate was 9.0% in 936 patients in the rehabilitation group and 2.2% in 322 patients in the reconstruction group. Management of acute first-time patellar dislocations with MPFL reconstruction resulted in a lower rate of redislocation and a higher Kujala score, as well as noninferiority with respect to complication rates compared to nonoperative treatment. The paucity of high-level evidence warrants further investigation in this topic in the form of well-designed and high-powered RCTs to determine the optimal management option in these patients

Background. Patellar dislocation is a serious complication leading to patient morbidity following total knee arthroplasty. The cause can be multifactorial. Extensor mechanism imbalance may be present and result from technical errors such as malrotation of the implants. Methods. We performed a retrospective study assessing the outcomes of revision surgery for patellar dislocation in patients with component malrotation in both primary and revision total knee arthroplasty. Patient demographics, etiology of dislocation, presurgical deformity, intraoperation component position, complications, reoperation and knee society scores were collected. Results. Twenty patients (twenty-one knees) were identified. The average time from primary arthroplasty to onset of dislocation was 33.6 months (SD, 44.4), and the average time from dislocation to revision was 3.38 months (SD, 2.81). Seventeen knees (80.1%) had internal rotation of the tibial component and 7 knees (33.3%) had combined internal rotation of both the femoral and tibial components. Sixteen knees (76.1%) were treated with a condylar constrained implant at the time of revision, and 5 knees were converted to a hinged prosthesis. The average follow-up time was 56 months. During this time, one patient (4.54%) had a recurrent dislocation episode, requiring further surgery. At final follow up, the mean knee society score for the patient cohort was 86.2. Conclusion. Revision total knee arthroplasty to treat patellar dislocation in patients with malrotated components was associated with high success rates. After revision surgery, patients had a low recurrence of patellar dislocation, low complication rates, and excellent functional outcomes. For figures, tables, or references, please contact authors directly

Introduction. Recurrent patellar dislocation is often reported in bilateral knees in young active individuals. The medial patellofemoral ligament (MPFL) tear is the attributable cause behind many of them and warrants reconstruction of the ligament to stabilize the patellofemoral joint. Besides, trochleoplasty and Fulkerson's osteotomy are some other procedures that are performed to treat this problem. This study aimed to compare the clinical and functional outcomes in a cohort of patients with single-stage bilateral realignment procedures vs staged procedures. Methods. It was a retrospective matched cohort study with prospectively collected data. A total of 36 patients (mean age-26.9 years, range 13 years to 47 years) with recurrent patellar dislocations, who underwent a surgical correction in both the knees, were divided into two matched groups (age, sex, follow-up, and type of procedure). Among them, 18 patients had surgeries in one knee done at least six months later than the other knee. The remaining 18 patients had surgical interventions for both knees done in a single stage. Lysholm, Kujala, Tegner, and subjective knee scores of both groups were compared and analyzed. The rate of complications and return to the theatre were noted in both groups. Results. With a mean follow-up of 7.3 years (2.0 years to 12.3 years), there was a significant improvement in PROMS observed in both the groups (p<0.05). No significant difference could be found between the two groups in terms of the Lysholm, Kujala, and subjective knee scores (p> 0.05). The rate of complication and the re-operation rate was comparable in both the groups (p>0.05). Conclusion. The outcomes of staged vs simultaneous surgeries for bilateral patellofemoral instability are comparable. Our results indicate that simultaneous bilateral surgical correction is safe. This can potentially be an option to reduce the surgical cost and perioperative morbidity. However, careful selection of cases, choice of the patient, and the scope of rehabilitation facilities are some of the other factors that should be considered

Lateral patellar dislocation is a common cause of acute traumatic haemarthrosis in young active patients, usually occurring during sporting activites. However, patellar dislocation is usually transient with patients often unaware it has occurred. Often magnetic resonance imaging (MRI) offers the first diagnosis. Most patellar dislocations are treated conservatively with an emphasis on early return to movement. We report on a series of 30 patients who were diagnosed as having had a transient patellar dislocation by MRI from December 2001 to October 2007 as evidenced by the characteristic countercoup pattern of bone bruising seen on the lateral femoral condyle. In addition to the patellar findings, the images were reviewed with specific reference to the medial collateral ligament, a heretofore undescribed concomitant injury. During the study period, 30 patients (26 males, 4 females) were diagnosed on MRI as having had transient patellar dislocation. The mean age (mean +/− standard deviation) of the cohort was 23.1+/−6.1 years (range:14 – 36 years). In all but one case, normal anatomical alignment had been restored. In addition to multiple patellar chondral findings, the condition of the MCL was commented upon in 29 cases (97%). Of these, 12 (41%) had documented damage to the MCL. These injuries were classified as grade 1 (n=7), grade 2 (n=3) and grade 2/3 as defined by incomplete detachment of the MCL from the medial femoral condyle (n=2). These results serve to highlight the co-existence of MCL injuries with patellar dislocation to a relatively high incidence. This injury should be suspected and examined for in the case of prolonged symptoms after dislocation. In addition, the current vogue for early rehabilitation needs to be regarded with some circumspection

We investigated the clinical and radiological outcome of trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia in 38 consecutive patients (45 knees) with a mean follow-up of 8.3 years (4 to 14). None had recurrence of dislocation after trochleaplasty. Post-operatively, patellofemoral pain, present pre-operatively in only 35 knees, became worse in 15 (33.4%), remained unchanged in four (8.8%) and improved in 22 (49%). Four knees which had no pain pre-operatively (8.8%) continued to have no pain. A total of 33 knees were available for radiological assessment. Post-operatively, all but two knees (93.9%) had correction of trochlear dysplasia radiologically but degenerative changes of the patellofemoral joint developed in 30% (10) of the knees. We conclude that recurrent patellar dislocation associated with trochlear dysplasia can be treated successfully by trochleaplasty, but the impact on patellofemoral pain and the development of patellofemoral osteoarthritis is less predictable. Overall, subjective patient satisfaction with restored patellofemoral stability after trochleaplasty appeared to outweigh its possible sequelae

INTRODUCTION. It has been reported that the rate of complications around the patella after Total Knee Arthroplasty(TKA) is 1–12%, and the patella dislocation is the most common one. PURPOSE. We will report a case that had the patella dislocation after TKA caused by malrotation of the components. CASE. 67 years old, Female. The chief complaint was an instability of the right patella. She had undergone TKA due to osteoarthritis at another hospital. After 2 months, she felt a subluxation of the patella. And after 4 months, she had a reoperation of medial reefing and revision of the patella at the same hospital, and the doctor allowed her to flex her right knee within 70 degrees. However, after 3 months, she started experiencing pain with a feeling of dislocation and got it corrected and immobilized with a knee brace. 2 weeks later, she visited our hospital for the first time. STATUS. 148cm, 65kg. She could gait with an extension knee brace. Tenderness was seen around the right patella. She could bend her right knee from 0 degrees to 60 degrees. Extension lag and instability of varus and valgus were not existent. An X-ray showed the FTA was 172 degrees on the right side. The right knee had a TKA(Stryker Scorpion Energy®/fixed surface), and the measurements of component after TKA were almost good. However, the patella had lateral subluxation. A CT image showed the femoral component inserted in internal rotation of 8 degrees from CEA and tibia component inserted in internal rotation of 23 degrees from the left Akagi line. We diagnosed right knee dislocation because of rotation failure of the components. COURSE OF TREATMENT. We replaced implants which were produced by the same company. We replaced the tibial component externally referring to the Akagi's line. On the femur side, we augumented the femur component at the posterolateral and replaced it referring to the CEA. We made a lateral release and used a CCK surface. We did not replace the patella because the surviving patella bone was thin and patella tracking was satisfactory.2 weeks after the operation, she could bend her knee from 0 degrees to 120 degrees and walk with a cane. An X-ray showed the patella was reduced and a CT scan showed the appropriate rotation angle. DISCUSSION. Regarding the treatment of patella dislocation after TKA, when there is malrotation of components, revision is recommended. The definition and the degree of malrotation are still controversial. It was reported that when total internal rotation angle was more than 7 degrees, Revision is recommended. This patient obtained the stability of patella due to the proper rotation angle of components

Optimal management of acute patellar dislocation is still a topic of debate. Although, conventionally it has been managed by non-operative measures, recent literature recommends operative treatment to prevent re-dislocations. Our study recommends that results of non-operative measures comparable to that of operative management. Our study is the retrospective with 46 consecutive patients (47 knees) of first time patellar dislocation managed between 2012 and 2014. The study methodology highlighted upon the etiology, mechanism of injury and other characteristics of first time dislocations and also analysed outcomes of conservative management including re-dislocation rates. The duration of follow up ranged from 1 to 4 years. Average age at first-time dislocation was 23 years (Range 10–62 years). Male:Female ratio was 30:17. Twisting injury was the commonest cause. 1 patient required open reduction but all others relocated spontaneously or had successful closed reduction. Medial Patello-Femoral Ligament injury was frequent associated feature. 11 knees (24%) re-dislocated during follow up. Age was the significant risk factor for re-dislocations. All patients with re-dislocation were less than 30 years old. Maximum redislocations happened between 6 months to 1 year after index dislocation. Skeletal abnormality was the commonest pathology in re-dislocators. Only 4 patients (8.6%) finally required surgical intervention. One patient had persistent knee pain as a complication. Conservative management of primary patellar dislocation is successful in majority of patients. Surgery should be reserved for the carefully selected patients with specific indications

Lateral patellar dislocation is a common cause of acute traumatic haemarthrosis in young active patients, usually occurring during sporting activites. Patients can often be unaware it has occurred. Often magnetic resonance imaging offers the first diagnosis. Most patellar dislocations are treated conservatively with an emphasis on early return to movement. We report on a series of 80 consecutive patients who were diagnosed as having had a transient patellar dislocation by MRI from November 2001 to April 2008 as evidenced by the characteristic countercoup pattern of bone bruising seen on the lateral femoral condyle. In addition to the patellar findings, the images were reviewed with specific reference to the medial collateral ligament, a heretofore undescribed concomitant injury. During the study period, 80 patients (66 males, 14 females) were diagnosed on MRI as having had transient patellar dislocation. The mean age (mean +/− standard deviation) of the cohort was 23.9+/−7.5 years (range:11–60 years). In all but two cases, normal anatomical alignment had been restored. In addition to multiple patellar chondral findings, the condition of the MCL was commented upon in 77 cases (96.3%). Of these, 40 (51.9%) had documented damage to the MCL. These injuries were classified as grade 1 (n=20), grade 1/2 (n=2), grade 2 (n=13), grade 2/3 (n=2) and grade 3 (n=3). Male patients were more likely to have had MCL damage 54.5% vs. 28.6% (p=0.07, Chi-Square). These results serve to highlight the co-existence of MCL injuries with patellar dislocation to a relatively high incidence. This injury should be suspected and examined for in the case of prolonged symptoms after dislocation especially in male patients

Abstract. Introduction. Fractures of the articular surface of the patella or the lateral femoral condyle usually occur following acute dislocation of the patella. This study looked at the radiological and functional outcomes of fixation of osteochondral fractures. Methods. Twenty-nine patients (18 male, 11 female) sustained osteochondral fractures of the knee following patellar dislocation. All patients had detailed radiographic imaging and MRI scan of the knee preoperatively. An arthroscopic assessment was done, followed by fixation using bio-absorbable pins or headless screws either arthroscopically or mini-open arthrotomy. VMO plication or MPFL repair were done if necessary. MRI scan was done at follow-up to assess for healing of the fixed fragment prior to patient discharge. Results. The mean age of the patients was 21 yrs (9–74), 11 had osteochondral fracture of the patella (38%), while 18 were from the lateral femoral condyle (62%). 13 patients needed additional VMO plication. Mean follow up period was 7.7 years (1 to 12 years). As per Tegner activity scale, all patients returned to their pre-injury activity level (Mean score 7) and sports. None of the patients had a further episode of patellar dislocation. Mean postoperative IKDC score was 86.5 (SD 17.3), Kujala was 91.1(SD 15.5) and Tegner- lysholm was 88.7 (SD 14.4). All patients had statistically significant (p < 0.05) improvement. Post-operative MRI scan showed satisfactory union in all cases (100%). Conclusion. It is extremely important to identify this group of injury and treat them early to have satisfactory knee function and avoid long term complications of arthritis

We retrospectively reviewed the operative treatment carried out between 1988 and 1994 of eight patients with habitual patellar dislocation. In four the condition was bilateral. All patients had recurrent dislocation with severe functional disability. The surgical technique involved distal advancement of the patella by complete mobilisation of the patellar tendon, lateral release and advancement of vastus medialis obliquus. The long-term results were assessed radiologically, clinically and functionally using the Lysholm knee score, by an independent observer. The mean age at operation was 10.3 years (7 to 14) with a mean follow-up of 13.5 years (11 to 16). One patient required revision. At the latest follow-up, all patellae were stable and knees functional with a mean Lysholm knee score of 98 points (95 to 100). In those aged younger than ten years at operation there was a statistically significant improvement in the sulcus angle at the latest follow-up (Student’s t-test, p = 0.001). Two patients developed asymptomatic patella infera as a late complication. This technique offers a satisfactory treatment for the immature patient presenting with habitual patellar dislocation associated with patella alta. If performed early, we believe that remodelling of the shallow trochlea may occur, adding intrinsic patellofemoral stability

We evaluated the outcome in a series of patients with recurrent patellar dislocation who had either medial transfer of the tibial tuberosity and lateral release or an isolated lateral release as the primary treatment. The decision to use one or other procedure was based on a pre-operative distance between the tibial tuberosity to the trochlear groove (TTTG) of less than 10 mm to include the tibial tuberosity transfer in addition to the lateral release. Between April 2002 and December 2006, 49 patients (63 knees) underwent one of these procedures. A total of 35 patients (46 knees) was evaluated at a mean of 38 months (13 to 71) post-operatively. Medial transfer of the tibial tuberosity was performed in 33 knees and isolated lateral release in the remaining 13. Evaluation included the International Knee Documentation Committee (IKDC), the Kujala and the Short-form 36 scores. From the tibial tuberosity group 23 knees also underwent radiological examination at follow-up. There were further episodes of patellar dislocation in six of the 46 knees available for review. Further dislocation was noted in five of 33 knees (15.2%) in the tibial tuberosity transfer group and in one of 13 knees (7.7%) in the lateral release group. The mean subjective IKDC score was 80.4 (. sd. 11.6), the mean Kujala score 88 (. sd. 8.2) and the mean objective IKDC score was 79% normal and 21% nearly normal. The mean post-operative TTTG distance in the tibial tuberosity transfer group was 8.9 mm (3.2 to 15.7) compared with the mean pre-operative value of 16.8 mm (12.2 to 24.4)

Introduction: The purpose was to present a new osteotomy technique (trochleoplasty) and its preliminary results for the treatment of femoral trochlear dysplasia with recurrent patellar dislocation. Methods: Between 1990 and 2002, 59 knees of 51 patients (mean age 224 years) with recurrent patellar dislocation due to femoral trochlear dysplasia were treated uniformly at a single institution with a new osteotomy technique developed by the senior author. A distally connected osteochondral flake is released from the dysplastic trochlea and refixed after the osseous trochlear groove has been reconstructed. 44 patients with 50 involved knees returned at a mean follow-up of 37 months (range 6 to 139) for a physical examination, assessment of knee pain and function, radiographic examination of the knee, and in selectived cases for CT scan, MR imaging and follow-up knee arthroscopy. Results: Postoperative complications were limited to hemarthros-1, arthrofibrosis-1, and sudeck‘s disease-1. Postoperatively, no further patellar dislocations were reported. All patients experienced a sensation of significantly improved knee stability resulting in higher levels of activity. Retropatellar pain as found in 34 knees preoperatively was better-24, unchanged-7, worse-6 (3 additional cases) after surgery. Positive apprehension sign, as preoperatively found in all patients, turned negative in all cases. Radiographically, osseous healing of the reconstructed trochlea was noted without evidence of subsequent arthrosis. MRI and knee arthroscopy including histological analysis of osteochondral biopsies did not provide any evidence for osteonecrosis or chondropathia. Conclusion: Recurrent patellar dislocation due to femoral trochlear dysplasia can be treated successfully using the presented technique of trochleoplasty

In 11 paediatric patients (seven girls and four boys, from 12 to 15 years old) with unilateral obligatory patellar dislocation and ligamentous laxity vastus medialis advancement, lateral release, partial patellar ligament transposition and Galeazzi semitendinosus tenodesis was undertaken to stabilise the patella. The diagnostic criterion for ligamentous laxity was based on the Beighton scale. Outcomes were evaluated radiologically and functionally by measurement of the range of knee movement and isokinetic testing. The evaluation also included the Lysholm knee scale. Follow-up studies took place at a mean of 8.1 years (5 to 15) post-operatively. Normal patellar tracking without any recurrence of dislocation was obtained in ten out of 11 patients. Pain related to vigorous activity was reported by nine patients. Compared with the opposite normal side, the isokinetic tests revealed a statistically significant decrease in the maximal torque values for the affected quadriceps muscle (p = 0.003 and p = 0.004), but no difference between the knee flexors (for angular velocities of 60°/s and 180°/s) (p = 0.858 and p = 0.79). The applied surgical technique generally prevents the recurrence of the disorder in children with habitual patellar dislocation and ligamentous laxity. Quadriceps muscle weakness can be expected to occur post-operatively,. Cite this article: Bone Joint J 2015;96-B:129–33

Aims. The aim of this study was to investigate the changes in femoral trochlear morphology following surgical correction of recurrent patellar dislocation associated with trochlear dysplasia in children. Patients and Methods. A total of 23 patients with a mean age of 9.6 years (7 to 11) were included All had bilateral recurrent patellar dislocation associated with femoral trochlear dysplasia. The knee with traumatic dislocation at the time of presentation or that had dislocated most frequently was treated with medial patellar retinacular plasty (Group S). The contralateral knee served as a control and was treated conservatively (Group C). All patients were treated between October 2008 and August 2013. The mean follow-up was 48.7 months (43 to 56). Axial CT scans were undertaken in all patients to assess the trochlear morphological characteristics on a particular axial image which was established at the point with the greatest epicondylar width based on measurements preoperatively and at the final follow-up. Results. Preoperatively, there were no statistically significant differences between the trochlear morphology in the two groups (sulcus angle, p 0.852; trochlear groove depth, p 0.885; lateral trochlear inclination, p 0.676; lateral-to-medial facet ratio, p 0.468; lateral condylar height, p 0.899; medial condylar height, p 0.816). Many radiological parameters of trochlear morphology were significantly different between the two groups at the final follow-up, including well-known parameters, such as the mean sulcus angle (Group S, 146.27° (. sd. 7.18); Group C, 160.61° (. sd. 9.29); p < 0.001), the mean trochlear groove depth (Group S, 6.25 mm (. sd. 0.41); Group C, 3.48 mm (. sd. 0.65); p < 0.001) and the mean lateral trochlear inclination (Group S, 20.99° (. sd. 3.87); Group C, 12.18° (. sd. 1.85); p < 0.001). Lesser known parameters such as the ratio of the lateral to medial trochlear length (Group S, 1.46 (. sd. 0.19); Group C, 2.14 (. sd. 0.42); p < 0.001), which is a measurement of facet asymmetry, and the lateral and medial condylar height were also significantly different between the two groups (p < 0.001). Conclusion. The femoral trochlear morphology can be improved by early (before epiphyseal closure) surgical correction in children with recurrent patellar dislocation associated with femoral trochlear dysplasia. Cite this article: Bone Joint J 2018;100-B:811–21

Background: There are several surgical options for recurrent lateral dislocations of the patella. As the reconstruction of the medial patellofemoral ligament reconstruction (MPFL) has been proven to restore stability, it has become more accepted by surgeons. No study to date has examined the difference in clinical outcome between patients with a primary MPFL reconstruction (group 1) versus MPFL reconstruction in patients with a previously failed patellar stabilizing operations (transposition of tibial tuberosity, trochleoplasty, medial raphy) (group 2). Study type: Prospective cohort study. Methods: 30 patients have been treated with an MPFL reconstruction for episodic patellar dislocation between april 2007 and april 2008. 12 of them already had a patellar stabilizing operation in the history (group 2). The clinical follow up was done by the KOOS and KUJULA scores. Results: For both groups, the KOOS and KUJALA score increased significantly at final follow-up. KOOS pain and ADL subscore had the lowest increase. At final follow-up, the KUJALA and KOOS score were significantly higher for group 1 vs group 2. The net gain for both KOOS and KUJALA was also significantly higher in group 1 compared to group 2. Conclusions: MPFL reconstruction is a viable treatment option for episodic patellar dislocation both in a primary setting as well as in a secondary setting for failed surgery cases. The net clinical gain is nevertheless significantly higher in primary cases

We report a case of a 20-year-old microcephalic patient who suffered from symptomatic patellar dislocation since his early days. His patella was laterally dislocated from full extension to 40° of flexion and would remain subluxated thereafter. His CT-scan revealed excessive ipsilateral femoral neck anteversion (45°) that resulted in substantial internal femoral torsion and subsequently led to patella dislocation. He was treated in one stage with a stepwise procedure, that involved arthroscopic assessment of patellar tracking followed by derotational femoral shaft osteotomy. Tracking was reassessed arthroscopically and although improved was still suboptimal. Therefore an arthroscopic lateral release and an Elmslie-Trillat tibial tubercle transfer were undertaken. This led to very satisfactory patellar tracking. One year postoperatively he had significant functional improvement, no further episodes of patellar dislocation and a ROM of 0–110°. His Lysholm score improved from 45 to 88, his Tegner activity scale from 2 to 4 and his Knee Outcome Score from 38/80 to 70/80. This complex case highlights excessive femoral neck anteversion as a causative factor for patella dislocation. A combination of proximal and distal bony realignment procedures is proposed and the role of arthroscopy is emphasised

Background. Primary dislocation of the patella is a common acute knee disorder in children, adolescents and young adults. While primary dislocation of the patella has traditionally been treated non-operatively, primary operative repair of the medial patella-stabilizing soft tissues has been popularized more recently and thought to reduce the risk of dislocation. However, several studies have shown substantial rates of redislocation with longer follow-up time, irrespective of treatment. The purpose of this systematic review was to compare operative and non-operative treatment for primary dislocation of the patella, regarding redislocation rates and symptoms. Methods. Based on a systematic literature search of the medical literature from 1950 to 2010, three randomized and two quasi-randomized controlled clinical trials comparing surgical stabilization with non-operative treatment for patients with primary patellar dislocation were selected. The Risk of Bias Tool (Cochrane Handbook, 2008) was used to assess the quality of the studies included. Study results were pooled using the fixed-effects and random-effects models with mean differences and risk ratios for continuous and dichotomous variables, respectively. Heterogeneity across studies was assessed with Q test and I-square statistic. A sensitivity analysis was performed by assessing the change on effect size by eliminating each single trial. Results. In total, 341 patients from 5 trials were included. 158 patients were treated non-operatively and 183 patients were treated operatively. For primary outcome of patellar redislocation, while significant heterogeneity was found using the random-effects model, no significant difference was observed between the treatment groups (pooled RR=1.36, 95% CI 0.8–2.31, p=0.25). No significant difference was observed between the treatment groups (pooled RR=1.36, 95% CI0.8–2.31, p=0.25). No significant differences were found between both groups for symptoms ofinstability (RR of 1.24, 95% CI 0.96–1.59, p=0.10), Kujala knee score (−5.66, 95% CI −15.51 −4.19, p=0.26) or requirement for later surgery (RR=0.92, CI 0.61–1.39, p=0.69). Conclusions. This meta-analysis found no differences in patellar redislocation rate, patient reported instability symptoms, Kujala Knee score and rate of later surgery after initial treatment, between operative and non-operative treatment of primary patellar dislocation. Level of evidence. Level II

Approximately 700 TKRs (Total Knee Arthroplasty) were performed in our department from 1992–2000. In 13 cases, patellar dislocation occurred post-operation - 12 with no trauma and one following a fall and trauma to the medial aspect of the knee. Dislocation occurred from 2 months following the operation until 1 year postoperative (average 4.5 months). None of the patients had malalignment of the components. The average femorotibial angle was 5° (range 8° valgus to 3° varus). No patient had preoperative valgus deformity. Postoperative range of motion was 105° (range 90–125°). All dislocations were treated by operative lateral relapse and medial capsular implication followed by 6 weeks of immobilization with a brace in full extension and then physiotherapy, range of motion, patellar taping and Vastus medialis strengthening. The patella stabilized in 11 cases following the operation. In 2 cases, dislocation recurred following the operation and they were operated on again where medialization of the tibial tubercle was performed. Both cases stabilized following the second operation. One case developed a stress fracture of the tibia at the end of the tubercle osteotomy which healed conservatively. All dislocations occurred in the IBII prosthesis. During the past 3 years since using the PFC Sigma and Legacy prosthesis, we have had no dislocations of the patella, probably for the following reasons:. Use of the mid vastus exposure. Geometry of the prosthesis. In only 10% of the replacements, patellar resurfacing was performed

Magnetic resonance imaging was used to analyse the patellofemoral relationships during the first 30 degrees of knee flexion in women with recurrent patellar dislocation. The patellofemoral joints were imaged both sagittally and axially with the knee flexed 0 degrees, 10 degrees, 20 degrees, and 30 degrees. At the beginning of knee flexion the sulcus angle was greater than in unaffected women, the lateral patellofemoral angle was smaller, the patella displaced further laterally, tilted more laterally and the congruence angle was directed more laterally. At 30 degrees of knee flexion these differences were less marked than at 0 degree to 10 degrees. Logistic regression analysis showed that the sulcus angle at 10 degrees of knee flexion was the most diagnostic feature, indicating that there is an anatomical predisposition to recurrent dislocation and that pathological patellar tracking starts from the beginning of flexion. Traditional sunrise radiographic films taken at 25 degrees to 30 degrees knee flexion clearly miss diagnostically important information

The assessment of the long –term outcome (5 years) of patients treated with arthroscopic stabilization for acute traumatic patellar dislocation. From September 2004 until April 2009 we treated 29 patients (25 male, 4 female) with a median age of 18 years (range 14–23 years), two of them had suffered from traumatic dislocation of the patella of the other knee joint in the past. The median range from injury to our surgical intervention was 20 days (7–29 days). The return in sporting activities, the possible redislocation or joint instability and the subjective assessment of the symptoms of the patients, were evaluated in a 5 years follow-up. After 5 years, 23 patients (20 males, 3 females), were re-evaluated. After the arthroscopic medial retinacular repair all the patients return to sporting activities. All the patients presented chondral lesions at the medial facet of the patella and to the lateral femoral condyle and hemarthrosis too. The functional outcomes were evaluated with Kujala scoring scale, with Visual analog scale and Tenger scale the range of results was good. The acute arthroscopic repair of the medial retinacular ligaments, protects the patient from redislocation or subluxation, allows the evaluation and stabilisation of the chondral lesions, the removal of free chondral bodies, as well as the evaluation of the possible damage to the menisci or ACL, PCL ligaments. All the patients returned to normal sporting activity avoiding further injury, or the development of osteoarthritis of the knee joint