Patellofemoral dysplasia is a major predisposing factor for instability of the patellofemoral joint. However, there is no consensus as to whether patellofemoral dysplasia is genetic in origin, caused by imbalanced forces producing maltracking and remodelling of the trochlea during infancy and growth, or due to other unknown and unexplored factors.The biomechanical effects of patellofemoral dysplasia on patellar stability and on surgical procedures have not been fully investigated. Also, different anatomical and demographic risk factors have been suggested, in an attempt to identify the recurrent dislocators. Therefore, a comprehensive evaluation of all the radiographic, MRI and CT parameters can help the clinician to assess patients with primary and recurrent patellar dislocation and guide management.Patellofemoral dysplasia still represents an extremely challenging condition to manage. Its controversial aetiology and its complex biomechanical behaviour continue to pose more questions than answers to the research community, which reflects the lack of universally accepted guidelines for the correct treatment. However, due to the complexity of this condition, an extremely personalised approach should be reserved for each patient, in considering and addressing the anatomical abnormalities responsible for the symptoms.Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160081. Originally published online at www.efortopenreviews.org

Background: Meniscal repair has become the treatment of choice for meniscal tears, especially in the subset of bucket-handle meniscal tears (BHMTs). However, a comprehensive estimate of the corresponding failure rate is not available, thus maintaining doubts about the healing potential of these tears. Furthermore, a wide range of factors to predict high failure rates have been reported but with conflicting evidence. Purpose: To determine the failure rate after arthroscopic repair of BHMTs as reported in the literature, compare this with the failure rate of simple meniscal tears extracted from the same studies, and analyze the influence of factors previously reported to be predictive of meniscal repair failure. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: A systematic search was conducted by 2 independent reviewers using principal bibliographic databases (PubMed, Scopus, Cochrane Library, and EMBASE). After a stepwise exclusion process, 38 articles met the inclusion criteria. Failure rate data were analyzed with a random-effects proportional meta-analysis (weighted for individual study size), and forest plots were constructed to determine any statistically significant differences between BHMTs versus simple tears (longitudinal, radial, or horizontal), medial versus lateral BHMTs, isolated procedures versus repairs with concomitant anterior cruciate ligament reconstruction, and tears in red-red versus red-white zones. Moreover, a meta-regression analysis was conducted to evaluate the effect of patient age and sex, suture technique (in-out or all-inside), time from injury to surgery, mean number of stitches, and length of follow-up on failure rates. Results: The pooled failure rate was 14.8% (95% CI, 11.3%-18.3%; I2 = 77.2%). A total of 17 studies provided failure rates of both BHMT repairs (46/311 repairs) and simple tear repairs (54/546 repairs), demonstrating a significantly higher failure rate for BHMT repairs (risk ratio [RR] = 1.50; 95% CI, 1.05-2.15; I2 = 0%; P = .03). Medial BHMT repairs (RR = 1.94; 95% CI, 1.25-3.01; I2 = 0%; P = .003) and isolated repairs (RR = 1.77; 95% CI, 1.15-2.72; I2 = 0%; P = .009) had statistically higher risk of failure, but no statistically significant difference was found between tears in red-red versus red-white zones. Among the other factors evaluated with meta-regression, only the mean number of stitches showed a statistically significant effect on failure rates. Conclusion: Based on the currently available literature, this systematic review provides a reasonably comprehensive analysis of failure rate after arthroscopic BHMT repair; failure is estimated to occur in 14.8% of cases. Medial tears and isolated repairs were the 2 major predictors of failure.