E. Leone1, S. Davenport1, C. Robertson2, M. Laurà3, M.M. Reilly3, G. Ramdharry3
1Physiotherapy Group, UCL Great Ormond Street Institute of Child Health, London, United Kingdom, 2Wimbledon Clinics, Parkside Hospital, London, United Kingdom, 3Queen Square Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
Background: Patellofemoral dislocation is commonly encountered in clinical practice among people living with Charcot-Marie-Tooth disease (CMT). Despite the well-recognised association between specific physical characteristics and the occurrence of patellofemoral dislocation, the frequency and the risk factors for patellofemoral dislocation in adults with CMT are currently unknown. Therefore, this study aimed to investigate the incidence and the risk factors for patellofemoral dislocation in adults with CMT.
Purpose: The primary aim of this study was to establish the incidence of patellofemoral dislocation in adults living with CMT. The secondary aim of this study was to explore the risk factors that predispose people with CMT to experience patellofemoral dislocation.
Methods: A cross-sectional, observational study was conducted in a cohort of people with different subtypes of CMT. Adults with CMT attending their outpatient clinics at a specialist neuromuscular centre in the United Kingdom were invited to undergo a patellofemoral evaluation. A physical examination of the knee joint was conducted and a series of questions regarding the history of any patellofemoral dislocation were asked.
Results: Among 31 individuals with CMT, the incidence of patellofemoral dislocation was 32.3%. Patellar dislocation was associated with a CMT-1A sub-type (p=0.013) and younger age at disease onset (p=0.004). Patella alta (OR, 9.0, 95% CI: 2.4 – 34.0; p=0.001), J-sign (OR, 5.4, 95% CI: 1.3 – 21.7; p=0.017), lateral patellar glide (OR, 17.3, 95% CI: 2.1 – 142.8; p=0.001), generalised joint hypermobility (OR, 8.3, 95% CI: 1.6 – 42.1; p=0.012) and knee flexor muscle weakness (p=0.012) were all associated with an increased risk of patellofemoral dislocation. A pronated foot posture was associated with a weak but not-significant increase in risk of patellar dislocation (p=0.163). Patella alta and age of onset were also independent predictors of patellofemoral dislocation (p=0.028 and p=0.024, respectively).
Conclusion(s): Patellofemoral dislocation was common in this cohort of adults with CMT and was associated with multiple risk factors. The identified predisposing characteristics may be addressed by clinicians through preventive, supportive and corrective measures.
Implications: Knowledge of the risk factors may offer clinicians the opportunity to provide those people identified to be at risk for patellar dislocation with individually tailored preventive, supportive and corrective interventions, thereby reducing the occurrence of patellofemoral dislocation episodes and impacting on the disease burden and quality of life of these individuals. A large prospective observational study is needed to more fully understand the incidence and the risk factors for patellar dislocation in this population. For this purpose, the data collection for the current study is still ongoing. A case control, assessor-blinded, study using MRI images would be useful to assess the anatomic risk factors in people with CMT with a prior history of dislocation and control group of individuals with CMT without such a history. This would allow clinicians to objectively assess the risk factors and to explore the correlation between clinical measures and radiological measurements of patellar dislocation.
Funding, acknowledgements: The authors received no specific funding for this work.
Keywords: Patellofemoral dislocation, Incidence, Charcot-Marie-Tooth disease (CMT)
Topic: Musculoskeletal: lower limb
Did this work require ethics approval? Yes
Institution: NHS England
Committee: HSC REC A
Ethics number: 19/NI/0031
All authors, affiliations and abstracts have been published as submitted.
