Primary hypertrophic osteoarthropathy and bilateral transient lateral patellar dislocation in an adolescent

This case report is of the index case of bilateral transient patellar dislocation in a patient with primary hypertrophic osteoarthropathy. Primary hypertrophic osteoarthropathy is a rare complex disorder with variable presentation and thus frequently delayed diagnosis. Notably this disease has multiple skeletal manifestations and, of relevance to this case, a proportion of patients suffer from osteitis. Our patient had serial imaging of the knee joints demonstrating osteitis and associated alteration of the femoral trochlea morphology, predisposing to bilateral transient lateral patellar dislocation. The patient’s clinical presentation, diagnosis and management are discussed. Classification of the disease and its diagnostic parameters are summarised along with key imaging features amongst various imaging modalities.

Visualization of osteochondral fragments in the cavity of the knee joint in case of patellar dislocation in children

The objective was to assess the capabilities of MRI and CT in visualizing free bone and cartilage fragments in the knee cavity after lateral dislocation of the patella. Materials and methods. CT and MRI were performed in 220 patients, including 127 girls and 93 boys aged 12 to 18 years (mean age 14.5 years), with acute lateral patellar dislocation. Results. Lateral dislocation of the patella in 25% of cases led to the appearance of osteochondral fragments. CT scan revealed and confirmed osteochondral fragments surgery in 55 people (100%), MRI scan - in 50 people (90%). The sites of the detachment of the osteochondral fragments were: a medial facet of the patella in 22 (38.8%), the outer edge of femur lateral condyle in 33 (58.2%), t patella and lateral condyle of the femur in 2 patients (3%). Free cartilage fragments not detected by CT were detected by MRI in 2 patients. Conclusion. Patellar dislocation is an injury that is likely to require surgery. The volume of osteochondral and soft tissue lesions can be established with the maximum degree of probability by MRI while detecting small osteochondral fragments is most reliable with CT. Combining these two observation methods provides the complete possible information about the extent of damage, which allows timely resolution of treatment tactics.

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

Background Lateral 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. Methods A 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. Results Fifteen 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. Conclusion The 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 registration ClinicalTrials.govNCT03798483, registered on January 10, 2019

First-Time Acute Lateral Patellar Dislocation in Children and Adolescents: What About Unaffected Knee Patellofemoral Joint Anatomic Abnormalities?

Background and Objectives: Acute lateral patellar dislocation (LPD) is the most common acute knee disorder in children and adolescents, and may lead to functional disability. The purpose of this study was to identify key differences and correlations of the patellofemoral joint (PFJ) morphology between intact and contralateral injured knees in a first-time traumatic LPD population aged under 18 years. Materials and Methods: The data were gathered prospectively from a cohort of 58 patients (35 girls and 23 boys). The prevalence and combined prevalence of patella alta (PA) and trochlear dysplasia (TD) in both knees of patients were evaluated using X-ray by two radiologists. Results: The PFJ of patients’ intact knees had a lower rate of TD (1.72% vs. 5.2%) and a less common combination of PA with shallow femoral sulcus (SFS) (22.4% vs. 44.8%) but more frequent PA (62.1% vs. 41.4%) compared with their injured knees. We noted statistically significant positive correlations (SSPCs) between the femoral sulcus angle (FSA) and PA in patients with intact (r = 0.37; p < 0.005) and contralateral injured knees (r = 0.33; p < 0.05). Conclusion: There were SSPCs between the FSA and PA in both gender and age groups of patients with intact and contralateral injured knees. The SSPCs between the FSA and PA of intact knees were higher in the patients with a more dysplastic PFJ anatomy (PA and TD) of the injured knees as compared to patients with only PA of the injured knees.

Patella dislocations and patellofemoral instability: a current concepts review

ABSTRACT Lateral patellar dislocation affects young, active patients with an incidence rate of 5.8 per 100 000. The management of first episode dislocations is non-surgical in the majority of cases, unless associated pathology dictates surgical intervention. Approximately 40% of cases that are treated non-surgically will develop recurrent patellofemoral instability. Evidence supports surgical intervention in these cases; however, the best approach is debatable. Most research and consensus statements agree that medial patellofemoral ligament reconstruction (MPFLR) should be performed in most cases. Additional procedures can be used 'a la carte' according to certain conditions or pathology. A tibial tubercle osteotomy (TTO) is usually indicated in patients with maltracking and/or patella alta, but the direction and degree of correction must be carefully considered. Trochleoplasty is technically demanding and should be reserved for a select few patients with severe trochlear dysplasia. It should be performed by an experienced knee surgeon due to the high risk of inadvertent complications. Level of evidence: Level 5 Keywords: patellofemoral instability, patellar dislocation