Anatomical Characteristics and Potential Gene Mutation Sites of a Familial Recurrent Patellar Dislocation

Background Recurrent patellar dislocation is the result of anatomical alignment and imbalance of restraint of bone and soft tissue. To 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 exon sequencing in 4 patients and 4 healthy subjects, so as to provide theoretical basis for the pathogenesis of this disease. Methods The data related to patella dislocation were measured by imaging data. The peripheral blood DNA of related family members was extracted for full exon sequencing, and then the sequencing results were compared with the human database. By filtering out synonymous mutations and high-frequency mutations, and then integrating single nucleotide non-synonymous mutations of family members, disease-causing genes were found. Results All patients in this family have different degree 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:p.Glu135Gly/c.404A>G),COL1A1(NM_000088.3:p.Ala1256 Thr/c.3766G>A),GNPAT(NM_014236.3:p.Asp519Gly/c1556A>G),NANS(NM_018946.3:p.Glu68Asp/c.204G>C),SLC26A2(NM_000112.3:p.Thr689Ser/c.2065A>T) are not synonymous mutations (MISSENSE). Through Sanger sequencing, HOXB9 and SLC26A2 genes were found to be the pathogenic genes of this family with recurrent patella dislocation. Conclusions The anatomical structure of the knee joint of patients with recurrent patellar dislocation in this family is obviously abnormal. HOXB9 mutation may be the high frequency pathogenic gene of recurrent patella dislocation in this family, while COL1A1, GNPAT, NAans, SLC26A2 gene may be the sporadical pathogenic gene.

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.

Chondral and Soft Tissue Injuries Associated to Acute Patellar Dislocation: A Systematic Review

Introduction: Chondral and soft tissue injuries can be associated with first time patellar dislocation, but it is unclear how common they are, and which tissues are affected. A systematic review of the literature was performed to investigate the frequency, location, and extent of chondral and medial patellofemoral ligament (MPFL) injuries in patients following first time patellar dislocation. Methods: This systematic review was conducted according to the PRISMA guidelines. PubMed, Google Scholar, Embase, and Web of Science databases were accessed in November 2021. All the published clinical studies reporting the frequency, location, and extent of soft tissue lesions following first time patellar dislocation were accessed. Studies reporting data on habitual, congenital, or recurrent patellofemoral instability were excluded. Results: Data from 42 articles (2254 patients, mean age 21.6 ± 7.3 years) were retrieved. Ninety-eight percent of patients who experienced first time patellar dislocation demonstrated MPFL rupture at MRI. Forty-eight percent of MPFL ruptures were located at the patellar side, 34% at the femoral insertion site, and 18% in the midportion. Eighty-five percent of patients showed signs of patellar chondral damage at MRI, and trochlear chondral injuries were evidenced in 47% of patients. Intra-articular loose bodies were observed in 11.5% of patients. At arthroscopy, the medial facet and the crest of the patella more commonly exhibited chondral lesions than the lateral facet and femoral trochlea. Conclusions: Most patients suffer chondral damage and MPFL tears following after a first time patellar dislocation.