From Wheelchair to Walking: A Milestone in the Surgical Management of SEMD-JL3

Rare skeletal dysplasias often present clinicians with difficult management decisions because evidence-based treatment recommendations are scarce. Spondyloepimetaphyseal dysplasia with joint laxity type 3 (SEMD-JL3), caused by pathogenic EXOC6B variants, is among the rarest of these disorders, with fewer than 20 cases reported worldwide. Patients typically develop generalized joint laxity, recurrent dislocations, progressive skeletal deformities, chronic pain, and severe loss of mobility from childhood.

In this case report, the authors describe a 16-year-old Saudi Arabian girl with genetically confirmed SEMD-JL3 who had never achieved independent ambulation and had become wheelchair-dependent because of severe bilateral hip dysplasia, advanced knee degeneration, valgus deformity, and fixed contractures. Whole-genome sequencing identified a pathogenic homozygous EXOC6B frameshift mutation, establishing the diagnosis and guiding multidisciplinary management.

Rather than accepting lifelong disability, the treating team developed a carefully staged reconstructive strategy. Bilateral total hip arthroplasties were performed six months apart to restore hip stability, reduce pain, and improve sitting balance. After rehabilitation and recovery, bilateral total knee arthroplasties were undertaken to correct deformity and restore gait. The sequence of surgery was intentional, allowing progressive functional recovery while minimizing biomechanical challenges associated with this complex skeletal dysplasia.

The clinical outcome was remarkable. Pain scores fell substantially, sitting tolerance improved, and intensive rehabilitation ultimately enabled the patient to progress from complete wheelchair dependence to independent ambulation. At one-year follow-up after the final knee replacement, implants remained stable clinically and radiographically while the patient demonstrated greatly improved independence and quality of life.

Beyond its successful outcome, this report expands the limited literature on surgical management of SEMD-JL3. Previous publications have focused primarily on genetic diagnosis and phenotypic characterization, whereas this report provides practical operative and rehabilitation experience that may guide future treatment of similarly affected patients. It also illustrates the importance of multidisciplinary collaboration among orthopedic surgeons, geneticists, rehabilitation specialists, and physical therapists when caring for patients with rare skeletal disorders.

For orthopedic surgeons and clinicians caring for patients with rare musculoskeletal diseases, this case demonstrates that even profound functional impairment should not automatically preclude consideration of reconstructive surgery. Careful patient selection, meticulous surgical planning, staged intervention, and structured rehabilitation may dramatically improve mobility and quality of life, even in conditions where published experience is exceptionally limited.

Clinical Take-Home Message

Patients with severe EXOC6B-related SEMD-JL3 should not be considered beyond reconstructive treatment solely because of disease rarity. Individualized staged total hip and knee arthroplasty, combined with multidisciplinary rehabilitation, can transform functional outcomes and restore meaningful independence in carefully selected patients.

Journal of Medical Case Reports is the world's first international, PubMed-listed medical journal devoted to publishing case reports from all medical disciplines and will consider any original case report that expands the field of general medical knowledge, and original research relating to case reports. The journal is open access and strongly endorses the CARE guidelines for case reports, requiring authors to submit populated CARE checklists with submissions to improve transparency in reporting.