Joint And Bone Manifestations Of Mucopolysaccharidoses (MPS)

Dr. Borgo begins by explaining the pathophysiology of MPS, where glycosaminoglycan (GAG) accumulation impairs the function of chondrocytes and alters enchondral ossification from early fetal development. He shows histological evidence of disorganized growth plates and emphasizes that skeletal abnormalities often start prenatally. Although enzyme replacement therapy (ERT) and bone marrow transplantation can slow progression and improve growth, they offer limited correction of established deformities.

The session outlines major orthopedic features across MPS types, including short stature, joint stiffness, delayed ossification, and progressive bone dysplasia. He highlights three critical red flags for MPS: thoracolumbar kyphosis in early childhood, trigger fingers (other than the thumb), and pediatric carpal tunnel syndrome—rare findings in healthy children.

Dr. Borgo systematically reviews musculoskeletal complications by body region:

• Spine: Thoracolumbar kyphosis and cervical instability may require bracing or surgical intervention, especially if signs of myelopathy emerge. He notes that surgical timing (ages 5–13) is key to avoiding implant failure or uncorrectable deformity.
• Upper limbs: Stiffness, limited abduction, and carpal tunnel syndrome affect many patients. Surgery (e.g., open carpal tunnel release or pulley releases for trigger fingers) can improve function, but thickened ligaments and nerve involvement complicate procedures.
• Hips: Hip dysplasia, loss of femoral head sphericity, and subluxation commonly progress in MPS I and II. While femoral and pelvic osteotomies can realign the hip, acetabular remodeling is poor, and long-term results are limited. Many patients eventually require total hip replacement in young adulthood, which is technically challenging due to size constraints and poor bone quality.
• Lower limbs: Valgus deformities of the knees and ankles can be corrected early with hemiepiphysiodesis. Delays reduce surgical effectiveness. Arthroplasty may be needed for arthritis in adulthood.

Dr. Borgo concludes by urging pediatricians and orthopedic surgeons to be vigilant for early orthopedic signs of MPS. Prompt referral, timely surgical interventions, and use of local/regional anesthesia where possible can improve long-term outcomes and reduce complications.

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