Case study 2: John
- John’s parents took him to the doctor because he had been limping for a week and had complained of pain in his right knee1
- John did not have any recent trauma, fever, cough, rash, abdominal pain, diarrhea, numbness in the extremities or other joint pain
- John complained of tenderness in his groin region when he flexed his right hip
- John’s physician ordered the following laboratory tests: Complete blood count, serum electrolytes, calcium, magnesium and phosphorus levels, erythrocyte sedimentation rate, thyroid stimulating hormone, thyroxine, and growth hormone. All were normal.
Patient file
Table 1: Patient characteristics and observations from medical examination
Age | 6 years |
Vital signs | Normal |
Height | 25th percentile |
Weight | <5th percentile |
Anterior drawer test | Negative |
McMurray test | Negative |
Trendelenburg test | Positive |
X-ray findings

- How do you interpret these findings?
- When examining these test results, would you consider a diagnosis of MPS?
Figure 1: Radiograph of the hip and femur showing necrosis of the femoral head.1
Disease background
- John’s hip dysplasia is characteristic of a number of diseases, including MPS, Legg–Calvé–Perthes disease (LCPD), and various musculoskeletal disorders
- LCPD is an often self-limited, pediatric hip disorder mainly affecting boys. It is an idiopathic condition characterized by necrosis of the growing femoral head due to an interruption in blood flow to the capital femoral epiphysis. In most cases, only one hip is involved1
- The disease usually presents between the ages of 5 and 7 years old with a slowly developing limp that may be accompanied by groin, thigh or knee pain. Patients often have limited abduction and difficulty medially rotating the affected leg1
- Although the cause of LCPD is not known, it has a number of well-defined stages. Initially, loss of bone mass due to necrosis results in deformity of the ball of the femur and hip socket surface. Patients may also sustain fractures of the subchondral cortical bone, often as a result of normal physical activity. This leads to fragmentation and reabsorption of bone. As the bone is reabsorbed, it is gradually replaced with new bone tissue2
Interpretation and diagnosis
- The symptoms experienced by John are consistent with LCPD. Patients typically present with hip or groin pain, mild or intermittent pain in the thigh or knee, and a limping gait1
- Classic radiographic findings of LCPD include fragmentation and sclerosis of the capital femoral epiphyses
- Radiography is used for diagnosis and staging of LCPD
- John’s X-ray shows necrosis of the femoral heads. In comparison, MPS patients show enlarged diaphyses, underdeveloped epiphyseal centers and irregular metaphyseal appearance in the long bones2
- John also presented with unilateral hip involvement, which is common in patients with LCPD3. Bilateral hip involvement is seen in only 5–10% of patients and generally in such cases the joints are involved successively, rather than simultaneously3,4. In patients with MPS, however, hip dysplasia is usually bilateral
- As the osteonecrosis in LCPD is due to poor blood supply, a dynamic bone scan could help to establish presence of vascular abnormalities that may be indicative of LCPD rather than MPS5
- John should also be examined for other signs of dysostosis multiplex to exclude the presence of MPS
MPS has a similar radiological pattern of the hip joints to LCPD. Sometimes MPS can be misdiagnosed as LCPD. All patients with a diagnosis of LCPD, including adults, should be examined for other signs of dysostosis multiplex to exclude the presence of MPS.
- Rodrigues RG. Postgrad Med J 2003;79:179.
- Morini SR, et al. J Pediatr Orthop B 2010;19:313–317.
- Catterall A. J Bone Joint Surg 1971;53B:37–53.
- Wenger DR and Pandya NK. J Pediatr Orthop 2011;31:S130–S136.
- Gandsman EJ and McCullough RW. Int J Rad Appl Instrum B 1990;17:533–541.