Dyschondrosteosis is a syndrome characterized by mesomelic dwarfism, Madelung's deformity, and an autosomal dominant mode of inheritance. The syndrome has few severe orthopedic manifestations. Occasionally, the wrist deformity requires surgical treatment. Presented here is a case in which the only symptomatic complaint was bilateral recurrent patellar dislocations, a finding that has not been previously reported in this syndrome.
A 20-year-old woman was referred to the authors' clinic with a diagnosis of patella dislocations. The dislocations occurred when her knees were brought to full extension. The dislocations were painful, and her symptoms had become intolerable during the previous 2 years. The symptoms were exacerbated with prolonged standing.
Physical examination revealed a shortstatured woman (147 cm) and obvious shortening of the extremities in relation to the trunk. The shortening was of a mesomelic type with shortened tibias and forearms.
The upper extremities lacked 10° of extension at the elbows. There was 15° lack of supination. Pronation was normal. Pain-free full range of motion at the wrists was demonstrated. The ulnar heads were prominent, but no evidence of distal radioulnar joint instability was demon strated.
Examination of the spine was normal.
The lower extremities were in valgus alignment with laterally displaced tibial tubercles. Quadriceps angles measured 20° bilaterally. The range of motion of both knees was 0° to 110°. As the right knee was brought to 30° short of full extension, the patella dislocated laterally with a "bayonet" -type motion. The left patella dislocated less dramatically at the same degree of extension. Patellofemoral crepitance was noted with tenderness on both medial and lateral facets of the patella. The vastus medialus oblique muscle was poorly defined on either leg.
Radiographic evaluation of the left forearm showed a sloping distal radioulnar joint with early fusion of the ulnar side of the distal radial physis. Dorsal and lateral bowing of the ulna was present. These findings were consistent with a diagnosis of Madelung's deformity. The same findings were present on the right but to a less severe degree (Fig I ). The forearms were foreshortened.
Fig 1 : AP radiograph of the right forearm showing Madelung's deformity.
The lower extremities on full-length standing radiographs revealed valgus alignment at the knees with a mechanical axis of 3° valgus on the right and 10° valgus on the left (Fig 2). Sunrise views showed a flattened sulci bilaterally (Fig 3). The patella tilt, however, was normal at 45° of flexion.
A computerized tomography (CT) scan was done with the knees held in full extension. This revealed hypoplastic lateral femoral condyles with frank dislocation of both patellae (Fig 4). The scan was repeated at 45° of flexion. Both patellae were reduced, but the flattened nature of the lateral condyles was still evident in these views.
Dyschondrosteosis was first described by Leri and Weill.1 Their patients had mesomelic dwarfing and Madelung's deformity of the wrists. Since that time, several other articles have been published describing patients with these same findings.2-5
Manifestations of this syndrome include mesomelic dwarfism often not recognized until adolescence. There is a mild reduction in skeletal height (135 cm to 150 cm) at adulthood attributable to the shortened lower extremities.6 The wrist deformity has been described as an early fusion of the ulnar side of the distal radial physis with a sloping distal radioulnar joint; dorsal subluxation of the ulna with dorsal and lateral bowing of the radius is also found. These findings are consistent with a classic Madelung's deformity. On occasion, either radioulnar shortening of an equal degree or predominantly radial shortening has been described.2
Symptomatic lower extremity findings were only mentioned in one paper.2 Two patients were described with tibiofibular disproportion leading to genu varum. One of these patients who was skeletally immature at presentation was treated with tibia lengthening and fibular epiphysiodesis. The other older patient declined treatment. No previous patient has been described with the problem of patellar dislocation.
Fig 2: Standing AP full-length leg radiograph showing a mechanical axis of 3° valgus on the right and 1 0° valgus on the left.
Fig 4: Computerized tomography scan with the knees in full extension showed flattened sulci, hypoplastic lateral femoral condyles, and lateral displacement of both patellae.
Fig 3: Sunrise views in 20° of flexion show a normal lateral patella femoral angle reflecting normal patella tilt. The sulcus angles (not diagrammed here) measured 1 50° bilaterally.
Fig 5: Lateral radiograph of paternal grandfather showing dorsally subluxed distal ulna with degenerative changes.
The patient presented in this report was felt to be of normal stature by her family and was referred only after her patella dislocation became symptomatic. The pedigree of this patient was sketchy, but examinations of her paternal grandfather showed bilateral dorsally subluxed ulnas at the wrists with marked degenerative changes on radiograph (Fig 5).
The subluxing or dislocating patella femoral joint has received much attention in recent orthopedic literature. Many factors contribute to this condition, including a history of violent trauma, altered mechanical alignment, anatomical variations, and generalized ligamentous laxity.7 This patient had both alignment (genu valgum) and anatomical (hypoplastic femoral condyles) factors contributing to her problem. Although some cases of patella femoral subluxation are amenable to surgery, this case was not felt to be due to the above-mentioned factors. A trial of physical therapy and non-steroidal medication decreased her symptoms with no changes in her physical examination. Surgery may be considered in the future if her symptoms increase.
1. Leri A, Weilt J. Une affectione congenitable et symmetrique du development asseux: Ia dyschondrosteo.se. Bull Sot: Med Hisp. 1929; 53:1491.
2. Dawe C, Wynne-Davies R. Fulford GE. A clinical variation in dyschondrosteosis: a report on 13 individuals in 8 tamilies. J Bone Joint Surg. 1982: 64B:377-381.
3. Espiritu C, Chen H. Woolley PV. Mesomelic dwarfism as the homozygous expression of dyschondrosteosis. Am J Dis Child. 1975; 129:375-377.
4. Fryns JP, Vanden Berghen H. Langer type of mesomelic dwarfism as the possible homozygous expression of dyschondrosteosis. Hum Genet. 1979; 46:21-27.
5. Herdman RC. Langer LO, Jr, Good RA. Dyschondrosteosis, the most common cause of Madelung's deformity. J Pediatr. 1966:68:432-441.
6. Basxett G, Scott C. Dyschondrosteosis. In: Morrissy RT, ed. Pediatric Orthopaedics. Philadelphia. Pa: JB Lippincott; 1990; 1:118-119.
7. Crenshaw AH. ed. Campbell's Operative Orthopedics. Sl Louis. Mo: CV Mosby; 1987: 3.