BLOUNT'S DISEASE

STEVEN R. BOYEA, M.D., Resident, Orthopaedic Surgery

J. RICHARD BOWEN, M.D., Chief, Orthopaedic Surgery

June 10, 1996

CLINICAL CASE PRESENTATION

ORTHOPAEDIC DEPARTMENT

THE ALFRED I. DUPONT INSTITUTE

WILMINGTON, DELAWARE

CASE HISTORY:

History: The patient is a 14 + 6 year old black male with a one year history of progressively worsening left knee pain. He states that the pain began in both knees and was intermittent, Tylenol helped alleviate the pain. Over the past 6 months the pain is more isolated to the left knee and has become constant in nature. Within the last 2 weeks the constant pain has become bad enough to limit his activities. He is unable to attend school or walk more than several hundred feet because of the pain. The pain is now affecting his sleep. He does get some relief with rest and elevation of the knee. The pain also limits his motion in that knee. He denies any trauma to the knee and has no other medical problems. He is not taking any medications. There is no family history of leg deformities.

Physical Exam: The adolescent is a morbidly obese 14 + 6 year old black male. His extremity exam reveals an asymmetric pelvis with the right being elevated. There is a leg length inequality with the left leg being about 3.5 cm shorter than the right. He also demonstrates a significant proximal tibia vara of about 35o. There was tenderness to palpation over the medial proximal metaphysis with some mild medial joint line tenderness. The knee demonstrated mild medial laxity on valgus stress. He does not demonstrate any anterior or posterior laxity or instability. There is knee flexion from 0-120o with some tenderness. Hip and ankle show full range of motion and hi is neurovascularly intact. Strength is 5/5 in all muscle groups.

Radiographs: AP/Lateral of left knee from September of 1995 demonstrate a mild varus deformity with an estimated metaphyseal/diaphyseal angle of 8o. There is also evidence of widening of the medial 1/3 of the proximal tibial physis . The AP of the left knee in May of 1996 shows worsening of the varus deformity with a metaphyseal/diaphyseal angle of 14o. There is increased widening of the medial proximal tibial physis with evidence of sclerosis. The scanogram demonstrated a 4 cm leg length discrepancy, with the left shorter than the right . There is no abnormality in the hip or femur.

Assessment:
Treatment:

TIBIA VARA

Background:
  1. First described by Erlander in 1922.
  2. Blount presented 13 cases and reviewed the literature of another 15 cases in 1937 delineating between the different types, adolescent vs. infantile.
  3. Langenskiold classified the six progressive radiographic stages in 1952.
  4. Definition: Growth disorder of the medial aspect of the proximal tibial physis, with abrupt medial angulation of the proximal tibia distal to the epiphysis, leading to varus angulation of the proximal tibia and medial rotation of the tibia.
Epidemiology:
  1. Risk factors
  2. Differential diagnosis
Classification:
  1. Infantile: (Early onset)
  2. Juvenile: (Late onset)
  3. Adolescent: (Late onset)
Clinical Features:
  1. Infantile:
  2. Juvenile/Adolescent:
Radiographic Features:
  1. Infantile:
  2. Juvenile/Adolescent:
Histologic Features:
  1. Islands of densely packed hypertrophied cartilage cells, not in the usual columnar organization
  2. Acellular fibrous cartilage
  3. Abnormal groups of capillary vessels
Staging: (Langenskiold, JBJS, 1964)
  1. I: irregular metaphyseal ossification combined with medial and distal protrusion of the metaphysis
  2. II, III, IV: evolves from a mild depression of the medial metaphysis to a step-off of the medial metaphysis
  3. V: increased slope of medial articular surface and a cleft separating the medial and lateral epicondyle
  4. VI: bony bridge across the physis
Management:
  1. Non-operative
  2. Operative
REFERENCES
  1. Blount, W.P. Tibia vara. J Bone Joint Surg 19(1): 1-29, 1937.
  2. Greene, W.B. Infantile tibia vara: Instructional course lecture. J Bone Joint Surg 75A(1): 130-142, 1993.
  3. Henderson, R.C. Adolescent tibia vara: Alternatives for operative treatment. J Bone Joint Surg 74A(3): 342-350, 1992.
  4. Hoffman, A. Blount's disease after skeletal maturity. J Bone Joint Surg 64A(7): 1004-1009, 1982.
  5. Langenskiold, M.D. Tibia vara, osteochondrosis deformans tibiae. J Bone Joint Surg 46A(7): 1405-1420, 1964.
  6. Loder, R.T. Infantile tibia vara. J Ped Orthop 7: 639-646, 1987.
  7. Schoenecker, P.L. Blount's disease: A retrospective review and recommendations for treatment. J Ped Orthop 5: 181-186, 1985