Increased intracapsular pressures after unstable slipped capital femoral epiphysis.

BACKGROUND

Osteonecrosis of the femoral head is the most dreaded complication associated with an unstable slipped capital femoral epiphysis (SCFE). We hypothesize that the hip joint pressure will be increased in unstable slips, confirming that emergent treatment and decompression are warranted.

METHODS

Thirteen unstable SCFE hips were evaluated. Hip pressure monitoring was performed. Postcapsulotomy measurements were also performed in all of the patients. Five of these under gentle manipulation. Six patients underwent measurement of the hip pressure on the unaffected side.

RESULTS

The mean pressure on the affected hip was 48 mm Hg. The mean pressure on the unaffected side was 23 mm Hg. There was a significant increase in intraarticular hip pressure after attempted manipulation (mean, 75 mm Hg).

DISCUSSION

Hip pressures are increased in unstable SCFE to levels higher for those of a compartment syndrome probably causing a tamponade effect. There is a need to perform a capsulotomy if manipulation is performed.