Nerve Testing Key to Limb Lengthening Success Rates

For Immediate Release:July 31, 2003

SINAI HOSPITAL RESEARCHERS FIND NERVE TESTING KEY TO LIMB LENGTHENING SUCCESS RATES

Experts at Sinai Hospital have found that recovery rates from nerve injury in limb lengthening patients are significantly faster and higher when diagnosed by PSSD, a pressure specified sensory device, than by clinical symptoms or nerve conduction studies alone. The study, published in the August 2003 issue of The Journal of Bone and Joint Surgery, is a ten-year retrospective evaluation and the only one of its kind in terms of number of cases evaluated and number of years studied.

Limb lengthening is a surgical procedure in which the bone is broken and slowly pulled apart. As new bone forms to fill in this space, the soft tissues and nerves are stretched as well. If nerve injury is suspected, the study indicates that the most sensitive method for accurate diagnosis is the PSSD test.

"Nerve injury associated with lengthening has been one of the critic's most common arguments against the procedure," said Dror Paley, M.D., co-director of the International Center for Limb Lengthening at Sinai and a world-renowned expert in this specialty. "While nerve injury is a possible complication [a one in ten chance], this study proves that early detection with PSSD plus appropriate intervention results in successful lengthening without compromising lengthening goal or outcome."

The PSSD is a noninvasive instrument that measures pressure in grams per square millimeters required to feel light touch. "We take a small instrument [a two-pronged pressure transducer] and gently press it against the skin on the limb undergoing lengthening," said Anil Bhave, P.T. and director of the Gait Lab at the Rubin Institute for Advanced Orthopedics. "Meanwhile, the patient, whose view of the instrument is blocked, holds a device with a trigger button and is instructed to press the trigger as soon as he or she feels a light touch. The instrument sends information to the computer that tells us if the nerve is in trouble or not."

Treatment for nerve injury may include slowing down the rate of distraction (stretching the bone apart) or a nerve decompression, a surgical procedure in which the tissues around the affected nerve are cut to open up a place for the nerve to continue growing.

"The Center has a 100 percent nerve injury recovery rate," said Paley, who explained that nerve decompression was once thought to be too aggressive. "Early diagnosis and aggressive treatment by means of a decompression, a procedure that is simple and effective, are the contributing factors to our success rate."

The study also identified groups that fall in a high- or low-risk category. "All patients are given the PSSD prior to surgery to establish a base," explained Bhave. "After surgery, the high-risk patients, which have been identified as those with dwarfism and with double level lengthening, are tested every two weeks, while the low-risk group is tested only when positive clinical signs, such as radiating or burning pain, tingling or numbness, present themselves." Children or adults with limb length discrepancies, limb deformities from birth, short stature (such as dwarfism), or victims of accidents are among those who may benefit from lengthening treatment.

The International Center for Limb Lengthening, part of Sinai's Rubin Institute for Advanced Orthopedics, is the most experienced center in the United States in regard to limb lengthening.# # #