Review Question - QID 4524

The clinical presentation is consistent with a sciatic neuropathy following THA in a patient that does not tolerate AFO bracing. Posterior tibialis tendon transfer is the next most appropriate step in treatment.

Sciatic neuropathy, especially involving the common peroneal branch, is a known complication of total hip arthroplasty. Typically a patient is adequately treated with an AFO. In some clinical situations an AFO is not tolerated, and a tendon transfer is required. The posterior tibial tendon is the most commonly used donor muscle. A tendon transfer is feasible only if the tendon possesses at least 4/5 power. There is a loss of 1 MRC grade of strength following transfer.

Rodriguez et al. retrospectively reviewed the results of the Bridle procedure 10 patients (11 feet) with a foot drop. The Bridle procedure consists of a posterior tibial tendon transfer through the interosseous membrane to the dorsum of the foot with a dual anastomosis to the tendon of the anterior tibial and a rerouted peroneus longus in front of the lateral malleolus. In their study all 11 feet were brace-free at final followup at 6.68 years.

Yeap et al. retrospectively reviewed 12 patients who were treated with tibialis posterior tendon transfer for footdrop. They found good/excellent patient satisfaction in 10/12 patients. Additionally they found favorable variables for a good outcome include common peroneal nerve palsy over sciatic nerve palsy, male gender less than 30 years of age.

Figure V is a Video that shows a right footdrop with high steppage gait. Figure A shows normal ankle radiographs. Figure B shows the results of dynamometer testing described above. Illustration A shows the Bridle procedure. The left panel shows how the tibialis posterior tendon (C) is tunneled through the interosseous membrane and through a slit in the tibialis anterior tendon (A) and inserted into the second cuneiform. The peroneus longus (B) is also transected and the distal stump is routed anterior the lateral malleolus and anastomosed to the tibialis anterior and tibialis posterior (at the slit where it passes through the tibialis anterior). The right panel shows retrieval of the tibialis posterior tendon above the ankle and passage through a window in the interosseous membrane.

Incorrect Answers:
Answer 1: There is no arthrosis of the ankle joint and several tendons possess sufficient strength to make a tendon transfer feasible. Tendon transfer should be attempted first.
Answer 3: The anterior tibial tendon attaches to the plantar-medial aspect of the medial cuneiform and 1st metatarsal base. This muscle is weak (0/5 power) and transfer of its tendon muscle will not correct footdrop.
Answer 4: The peroneus longus attaches to the medial cuneiform and 1st metatarsal (plantar-posterolateral aspect). This muscle is weak (2/5 power) and transfer of this tendon will not correct footdrop. Gastrocnemius recession will not increase the effectiveness of this transfer as there is no gastrocnemius contracture.
Answer 5: The flexor hallucis longus is a secondary plantar flexor of the ankle. Its power is not mentioned in the question stem. But it is a less desirable tendon transfer compared with the posterior tibialis tendon. TAL will not increase its effectiveness. TAL is not necessary as there is dorsiflexion to 10degrees past neutral with the knee extended.