Diagnosis and management of the surgical complication of postoperative "slipped" medial rectus muscle: A new "tendon step test" and outcome/results in 11 cases

Objectives: To report our experience in eleven patient with a "slipped" medical rectus after prior surgery. We describe the "tendon step test" as the basis for early intraoperative suspicion of a "slipped" muscle. The diagnostic translucent empty capsule is usually identified following careful dissection of the fibrous tissue surrounding the capsule. Methods: The patients medical records were reviewed and analyzed retrospectively. Preoperatively, adduction had been normal in one case, mild to moderately limited in eight and severely limited in two. Proptosis and widening of palpebral fissure were inconstant features. We had performed the tendon step tests intraoperatively and proceeded with further dissection to reveal the empty capsule to confirm the diagnosis. The procedure had consisted of excision of the empty capsule attached to the intended scleral insertion, advancement and reattachment of the retracted "slipped" muscle within its capsule to the sclera. In addition, the ipsilateral lateral rectus was recessed in 4 cases. Results: All patients had presented postoperatively with consecutive exotropia. The tendon step test was positive in all cases. The final results of corrective surgery were "satisfactory" in eight patients (deviation ≤±10Δ), "fair" in two (≤±15Δ) and "unsatisfactory" in 1 (>±15Δ). Conclusion: The tendon step test described herein along with the identification of the empty capsule are valuable adjuncts to the diagnosis of "slipped" muscle.