Long-term Failure of Thermal Shrinkage for Laxity of the Anterior Cruciate Ligament

Background: Appropriate treatment for anterior cruciate ligament laxity, owing to partial tears of the native ligament or lax reconstruction, is unclear. Studies suggest that a significant percentage of these untreated tears may progress to complete tears or the patient may develop additional injuries to the meniscus or articular cartilage. Shrinkage of the ligament or graft using thermal energy has been proposed as a solution for this problem.

Purpose: To evaluate the long-term results using thermal energy to shrink laxity of the anterior cruciate ligament.

Study Design: Case series; Level of evidence, 4.

Methods: Nineteen patients with partial tears of the anterior cruciate ligament (n = 14) or stretched anterior cruciate ligament grafts (n = 5) underwent thermal shrinkage treatment. Fourteen were available for follow-up at 1 and 5 years. At 1 year, there were 12 partial tears and 2 grafts available for evaluation. At 5 years, there were 10 partial tears and 4 grafts. Preoperative, postoperative, and intraoperative stability testing was performed using the KT-1000 arthrometer. Clinical results were evaluated using the Cincinnati and Lysholm scoring systems.

Results: Intraoperative shrinkage averaged 2.12 mm (17%, P < .0001). At 1 year, 12 of the 14 patients remained stable (86%) with a negative Lachman test result and mean KT-1000 arthrometer maximum side-to-side score of 1.29 mm (P < .001). The 2 failed shrinkages were partial tears of the native anterior cruciate ligament. For these 12 patients, Cincinnati scores improved from 53 to 89 (P < .0001), and Lysholm scores improved from 55 to 89 (P < .0003). At 5-year follow-up, 11 of 13 patients had gone on to complete failure (85%, P < .002; 8/9 partial tears and 3/4 grafts).

Conclusion: Thermal shrinkage provides short-term benefit in the treatment of anterior cruciate ligament laxity but leads to catastrophic failure in the majority of patients at long-term follow-up. We can no longer recommend this procedure for the treatment of anterior cruciate ligament laxity.