Purpose: The purpose of this study was to evaluate whether the expectable postoperative pain relief following valgus high tibial osteotomy (HTO) is reliably predictable with the temporary use of an unloading knee brace preoperatively.
Methods: Fifty-seven patients with symptomatic varus malalignment were treated with a valgus producing unloading knee brace for 6-8 weeks. The pain intensity in the respective knee compartment was monitored using the visual analogue scale (VAS) before and following this treatment. A "positive" Brace-Test was defined as a pain relief medially without initiated symptoms laterally. In these cases, a valgus HTO was suggested as a promising surgical option. Patients who were subsequently operated were clinically re-evaluated 1 year postoperatively to compare the postoperative outcome with the result of the Brace-Test.
Results: The mean VAS score decreased from 6.7 [standard deviation (SD) 1.6] to 2.5 points (SD 1.7) (p < 0.001) following the Brace-Test. Overall, 48 patients had a positive test. A valgus HTO was performed in 29 of them. The mean postoperative VAS score was 1.9 (SD 1.7) points with no difference to the result of the test (n.s.). Nineteen patients with a positive test initially decided for a conservative treatment. In three of nine patients with a negative test, a total knee replacement was performed.
Conclusion: This study shows that the temporary use of an unloading valgus producing knee brace may well predict future outcome of HTO surgery in terms of expectable postoperative pain relief. The Brace-Test gives both the patient and the orthopaedic surgeon more detailed preoperative information, especially in critical or borderline indications. Thus, it is a useful tool to test the unloading effect before indicating an HTO.
Level of evidence: III.