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KMID : 1037920170040010021
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Arthroscopy and Orthopedic Sports Medicine
2017 Volume.4 No. 1 p.21 ~ p.27
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Effect of guide frame rotation on the breakage of bioabsorbable femoral cross-pins
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Choi Nam-Hong
Kim Byeong-Yeon
Park Ji-Yong
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Abstract
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Background: The exact cause of breakage of the Rigidfix (Mitek, USA) remains unclear until now. A posteriorly directed drilling would induce the tip of the cross-pin to penetrate the posterior cortex of the distal femur, resulting in breakage of the Rigidfix. We hypothesized that external rotation of the Rigidfix guide frame (GF) can reduce the incidence of broken Rigidfix.
Methods: Thirty-one patients (control group) underwent hamstring anterior cruciate ligament reconstructions using Rigidfix while the window of the Rigidfix GF jig was pointed toward the center of the lateral femoral condyle. Another 26 patients (study group) underwent the same procedure while the GF jig was rotated more externally. The two groups were compared using Lachman and pivot-shift tests, KT-1000 arthrometer testing, the Lysholm knee score, and Tegner activity scale. Follow-up magnetic resonance image were obtained to evaluate breakage of the cross-pins, violation of the posterior by tip of the cross-pin, and an angle (cross-pin angle) between the epicondylar axis and the longitudinal axis of the cross-pin.
Results: Postoperative knee stability and functional outcome scores showed no significant difference between the two groups. External rotation of the GF significantly decreased the incidence of violation of the posterior cortex and incidence of Rigidfix breakage in the study group compared to the control group (P = 0.000 and 0.047, respectively). The cross-pin angle was ?14.0° ± 8.0° in the control group and 15.9° ± 8.0° in the study group (P = 0.000). Logistic regression showed that the cross-pin angle was correlated significantly with cross-pin breakage (P = 0.0085). The cut-off value of the cross-pin angle above which breakage of the Rigidfix did not occur was ?0.5°.
Conclusion: External rotation of the GF decreased significantly the incidence of Rigidfix breakage.
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KEYWORD
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Breakage, Cross-pin, Anterior cruciate ligament, Reconstruction
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