Validation of goniometric measurements of rotational laxity of the canine stifle.

Abstract

OBJECTIVE: To validate goniometric measurements of stifle rotational laxity in dogs in an ex vivo study and determine their reproducibility in a clinical setting. METHODS: In phase 1, 16 normal pelvic limbs were harvested from 8 canine cadavers. Goniometric measurements, including tibial torsion (TT) and internal and external rotation of the stifle were compared within limbs and between groups before and after each of the following modifications: transection of the cranial cruciate ligament (CCL) as a model of rotational hyperlaxity (CCL deficiency [CCLD]), rotational osteotomy as a model of TT, and CCLD+TT. A lateral fabella suture (LFS) was then placed in each limb before measurements were repeated. Phase 2 was a clinical prospective study of 51 awake dogs (102 limbs). Torsion and stifle rotations were measured by 2 investigators, 1 in triplicate. Correlation coefficients were calculated to assess intra- and interinvestigator reproducibility. RESULTS: In phase 1, internal rotation increased by 10.6 ± 7.2° after CCL transection. Placement of an LFS did not influence TT but decreased internal rotation within limbs. Internal rotation of the stifle was increased in all CCLD limbs (CCLD, 32.6 ± 7.6°; CCLD+TT, 33.0 ± 12.3°) compared to intact limbs (24.4 ± 5.8°) and CCLD limbs repaired with LFS (6.3 ± 5.1°). In phase 2, correlation coefficients within and between investigators were > 0.9 for TT and internal rotation angles of the stifle. CONCLUSIONS: Goniometry allowed the detection of experimentally induced hyperlaxity and was reproducible in awake dogs. CLINICAL RELEVANCE: Goniometric assessment of stifle rotation should be considered during routine orthopedic examination.