Outcomes of total knee arthroplasty in degenerative osteoarthritic knee with genu recurvatum.

BACKGROUND

This study aimed to assess the incidence of genu recurvatum without neuromuscular disorders in knees that underwent navigation-assisted total knee arthroplasty (TKA), to evaluate short-term radiologic and clinical results of navigation-assisted TKA in genu recurvatum, and to evaluate differences in results according to the degree of pre-operative hyperextension and type of implant and insert.

METHODS

This study retrospectively reviewed 510 knees that underwent navigation-assisted TKA from January 2005 to December 2011. The incidence of knees that showed hyperextension of ≥5° (genu recurvatum) on navigation, and the accompanying alignment were evaluated. It assessed radiologic, intraoperative, and clinical results in recurvatum and control groups by using propensity score matching.

RESULTS

A total of 465 knees underwent navigation-assisted TKA for degenerative osteoarthritis. Genu recurvatum was observed in 55 knees (11.8%). Of these, 41 knees (74.5%) had degree of hyperextension between five degrees and 10°, and 47 (85.4%) had varus alignment. The thickness of the resected distal femur in the recurvatum group (7.6±1.6mm) was less than that in the control group (8.4±1.4mm, P=0.001). The thickness of the insert in the recurvatum group (12.5±2.3mm) was greater than in the control group (10.8±1.5mm, P<0.001). The sagittal alignment at the final follow-up was 1.3±3.4° in the control group and -0.1±0.7° in the recurvatum group (P=0.003). Subgroup analyses in the recurvatum group showed no significant difference in sagittal alignment and patient-related outcomes by degree of pre-operative hyperextension and implant/insert type (P>0.05 for all parameters).

CONCLUSIONS

Genu recurvatum was not uncommon among patients undergoing primary TKA. This review obtained satisfactory short-term clinical and radiologic results, with a smaller distal femoral resection and thicker insert.