Does surgeon handedness affect the outcomes after primary total knee arthroplasty? A retrospective cohort study

Abstract

BACKGROUND

Various factors affecting the outcomes after primary total knee arthroplasty (TKA) have been investigated in the literature; however, the effect of surgeon handedness on outcomes has rarely been addressed.

AIM

To assess whether the radiological and functional outcomes differ between right and left primary TKA when operated by right-handed surgeons.

METHODS

A retrospective evaluation of 370 TKAs performed by right-handed surgeons [47.8% right TKAs, dominant side (Group D), and 52.2% left TKAs, non-dominant side (Group N)]. The radiological outcomes were the overall alignment measured as the hip-knee-ankle (HKA) angle, and the tibial and femoral component alignment in the coronal plane measured as the medial tibial proximal angle (MPTA) and mechanical lateral distal femoral angle (mLDFA). The percentage of each alignment outside the accepted safe zone values (outliers) were calculated. The functional outcome at the last follow up was evaluated per the Knee Society Score (KSS) System for 206 knees only.

RESULTS

There were no difference in patients' basic characteristics or in postoperative radiological or functional outcomes between Group D and Group N as follows: HKA, 177.96° ± 3.13° vs 178.55° ± 3.38° (P = 0.082), MPTA, 88.90° ± 2.61° vs 89.43° ± 2.71° (P = 0.056), mLDFA, 90.16° ± 2.54° vs 89.76° ± 2.53° (P = 0.140), and KSS, 80.59 ± 14.73 vs 79.56 ± 15.64 (P = 0.628). There was no significant difference in the percentage of outliers in the HKA and mLDFA between groups. For the MPTA, Group D had significantly more implants within the safe zone than Group N, 53.7% vs 41.4% (P = 0.022). There was no difference regarding using intramedullary (IM) vs extramedullary (EM) alignment for the tibial cut between both groups (P = 0.687). In Group D, there was no significant difference in mean MPTA between IM (88.86° ± 3.26°) and EM (88.93° ± 1.76°) methods (P = 0.862); however, EM resulted in significantly fewer outliers compared to IM (29.2% vs 63.6% respectively; P < 0.001). In Group N, the EM method produced a significantly more valgus alignment than IM (90.38° ± 1.99° vs 88.56° ± 3.00°, P < 0.001), but this did not translate into a significant reduction in outliers (P = 0.650).

CONCLUSION

The overall radiological and functional outcomes after primary TKA were unaffected by the surgeon's handedness; however, the placement of the tibial component was significantly more precise on the dominant side with fewer outliers.

Keywords: Clinical outcomes; Radiological outcomes; Surgeon handedness; Total knee arthroplasty; Functional laterality; Psychomotor performance

Core Tip: Factors affecting primary total knee arthroplasty (TKA) outcomes could be related to the patient, surgical technique, and the surgeon. One rarely investigated surgeon-related factor is surgeon handedness. We evaluated 370 knees operated by right-handed surgeons, where 177 TKAs were right (dominant side) and 193 were left (non-dominant side). We found no difference between sides regarding the overall limb and individual component coronal plane alignment; furthermore, there was no difference in the functional outcomes between sides, but there were fewer tibial component outliers in the dominant side. Surgeons operating on the non-dominant side should pay attention during the tibial cut and implant insertion.