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Does surgeon handedness affect the outcomes after primary total knee arthroplasty? A retrospective cohort study
Ahmed A Khalifa1, Ahmed M Abdelaal2, Mohamed Ma Moustafa2
1Department of Orthopaedic, Qena Faculty of Medicine and University Hospital, South Valley University, Qena 83523, Qina, Egypt. ahmed_adel0391@med.svu.edu.eg.
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.
