A prospective randomized study in 20 patients undergoing bilateral TKA comparing midline incision to anterolateral incision

Abstract

Background Lateral flap numbness is a known side-effect of midline skin incision in total knee arthroplasty (TKA) and a cause of patient dissatisfaction. Anterolateral incision is an alternative approach which preserves the infrapatellar branches of the saphenous nerve and avoids numbness. Studies have compared both incisions, but in different patients. However, different patients may assess the same sensory deficit dissimilarly, because of individual variations in anatomy and healing responses. We compared the two incisions in the same patient at the same time, using an anterolateral incision on one knee and a midline incision on the other knee in simultaneous bilateral TKA. Other surgical steps including medial arthrotomy were idential. We also correlated subjective and objective findings. Materials and methods Twenty patients were prospectively randomized. Sensory loss and skin healing were assessed at 6, 12 and 52 weeks. Subjective preference for the knee with less numbness was charted on Wald's Sequential Probability Ratio Test. Sensation scores for touch, vibration, static and moving two-point discrimination were measured. Scar healing was evaluated using the Patient and Observer Scar Assessment Scale (POSAS). Functional scores were measured. Results A statistically significant difference favoring knees with anterolateral incision was observed in patient preference at all assessment points and this correlated with sensation scores. A statistically significant difference was observed in POSAS score favoring knees with anterolateral incision at 6 and 12 weeks which became statistically insignificant at 1 year. Functional scores remained comparable. Conclusion We recommend anterolateral incision as a safe and effective method to circumvent the problem of lateral flap numbness with midline incision. Level of evidence I.

The Effect of Sensory Deficit After Total Knee Arthroplasty on Patient Satisfaction and Kneeling Ability

“…The unknown effects of skin numbness have driven some surgeons to explore alternative approaches and minimally invasive techniques [ 3 , 7 , 15 , 19 ]. Tsukada et al.…”

“…The unknown effects of skin numbness have driven some surgeons to explore alternative approaches and minimally invasive techniques [3,7,15,19]. Tsukada et al [15] demonstrated better kneeling ability and lower occurrence of skin numbness after an anterolateral approach than a traditional midline incision.…”

Cadaveric study of the infrapatellar branch of the saphenous nerve: Can damage be prevented in total knee arthroplasty?

“…1-3,9,14,22 Being a purely sensory nerve running down the anteromedial aspect of the knee, the damage to the distal part of the IPBSN by midline incision often leads to paresthesia, hypersensitivity, or numbness of the lateral and potentially even medial and anterior parts of the knee. 1,9,[11][12][13][20][21][22] While many studies have found the association between IPBSN damage and numbness of the knee, only a few have studied the regeneration of normal sensation after IPBSN injury and have shown contradictory findings. Hopton et al, while concluding that the transection of IPBSN is unavoidable in order to achieve adequate exposure of the knee, supports the claim that subjective and objective improvement of the lateral skin flap numbness can be expected as short as 6 weeks post-operatively.…”

“…9,14 Once damaged, patients note numbness, paresthesia, or hypersensitivity of lateral skin flap of the knee. 7,9,11,13,20,21 Although the knee function largely remains intact, IPBSN injury can lead to patient dissatisfaction by affecting the ability of the patient to kneel in fear of damaging the prosthesis due to their sensory deficits. 6,13 In light of the disagreement in current literature on whether improvement of IPBSN damage ever occurs with time, surgeons should attempt to minimize intraoperative injury to the nerve or its branches.…”

“…7,9,11,13,20,21 Although the knee function largely remains intact, IPBSN injury can lead to patient dissatisfaction by affecting the ability of the patient to kneel in fear of damaging the prosthesis due to their sensory deficits. 6,13 In light of the disagreement in current literature on whether improvement of IPBSN damage ever occurs with time, surgeons should attempt to minimize intraoperative injury to the nerve or its branches. 7,8 The aim of this fresh-frozen cadaveric study was to describe the course and variability of the IPBSN and to assess whether it is possible to preserve it during a standard midline surgical approach in TKA.…”