Summary

The use of a medial steep oblique incision along the saphenous nerve path during Total Knee Arthroplasty, which allows kneeling and preserves the sensation of the anterior knee, improved postoperative outcomes.

Abstract

Objective

A medial steep oblique incision was developed to minimize damage to the infrapatellar branch of the saphenous nerve and preserve skin sensation in total knee arthroplasty (TKA), facilitating kneeling post-surgery. The study investigated the effectiveness of this incision compared to traditional medial oblique incisions.

Methods

The study included 34 knees (steep oblique group) that underwent primary TKA using the new incision method from April 2021. This group was compared with 37 knees (oblique group) that had previously undergone TKA using traditional medial oblique incisions. The incision was made along a line connecting the adductor canal and the lateral attachment of the distal patellar tendon. The dermis was incised without damaging the patellar tendon, and subcutaneous tissue was carefully separated. Proximally, the medial edge of the vastus medialis muscle was exposed, and entry was made between the muscle belly and fascia. Distally, subcutaneous tissue was dissected along the medial edge of the patella and patellar tendon as usual. One year postoperatively, skin sensation, the ability to kneel, and KOOS (Knee injury and Osteoarthritis Outcome Score) were assessed and compared.

Results

In the oblique group, only 5% of cases had completely preserved sensation, while 76% had areas of numbness. In contrast, 88% of cases in the steep oblique group had completely preserved skin sensation, and no cases had areas of numbness. Kneeling was possible in 27% of the oblique group but 91% of the steep oblique group. The KOOS scores for sports activities, quality of life, and symptoms were significantly higher in the steep oblique group.

Discussion

The steep oblique group showed 88% complete preservation of skin sensation, with the remaining 12% experiencing only mild sensory loss. This indicates that the medial steep oblique incision effectively preserves skin sensation. Among the 9% (3 knees) of the steep oblique group who could not kneel, one knee had persistent pain due to patellofemoral joint malalignment, and the other two had insufficient muscle strength. None of the cases in this group had sensory deficits that prevented kneeling. The improvement in KOOS scores, particularly in sports activities, quality of life, and symptoms, suggests enhanced patient satisfaction with the new incision technique.

Conclusion

The medial steep oblique incision in TKA preserved skin sensation, enabled kneeling, and improved KOOS scores in three categories, indicating better postoperative outcomes and patient satisfaction.