Purpose of the study: A medial incision for implantation of a total knee arthroplasty (TKA) offers an excellent surgical exposure while minimising the length of the skin opening. This incision however implies section of the proximal portion of the infrapatellar branch of the medial saphenous nerve, potentially associated with lateral hypoesthesia and formation of a neuroma (painful scar). We hypothesised that an anterolateral skin incision would produce less hypoesthesia and postoperative discomfort.

Material and methods: We conducted a prospective randomised study to compare the degree of hypoesthesia after a medial or lateral skin incision for the implantation of a TKA. Fifty-knees in 43 patients, mean age 65.9±8.4 years were included; 26 knees for the lateral incision and 24 for the medial. All patients had the same type of implant. Clinical results were assessed with WOMAC, KOOS and SF36. Semme-Weinstein monofilaments were applied to measure sensitivity at 13 characteristic points. Patients were assessed at six weeks and six months. The zone of hypoesthesia was delimited and photographed for measurement with Mesurim Pro9^®. Satisfaction with the surgery and the scar was noted. Data were processed with Statview^®; p< 0.05 was considered significant.

Results: The two groups were comparable preoperatively regarding age, gender, body weight, height, body mass index, body surface area, aetiology, and clinical score. Operative time, blood loss, and number of complications were comparable. The functional outcomes (WOMAC, KOOS, SF36) were comparable at six weeks and six months. Active flexion was significantly greater at six months in the lateral incision group (p=0.03). The zone of hypoesthesia was significantly smaller in the lateral incision group at six weeks (p< 0.01) and at six months (p< 0.01), as were the number of points not perceived on the filament test (p< 0.01 in both cases) while the length of the incision was comparable (p> 0.05). This was associated subjectively, with less loss of sensitivity and less anterior pain reported by the patient at six months.

Discussion: Lateral and medial incisions enable comparable functional outcomes. The lateral incision produces less hypoesthesia and less anterior pain. This improves the immediate postoperative period and facilitates rehabilitation as is shown by the gain in flexion at six months.

Purpose: Antero-medial parapatellar skin incision in total knee arthroplasty (TKA) provides excellent surgical exposure with minimal skin incision length. However, it is associated with the infrapatellar branch of the saphenous nerve section, leading to antero-lateral knee hypoesthesia and sometimes painful nevroma. We hypothesized that

antero-lateral skin incision in TKA produces a lower rate of hypoesthesia compared to the medial parapatellar cutaneous approach, and

Method: A total of 69 knees in 64 patients who underwent TKA were randomized for antero-medial (n=35) or antero-lateral (n=34) skin incision. Mean age was 66.4±8.2 years. Functional outcome was assessed by WOMAC, KOOS and SF-36 scores pre-operatively and at six weeks, six months and one year follow-up. Range of motion (active and passive flexion and extension) was measured. The area of hypoesthesia was analyzed in a standardized manner by an independent observer using a calibrated Semme-Weinstein monofilament applied on 13 reference points. A digital photograph was taken, and the area of hypoesthesia was then measured informatically (Mesurim Pro^® software). Patient satisfaction with their scar and their surgery was evaluated. Statistical analysis was carried out with p< 0.05 considered as significant.

Results: The two groups were comparable pre-operatively. There was no significant difference in functional outcome (WOMAC, KOOS, SF-36 scores) at six weeks, six months and one year between the two groups. Active and passive ranges of motion were comparable. The area of hypoesthesia and the number of non-perceived points in the monofilament test were significantly lower after antero-lateral incision at six weeks (p=0.007 and p=0.02, respectively) and 6 months (p=0.02 and p=0.005, respectively). At one year, the area of hypoesthesia was lower in the antero-lateral group, but was not significant (p=0.08). Antero-lateral incision patients reported a lower rate of subjective sensitivity loss and anterior knee pain at six weeks, six months and one year.

Conclusion: Antero-medial and antero-lateral parapatellar skin incisions in TKA have a similar functional outcome. However, antero-lateral cutaneous incision produces a lower rate of hypoaesthesia and less anterior knee pain in the early recovery period.

Introduction and Aims: Although many analgesia modalities have been tried, total knee arthroplasty remains a painful procedure and parenteral narcotics still play a major role in post-operative pain control. We want to know if peri-articular large dose injection of local anaesthetics reduces narcotics administration and their side effects.

Method: Thirty-six patients undergoing a total knee replacement were randomised to two treatment groups. The experimental group received peri-articular large dose infiltration of Ropivacaine (local anaesthetic) during surgery and on day one after surgery via an intra-articular catheter. The pain control was completed with a self-delivering morphine pump. The control group received the morphine pump alone. The therapists recording post-op data were blind to the treatment group. Narcotics consumption, pain control, medication side effects, complications, range of motion and patient satisfaction were monitored. Ropivacaine serum levels were measured in the early post-operative period.

Results: Although satisfaction was very high in both groups, morphine consumption was significantly lower for the infiltration group: 29 mg/24h compared to 51 mg/24 (p< 0.01) and 47 mg/40h compared to 71 mg/40h (p< 0.04). The post-operative pain evaluated with visual analogue scale (0–10) was reduced significantly on the day of surgery 2.6 vs 5.0 (p< 0.04) and at exercise on day one post-op: 4.9 vs 7.0 (p< 0.01). There was no significant difference in post-operative range of motion at five days post-op. The surgical time was increased significantly by 18 minutes in the infiltration group 126 vs 108 minutes (p< 0.05). Complication rate was not significantly different for both groups (infiltration vs control): nausea symptoms 2.2h/48h vs 5.4h/48, confusion two subjects in each group, constipation three subjects in each group and one deep vein thrombosis per group. No complication was related to the addition of the infiltration of the local anaesthetics and the serum levels were in a safe range.

Conclusion: This peri-operative local anaesthetics infiltration protocol offer many benefits for the patients undergoing a total knee arthroplasty. It is improving the pain control, reducing the amount of narcotics consumption and is a safe procedure.