Flexion deformity and laxity as a function of knee position at the time of tensioning of rigid anatomic hamstring ACL grafts.

BACKGROUND: Anatomic ACL grafts routinely display the anisometric length-tension behaviour seen in the native ligament with maximum length in full knee extension. Recent improvements in hamstring graft preparation and fixation have improved graft rigidity to the point where total graft lengthening after implantation may be less than 1 mm. Despite this it remains common practice to fix these grafts in a knee flexed position. METHODS: Nineteen participants underwent all-inside ACL reconstruction with optimally preconditioned 4 strand semitendinosus grafts using bi-cortical adjustable suspensory loop fixation. Using a computer navigation system, baseline measures of anisometricity, extension range, and tibial rotation were made. The graft was tensioned and provisionally fixed with the knee flexed 5° beyond its anisometric point and extension range recorded. The graft was then definitively fixed with the knee fully extended and extension range and tibial rotation recorded again. Anterior laxity measurements were made pre-operatively and postoperatively using a manual arthrometer and compared to those from the contralateral limb. RESULTS: Fixing the graft with the knee flexed produced a mean FD of 10.9° (p < 0.0001) and fixing in extension restored full extension (p = 0.661). Fixing in extension restored anterior laxity at 30° (p = 0.224) and at 90° (p = 0.668). There were very strong correlations between post-operative and control extension range (r = 0.931, p < 0.0001) and anterior laxity and 30° (r = 0.830, p < 0.0001) measures. Constraint of tibial internal rotation increased by 2.9° during the pivot-shift (p < 0.001) and increased with pivot shift grade (r = 0.474, p = 0.040). CONCLUSION: Fixing rigid anatomic hamstring grafts in a knee flexed position routinely produces a flexion deformity. Tensioning and fixing grafts with the knee fully extended restores full extension and anterior laxity at 30° and 90°. Rotational constraint is significantly improved and correlates with the pivot-shift grade. CLINICAL RELEVANCE: Rigid anatomic grafts should be tensioned and fixed with the knee fully extended.

Computer-Assisted Kinematic and Mechanical Axis Total Knee Arthroplasty: A Prospective Randomized Controlled Trial of Bilateral Simultaneous Surgery.

BACKGROUND: Randomized controlled trials of kinematic alignment (KA) and mechanical alignment (MA) in primary total knee arthroplasty (TKA) have to date demonstrated at least equivalence of KA in terms of clinical outcomes. No trial of bilateral TKA has been conducted so patient preference for one technique over the other is unknown. METHODS: Forty-one participants underwent computer-assisted bilateral TKA. The outcome measures were as follows: (1) joint range of motion and functional scores including the KOOS, the KOOS JR, Oxford Knee Score, and the Forgotten Joint Score at a minimum of 2 years; (2) preference and perception of limb symmetry; (3) intraoperative alignment data; (4) release and gap balance data; and (5) postoperative radiographic joint angles. RESULTS: There were no significant differences with respect to flexion range (P = .970) or functional scores (mean KOOS, P = .941; KOOS JR, P = .685; Oxford Knee Score, P = .578; FJS, P = .542). Significantly more participants who favored one knee preferred their KA TKA (P = .03); however, half of the patients had no preference and the overall numbers were small. Only 3 participants perceived any limb asymmetry (P < .001). More releases were required in the MA group (P = .018). Standing hip-knee-ankle angle means and frequency distributions were similar (P = .097 and P = .097, respectively). CONCLUSION: Clinical outcomes were equivalent at 2 years. Significantly more participants preferred their KA joint. Fewer releases were required using a KA technique. Participants were visually insensitive to modest hip-knee-ankle angle asymmetry. LEVEL OF EVIDENCE: Level 1.

Closed Incision Negative Pressure Wound Therapy vs Conventional Dry Dressings After Primary Knee Arthroplasty: A Randomized Controlled Study.

BACKGROUND: The purpose of this study was to assess the effect of negative pressure wound therapy (NPWT) on quality of life (QoL), wound complications, and cost after primary knee arthroplasty. METHODS: A prospective analysis of 33 patients undergoing primary knee arthroplasty performed by 3 surgeons in one institution. The first 12 patients (3 bilateral and 9 unilateral) had conventional dry dressings (CDD) applied and cost of dressings was assessed. The other 21 patients all underwent bilateral knee arthroplasty and had either side randomized to receiving NPWT or CDD. Cost of dressings, wound complications, and QoL were compared. RESULTS: One patient had a reaction to the NPWT requiring readmission. Another had persistent wound drainage that required NPWT application. There were no wound issues in the remaining 31 patients. The average cost in the first 12 patients was Australian dollar $48.70 with an average of 1.5 changes on ward. In the 21 patients receiving both dressings, the average cost for CDD was less (Australian dollar $43.51 vs $396.02, P ≤ .011, effect size [ES] = 1.06). When comparing QoL factors, wound leakage (0.14 vs 0.39 P = .019, ES = 1.02), and wound protection (0.16 vs 0.33, P = .001, ES = 0.021) were better in the NPWT group. There was no other significant difference in QoL factors. The average number of changes on the ward was less for the NPWT group (1.19 vs 1.38, P = .317, ES = 1.02). CONCLUSION: We found no benefit in wound healing or cost with NPWT post knee arthroplasty. There was some benefit in NPWT QoL factors less wound leakage and better protection.