John Dillon

Using navigation intraoperative measurements narrows range of outcomes in TKA

Computer-assisted technology creates a new approach to total knee arthroplasty (TKA). The primary purpose of this technology is to improve component placement and soft tissue balance. We asked whether the use of navigation techniques would lead to a narrow range of implant alignment in both coronal and sagittal planes and throughout the flexion-extension range. Using a prospective consecutive series of 57 navigated TKAs, we assessed intraoperative knee measurements, including alignment, varus-valgus stress angles in extension, and varus-valgus angles from 0° to 90° of flexion comparing postimplant with preimplant. We found fewer outliers with coronal (100% of TKAs within ±2°) and sagittal (0% of TKAs with fixed flexion greater than 5°) alignment, soft tissue balancing (mean varus and valgus stress angles −3.2° and 2.3°; range, −5° to 5°), and mean femorotibial angle over flexion range 0° (−0.2°; range, −1° to 2°), 30° (−0.2°; range, −5° to 4°), 60° (−0.5°; range, −5° to 7°), and 90° (−0.2°; range, −5° to 10°). This technology allows a narrow range of implant placement and soft tissue management in extension. We anticipate improved ultimate patient outcomes with less tissue disruption.Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

A quantitative method of effective soft tissue management for varus knees in total knee replacement surgery using navigational techniques.

Abstract Total knee replacement (TKR) has become the standard procedure in management of degenerative joint disease with its success depending mainly on two factors: three-dimensional alignment and soft-tissue balancing. The aim of this work was to develop and validate an algorithm to indicate appropriate medial soft tissue release during TKR for varus knees using initial kinematics quantified via navigation techniques. Kinematic data were collected intra-operatively for 46 patients with primary end-stage osteoarthritis undergoing TKR surgery using a computer-tomography-free navigation system. All patients had preoperative varus knees and medial release was made using the surgeons experience. Based on these data an algorithm was developed. This algorithm was validated on a further set of 35 patients where it was used to define the medial release based on the kinematic data. The post-operative valgus stress angles for the two groups were compared. These results showed that the algorithm was a suitable tool to indicate the type of medial release required in varus knees based on intra-operatively measured pre-implant valgus stress and extension deficit angles. It reduced the percentage of releases made and the results were more appropriate than the decisions made by an experienced surgeon.

Correlation of total knee replacement wound dynamic morphology and dressing material properties

This item discusses correlation of total knee replacement wound dynamic morphology and dressing material properties. It is presented in the program and abstracts of the XXI Congress, International Society of Biomechanics.

Raising standards of orthopaedic wound care: a prospective, comparative evaluation of a modern dressing design

Background: Chronic wounds have for many centuries represented a major source of morbidity and mortality in patients. In the modern era we realise that these wounds also produce a major psychological impact to the patients, and a financial burden to the healthcare systems around the world. Ever since the first skin grafts were attempted in India around 2000bc for the reconstruction of punitatively amputated noses, the surgical profession and medical sciences have been searching for the panacea to treat chronic wounds. Yet as our understanding of the aetiology of chronic wounds deepens we realise that the varied nature of the wound pathogenesis means there will never be a ‘‘one cure for all’’ treatment. In this way we can see that a split skin graft is certainly not the optimal option for many patients, and that alternatives must be found. Method: In two selected patients with chronic static laparotomy wounds we demonstrate the successful use of a biological tissue regeneration therapy (Apligraf s) in the management of these recalcitrant wounds. Conclusion: In carefully selected patients under the care of a Multidisciplinary Wound Healing Team, the use of cell based tissue regeneration products may provide a valuable adjunct to standard wound healing regimens.Introduction: Prevention of infection in orthopaedics remains a constant challenge. In spite of increasing evidence to support use of modern dressings many units use traditional adhesive dressings, which can cause wound healing problems. Our modern dressing design hydrofibre/hydrocolloid (HF/HC) was highly effective following hip and knee replacements in a national arthroplasty unit. The aim of this study was to evaluate this dressing in a district hospital to see if similar clinical outcomes could be achieved. Methods: Prospective evaluation of the modern dressing involved 89 consecutive elective and trauma patients from October 2007–January 2008. Outcome measures included blistering, wear time, dressing changes, delayed discharge and SSI rate. Results were compared to a traditional dressing currently used. Results: 65 patients HF/HC group, 24 Traditional group. CUSUM tool set an upper alert limit of 5% blister rate. Traditional group breached upper alert limit after 8 cases. It was decided unethical to continue after 24 cases. Comparison of HF/HC with Traditional showed blistering 1.5% versus 16.7%, wear time 4.8 versus 1.4 days and dressing changes 0.9 versus 2.8. Delayed discharge 0% compared with 4.2%. SSI rates 0% versus 4.2%. All outcome differences were statistically significant except delayed discharge (p<0.05, Mann Whitney, chi-square tests). Conclusion: Implementation of evidence-based modern wound care into a district general orthopaedic department achieved improved clinical outcomes with elective and trauma patients, similar to those of a national arthroplasty unit.This supports the use of the dressing and highlights the ongoing concerns of traditional dressings used in orthopaedics.

ASSESSMENT OF DYNAMIC TOTAL KNEE ARTHROPLASTY FUNCTION BY TWO DIFFERENT SURGICAL TECHNIQUES (COMPUTER ASSISTED AND TRADITIONAL INSTRUMENTATION) USING GAIT ANALYSIS

This item discusses assessment of dynamic total knee arthoplasty function by two different surgical techniques (computer assisted and traditional instrumentation) using gait analysis. It was presented at the XXI Congress, International Society of Biomechanics.