EARLY OUTCOMES AND COMPLICATIONS IN HIGH RISK PATIENTS UNDERGOING PRIMARY TOTAL KNEE ARTHROPLASTY.

Abstract

Introduction: The emergence of Independent Sector Treatment Centres (ISTCs) in the UK for the provision of elective orthopaedic services began in 2002–3. Within our trust the bulk of elective orthopaedic surgery is performed in an ISTC however there is a small but significant cohort of patients who are deemed not suitable for treatment at the ISTC. Patients with a BMI (body mass index) ≥40 or an ASA (American society of anaesthesiologists) grade of 3 or more are automatically rejected. With increasing levels of obesity and an aging population the size of the reject cohort is going to rise. These patients are then returned to the NHS to be placed on a new (complex elective) waiting list for their surgery. The aim of this study was to assess the early outcomes and complications following primary knee arthroplasty on our high risk patients.

Methods: A retrospective review of a consecutive series of 214 primary knee arthroplasties in patients rejected from the ISTC was performed. Data (demographics, ASA grade, BMI, length of stay, complications, range of knee movement and requirement for HDU/ICU) were collected from preoperative assessments, inpatient notes, anaesthetic charts, discharge summaries and follow up clinic letters. All patients were followed up for a minimum of 6 months.

Results: 155 (72%) patients were female. 140 (65%) had ASA of 3 or more. 88 (41%) had a BMI of 40 or more. Median length of stay was 8 days (6 to 11 IQR) and did not vary with increasing BMI but increased to 10 days in the ASA 3 and 12 days in the ASA 4 group. There were a total 90 complications in 71 patients. The most common complications were 22 superficial wound infections (10.3%), 11 Pneumonias (5.1%), and 9 symptomatic DVTs (4.2%). There were 16 severe complications (2 Deep infections, 4 PEs, 2 CVAs, 4 acute renal failures and 4 dislocations) in 15 patients. Patients with a BMI < 40 had a total complication rate of 38% (7.9% severe) compared with 26% (5.7% severe) in BMI ≥40 group. Patients with an ASA < 3 had a complication rate of 31% (4.1% severe) vs. 34% (8.6% severe) in patients with an ASA ≥ 3. HDU/ICU beds were required postoperatively for 20 patients (9 planned and 11 unplanned). At six months 72% achieved a knee range of movement ≥ 0 to 90 degrees. Surgeons who performed high volumes of surgery in this difficult group had lower complications then lower volume surgeons.

Conclusion: This is one of the largest consecutive groups of high risk patients undergoing primary total knee arthroplasty. Our results show that elevated BMI does not appear to adversely affect complication rates in knee arthroplasty in our series although ASA grades of 3 and 4 are associated with increased length of stay and complication rates. It is also clear that small groups of surgeons operating on these difficult patients may reduce complications.