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Complications of Total Knee Arthroplasty and Evidence Basis for Outcomes of Knee Arthroplasty
The scientific basis for total knee arthroscopy (TKA) has had an interesting and exciting journey over the last five decades. A few pragmatic and visionary surgeons laid foundational principles, moderated the designs, and founded this specialty. I have no doubt that Dr. Krackow was among those select few. Dr. Krackow believed in an equitable distribution of opportunity and propagation of knowledge across borders for the benefit of humanity. The eclectic bunch of fellows from various backgrounds whom he encouraged and recruited stands testimony to that philosophy. His prescience in recording audio during patient counseling and providing one tape to the patient and retaining one for internal documentation is a genius technique to avoid long-term dissonance if there are adverse outcomes and to encourage family members to partake in decision making in absentia. He encouraged intellectual debate and insisted on hands-on training of fellows and residents with paternal firmness and rigorous academic pursuit. His patient-counseling strategy always began with no assumption of patient knowledge of disease pathology and progressed on to the usage of metal and plastic to accomplish pain relief described in simple language. He combined science, humor, and grace to convey information, and his sartorial taste communicated class and confidence in his surgical skills. This compendium is a tribute to a great human being, excellent teacher, and a master artisan.
Patients who have knee arthritis present mostly with a painful, stiff knee with or without deformity with significant limitations in the quality of life (QOL). The expectation after a knee arthroplasty is a long-lasting, pain-free functional range to full range of motion (ROM) with no deformity. The surgeon’s role is to educate the patient about the possibility of success and help define a successful outcome from the patient’s perspective. The desirable outcomes after knee arthroplasty are symptomatic relief, recovery of function and restoration of desirable alignment . One of the important aspects of the surgical discussions with patients involves reviewing the risk of surgical complications. Knee arthroplasty surgery does provoke anxiety in some patients and a candid discussion helps to clear doubts about the surgery. Evidence-based discussion on complications eases anxiety and helps with objective decision making.
Each surgeon’s philosophy of patient counseling evolves over time, with contributions from mentors, patient behavior, societal expectation, and cultural imperatives. The fundamental question is how much information is too much for the patient in decision-making. The surgical discussion has ethical, moral, and legal dimensions. The information provided should be factually accurate and balanced about the advantages, limitations, and success rates.
Outcomes
Patient satisfaction is an important factor in the outcomes assessment of TKA in end-stage arthritis. There are many tools that assess total knee outcomes, but recently the patient-reported outcome measures (PROMs), where there is direct patient reporting rather than an indirect assessment, have increased in importance. The orthopedic registries are an important source of decision-making. At present, there is a heterogeneity between the registry and PROMs used in a particular country. European quality five-dimension health survey–three level (EQ-5D-3L), European quality five-dimensional health survey–five level (EQ-5D-5L), 36-item Short Form Health Survey (SF-36), 12-item Short Form Health Survey (SF-12), and Patient-Reported Outcomes Measurement Information System (PROMIS) have all been used in general functional improvement assessment. The Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), University of California Los Angeles (UCLA) activity score, and Visual Analog Scale (VAS) for pain are used in the focused assessment of knee functional outcome. The 2011 Knee Society Score (KSS) included patient expectation and functional activity in addition to information that has to be assessed by the clinician, which was an improvement from its previous version. Although useful for patient counseling, synthesizing information from registry data represents a challenge as a different indexes are used by different registries. The New Zealand (NZOA) Joint Registry has 20-year patient satisfaction data measured by Oxford-12 Knee Score scale from 0 to 48, and the data are categorized as excellent outcomes (>41), good outcomes (34–41), fair outcomes (27–33), and poor outcome (<27). Table 13.1 summarizes the serial outcomes using the OKS.
Table 13.1
Twenty-Year Satisfaction Outcome Using the Oxford Knee Score
| Time | 6 months | 5 years | 10 years | 15 years | 20 years |
|---|---|---|---|---|---|
| Number of patients | 29,816 | 11,768 | 6572 | 2364 | 128 |
| Excellent or good outcomes | 75% | 84% | 82% | 79% | 75% |
| Average score | 37.65 | 40.5 | 39.96 | 39.39 | 39.04 |
The American Joint Replacement Registry has shown that 88.5% of patients at 1-year postoperative follow-up had meaningful improvement in KOOS score. During 2017, the Swedish Knee Arthroplasty Registry demonstrated that 87% of patients at 1-year follow-up were very satisfied or satisfied with TKA as assessed by the VAS. In a study of satisfaction using OKS at 1 year postsurgery in 10,000 patients who underwent surgery in England and Wales the National Joint Registry noted that 81.8% (6625 of 8095) were satisfied, 11.2% (904 of 8095) were unsure, and 7.0% (566 of 8095) were not satisfied.
In a systematic review of 208 studies and 95,560 patients Kahlenberg et al. determined that the median reported percentage of satisfied patients was 88.9%. The same study also showed that the most commonly reported predictor of satisfaction was a higher absolute postoperative patient-reported functional score. Preoperative anxiety and/or depression was the most common preoperative predictor of dissatisfaction, and persistent pain was the most common postoperative predictor of dissatisfaction. Certain activities are easier than others in the postoperative period. In a study by Bourne et al. using WOMAC scoring for pain relief in 1703 patients 72% were satisfied with their ability to go up or down stairs compared with 85% with walking on a flat surface and 84% with sitting or lying. For restored function, patients were least satisfied with getting in or out of a bus or car (70%) and ascending stairs (73%) compared with rising from a bed (82%), lying in a bed (84%), and performing light domestic duties (83%). For overall satisfaction, which was used as the proxy for the satisfaction outcome, 81% (1375) of patients claimed that they were satisfied or very satisfied and 19% (328) were very dissatisfied, dissatisfied, or neutral. The same study also showed that the strongest contributing variables to patient dissatisfaction after primary TKA using odds ratios (ORs) were expectations not met (10.79), a low 1-year WOMAC (2.59), a low preoperative WOMAC pain score while sitting or lying (2.49), and a complication requiring hospital admission (1.99).
With the available data, it is safe to say that 75% to 89% of patients are satisfied after TKA. It has also been shown that expectations not being met is a critical factor in the lack of postoperative satisfaction, and presurgical discussion should include clear goal setting of achievable objectives.
Cost-Effectiveness
Many patients are worried about the cost-effectiveness and QOL improvement in financial terms concerning TKA. Many studies are looking into the cost-effectiveness of TKA and have concluded that TKA is a cost-effective surgery in improving QOL. A study by Losina et al. showed an incremental cost of $18,300 per quality-adjusted life year gained, and they concluded that TKA is a highly cost-effective procedure for the management of end-stage knee osteoarthritis (OA) among Medicare-aged persons compared with nonoperative management. In a systematic review of 23 studies Kamaruzaman et al. concluded that TKA and total hip arthroplasty are cost-effective and should be recommended for the management of patients with end-stage knee and hip OA. Surgeons can convey to their patients that TKA is a cost-effective surgical procedure to improve QOL.
Complications
In 2013 the Knee Society TKA Complications Workgroup published a list of 22 important complications that have a bearing on the outcome of TKA. They can be classified as relating to the surgical procedure, to certain processes, and to the property of the materials used ( Table 13.2 ). This classification helps not only with patient communication regarding the rationale for complications but also with the possible strategies to minimize them. Certain complications such as neurovascular injury, ligament injury, and extensor mechanism disruption are operator-dependent and can be reduced by strict attention to detail.
Table 13.2
Common Complications After Total Knee Arthroscopy
| Procedure (Intraoperative) | Process (Medium to Long Term) | Property (Mechanical Factors) |
|---|---|---|
| Bleeding | Instability and dislocations | Osteolysis |
| Wound complications | Malalignment | Loosening |
| Nerve (0.79%) and vessel injury (0.08%) | Stiffness | Wear |
|
Periprosthetic fracture | |
| Deep venous thrombosis | ||
| Extensor mechanism disruption (0.17%–2.5%) | ||
| Reoperation, revision, readmission | ||
| Infection | ||
| Death |
Nerve and Vessel Injury
Nerve and vessel injury can be caused by direct injury, pressure effect, or secondary damage. Patients who have preexisting flexion or valgus deformity, prolonged tourniquet usage, or rheumatoid arthritis are at increased risk for nerve palsy, primarily of the peroneal nerve. Jacob et al. found that the majority (62%) of neurological deficits completely resolved during the median follow-up of 5.1 years, with an additional 36% of patients reporting partial recovery.
Vascular injuries are a rare but devastating complication of TKA. The popliteal vessels are vulnerable to excessive manipulation, direct injury during bony cuts and during posterior midline soft tissue dissection, and cement polymerization. In a large population database study by Lin et al. there were 15 direct vascular injuries in 111,497 patients, and the primary risk factor was surgeon volume; there was a higher risk of injury in procedures performed by surgeons with lower volume.
Extensor Mechanism Complications
The extensor mechanism complications can include quadriceps tendon and patellar tendon rupture, patellar or tibial tuberosity fracture, or subluxation of the patellofemoral joint. Extensor mechanism rupture can occur in 0.17% to 2.5% of cases as seen in a study by Schoderbek et al. Extensor mechanism disruption is a difficult problem with complicated surgical solutions. The risk factors that predispose to the extensor mechanism dysfunction are inflammatory joint disease, diabetes mellitus, hyperthyroidism, and repeated corticosteroid injections into the knee joint.
Bleeding
Bleeding is a well-known side effect of TKA. With transfusion rates varying from 2.5% to 35.3%, significant postoperative anemia can warrant a blood transfusion. Postoperative allogeneic blood transfusion (ALBT) has been shown to be associated with an increased incidence of early postoperative confusion (OR = 3.44), cardiac arrhythmia (OR = 5.90), urinary catheterization (OR = 1.60), incidence of deep infection (OR = 4.03), and mortality (OR = 2.35). Anemia in the postoperative period is not a benign condition and has the potential to be preventable and correctable. Strategies available are listed in Table 13.3 . Of all the surgical strategies, intraarticular and intravenous (IV) tranexamic acid (TXA) has been known to significantly reduce blood loss. In a systematic review it was found that TXA reduced total blood loss by a mean of 591 mL.
Table 13.3
Anemia Prevention Strategies in Total Knee Arthroscopy
| Iron deficiency anemia |
|
| Intraoperative blood loss |
|
| Postoperative blood loss |
|
Wound Complications
The knee is a superficially located joint with minimal soft tissue covering. In a study by Galat et al. 59 out of 17,784 patients required surgical intervention within 30 days of TKA. More importantly, the need for immediate surgical intervention increased the subsequent need for surgeries by 8 to 10 times. Diabetes, obesity, presurgical albumin <3.5 g/dL, and anemia all increase the risk of superficial surgical site infection (SSI).
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