Total joint arthroplasty represents one of the greatest advances in modern orthopaedic surgery and continues to be one of the safest and the most effective surgical procedures. Nevertheless, hip and knee arthroplasty have been associated with several serious potential complications and occasionally even with death1-4.
Recent improvements in surgical and anesthesia techniques have contributed to a marked reduction in mortality after elective joint arthroplasty3,4. However, because modern medical care results in longer life expectancy in general and in better survival of patients with cardiac and other systemic illnesses in particular, joint arthroplasty is being performed in sicker patients. Hence, it is plausible that orthopaedic surgeons may observe a higher prevalence of medical complications in their patients who have elective joint arthroplasty.
The latter, if true, would imply that better preoperative medical optimization and stringent, perhaps longer, postoperative surveillance of these patients are required. In contrast, with the surge in minimally invasive joint arthroplasty5-13, the decline in reimbursement, and patients' expectation for faster recovery, a worrisome trend for shorter hospital stays has been emerging.
This prospective study was designed to elucidate the incidence, timing, and the severity of complications that may occur following elective primary unilateral total joint arthroplasty in the lower extremity. Furthermore, we sought to specifically explore the nature of these complications with the intention of identifying patients who may be at risk.
Materials and Methods
All patients undergoing elective primary or revision total hip or knee arthroplasty at our institution from July 2004 to July 2005 were recruited into the study. Institutional review board approval was obtained for the study. During this period, a total of 2391 hip and knee reconstructive procedures had been performed in 2183 patients, and 2048 of the procedures were total joint arthroplasties done in 1842 patients. This included 1056 primary total hip arthroplasties in 1011 patients, 992 primary total knee arthroplasties in 831 patients, 198 revision total hip arthroplasties, and 120 revision total knee arthroplasties. The primary joint arthroplasties had been performed in 732 male patients with a mean age of sixty-two years (range, fifteen to ninety-one years) and 1110 female patients with a mean age of sixty-six years (range, seventeen to ninety-seven years). This study includes only patients undergoing primary unilateral total joint arthroplasty.
All patients who underwent elective joint arthroplasty at our institution completed preoperative evaluation forms that captured detailed data including demographic information, past medical and surgical history, medication history, and the functional status.
A standardized and detailed form intended to capture all medical and orthopaedic complications was devised. This form was completed on a daily basis for every patient who underwent elective joint arthroplasty. The hospital course of the patients was followed very closely, and any complications identified by the treating internist or evident on a laboratory test or other investigations were recorded. The details of any medical or surgical intervention were also noted.
Course After Discharge
During the first postoperative visit, occurring usually at six weeks, the postoperative evaluation forms completed by the patient were collected. A form for capturing any complications that may have happened following discharge was also completed by the examining physician. The circumstances leading to the complications, if any, and the details of the therapeutic intervention for each complication were recorded. As part of routine surveillance, patients who did not return for scheduled follow-up appointments were contacted by means of a detailed questionnaire sent by mail and then by a telephone call, if necessary. The mean duration of follow-up for the patients in this cohort was ninety-two days (range, sixty to 420 days).
Regional anesthesia, unless it was contraindicated, was used for all patients who had elective arthroplasty. All hip arthroplasties were performed through an anterolateral approach with the patient in the supine position. All total knee arthroplasties were performed through a medial parapatellar arthrotomy. All operations were performed by or under the close supervision of one of five arthroplasty surgeons. Joint replacements were carried out in a laminar flow room with all members of the surgical team wearing body-exhaust suits during surgery. All patients in this cohort received uncemented total hip replacements. All patients who had a primary hip arthroplasty were allowed to walk postoperatively using a walking aid with weight-bearing as tolerated.
All patients were followed closely by an internist. Patients deemed to be at high risk of cardiovascular complications postoperatively were routinely admitted to the intensive care unit or a step-down unit with continuous electrocardiogram monitoring and dedicated nursing care. For other patients, monitoring of the respiratory rate, heart rate, blood pressure, and pulse oximetry was carried out at frequent intervals by the nursing staff. Any changes in these parameters that were deemed to be clinically important were investigated. Daily laboratory tests, including complete blood-cell count, renal function tests, blood chemistry, prothrombin time, and international normalized ratio, were performed. Additional tests, such as liver function tests, troponin levels, chest radiographs, electrocardiograms, and computerized tomography, were also ordered as deemed necessary for some patients.
Thromboembolic prophylaxis, namely low-dose Coumadin (warfarin) (with a goal of an international normalized ratio in the range of 1.5 to 2.0) for six weeks, was administered to all patients unless contraindicated. Intravenous antibiotics, usually a first-generation cephalosporin, were administered preoperatively and for twenty-four hours following the surgery.
Definition of Complications
The complications were categorized into systemic and local. Furthermore, the complications were subcategorized as major systemic if they were deemed to be life-threatening and required complex medical intervention, such as transfer to the intensive care unit, or as major local if the complication necessitated additional surgical intervention or was deemed to result in temporary or permanent functional impairment. Minor complications were those that resulted in a prolonged hospital stay, necessitated additional observation such as monitoring of the wound, or required additional medical treatment such as blood transfusion or antibiotics.
Myocardial infarction was determined on the basis of an increase in the troponin level and/or electrocardiographic changes. Acute renal failure was defined as an abrupt decline in renal function parameters (increasing creatinine) with reduced urine output. Pulmonary embolus was diagnosed on the basis of the presence of emboli in the pulmonary vasculature as determined by multidetector computerized tomography. Anemia was thought to exist if the postoperative hemoglobin level of the patient, regardless of the preoperative hemoglobin level, had declined to <10 mg/dL. Persistent wound drainage was defined as any degree of drainage from the wound more than forty-eight hours after the index surgery. Deep venous thrombosis was diagnosed with use of Doppler ultrasound and was categorized into distal and proximal clots.
Descriptive statistics and the Fisher exact test were used for analysis of categorical data. Continuous data were analyzed with use of descriptive statistics and the non-paired t test. Univariate regression analysis was performed on all risk factors for complications. Multiple logistic regression analysis was performed on all variables that were significant in univariate analyses. For the univariate analysis, a p value of < 0.1 was considered significant. For all other tests, a p value of < 0.05 was considered significant. All analyses were performed with use of SPSS software (version 13; SPSS, Chicago, Illinois).
Cause and Time of Death
One patient (0.06%) in the cohort died. The patient had had aspiration pneumonia develop three days after a primary knee arthroplasty and died on the twenty-third postoperative day while in the intensive care unit. Postmortem examination revealed the final cause of death to be cerebral edema secondary to aspiration pneumonia.
Incidence of Medical Complications
There were a total of 104 life-threatening systemic complications (Table I). These included a non-fatal cardiac arrest in one patient, tachyarrhythmia in thirty-three patients, congestive heart failure or pulmonary edema in ten patients, and myocardial infarction in six patients. Four patients had development of severe hypotension that necessitated vasopressor administration and transfer to a monitored bed. The cause of the hypotension in all four patients could not be elicited with certainty, but it was deemed to be cardiac in origin. There were twenty-five confirmed pulmonary emboli. Other complications included acute renal failure in fourteen patients, stroke or a transient ischemic attack in six patients, bowel obstruction in three patients, and pneumothorax in one patient. A total of 353 minor systemic complications, mostly related to anemia, also occurred in this cohort.
Incidence of Orthopaedic Complications
There were seventeen major and ninety-nine minor orthopaedic complications. Surgical intervention to address the complications was required in eleven patients and included leg fasciotomy following vascular injury (two patients), embolectomy (two patients), open reduction and internal fixation of periprosthetic fractures (two patients), and operative incision and drainage (five patients).
Timing of Complications
Ninety-four of the life-threatening medical complications occurred within four days of the index surgery (Fig. 1). The mean length of the hospital stay for the entire cohort was 3.9 days (range, one to thirty-six days) and 4.7 days (range, two to thirty-six days) for the patients who had complications (p < 0.001). There was one major complication (stroke) that occurred following discharge of the patient from the hospital.
Risk Factors for Major Complications
A number of factors were analyzed with respect to their potential influence on the development of major medical complications (Table II). Univariate analysis identified older age; a higher body-mass index; general anesthesia; and medical comorbidi-ties, as measured by the American Society of Anesthesiology (ASA) score, to be important predictors of postoperative major complications. When these factors were subjected to multiple logistic regression analysis, age (odds ratio, 1.21; 95% confidence interval, 1.02 to 1.19), body mass index (odds ratio, 1.01; 95% confidence interval, 0.99 to 1.09), and ASA score (odds ratio, 0.76; 95% confidence interval, 0.55 to 1.2) were found to be important predictors of major complications.
There were a total of ten readmissions in the series. The reasons for readmission included wound-related problems in six patients. The reasons for readmission for medical complications included deep-vein thrombosis in four patients and stroke in one patient. One of the readmitted patients experienced two complications, resulting in a total of eleven complications in these patients.
Substantial and parallel advances in the medical fields over the recent years have enabled a large number of patients with severe illnesses to enjoy longer life expectancy and to seek orthopaedic care for their degenerative joints. Hence, total joint arthroplasty is currently being offered to some patients with serious comorbidities14-16 who may have been deemed inappropriate candidates during the early years of joint replacement. Despite the availability of this surgical procedure to sick and frail patients, the mortality and morbidity following total joint arthroplasty remains very low4. Deaths and complications following joint arthroplasty, however, can and do occur4.
In recent years, minimally invasive surgery has become more popular6,8,13,17,18. The advocates of minimally invasive surgery have cited reduced intraoperative blood loss; less peri-operative pain; faster recovery; better incision cosmesis; and, more importantly, a shorter hospital stay as potential benefits6-8,13,19. The mean length of stay following minimally invasive total hip arthroplasty was reported to be 1.9 days compared with 3.5 days for a standard hip arthroplasty6. Berger and Duwelius proposed a “same day” discharge pathway for patients undergoing two-incision total hip arthroplasty7.
The minimally invasive arthroplasty, with the exception of some inherent differences in soft-tissue dissection, still involves surgical violation of the medullary canal with the potential for fat and marrow embolization14,20,21. Furthermore, patients require the same degree of anesthesia as that needed for conventional joint replacement to allow the surgeon to perform the same bone cuts and insert the same implants as in conventional joint arthroplasty. Hence, any complications associated with a standard joint arthroplasty can conceivably occur after minimally invasive joint replacement. This raises a critical and worrisome concern: what influence does a shorter hospital stay have on the management of life-threatening complications if they were to occur outside the hospital?
This study, which was designed with the intention of identifying in-hospital complications that may occur after elective joint arthroplasty, highlights some important findings. First, it demonstrated that a considerable number of life-threatening medical complications occur in 6% of the patients who have an elective joint arthroplasty. All of these complications were deemed to be life-threatening, as the lack of emergent medical intervention in the form of the administration of drugs and close monitoring could have resulted in catastrophic consequences. Even if one assumes that emergent medical care could have been provided for most of these patients if they were outside the hospital, one cannot overlook the relatively high incidence of cardiac complications in general and near-fatal arrhythmias (ventricular tachycardia) in particular that occurred in these patients. On the basis of the analysis of detailed data, we can confidently say that major complications, if they occurred outside the hospital, would have resulted in the death of twenty to twenty-five patients in this cohort. Another important finding of this study was that for more than half (58%) of the patients who had a major complication, the complication could not have been predicted on the basis of the medical history. Hence, strategies such as close surveillance of so-called at risk patients may not identify other patients who may have life-threatening complications develop for the first time. Furthermore, all of these life-threatening complications occurred despite intensive and rigorous medical evaluation of all patients in this cohort. Finally, the present study demonstrated that the majority (>90%) of the fatal and near-fatal complications occurred during the early days and within the expected typical four-day hospital stay of a standard elective joint replacement (Fig. 1).
The incidence of in-hospital mortality and major complications such as myocardial infarction in our cohort is similar to that in previous reports10,11. Furthermore, the risk factors identified in our study, namely old age and the history of coexistent diseases, also agree with the findings of previous studies10. An additional factor, increased body mass index, was identified as a possible etiological factor for an increased rate of complications. Although one may have intuitively selected any of the aforementioned as possible predisposing factors to systemic complications after total joint arthroplasty, it is important to recall that not all patients with near-fatal complications possessed these risk factors. As far as we know, none of these risk factors have been cited as contraindications for minimally invasive total hip arthroplasty. We deliberately excluded patients who had a revision or bilateral joint arthroplasty since, by strict criteria, they may not be considered as candidates for minimally invasive joint arthroplasty. Hence, any of the complications that were encountered in this cohort could occur in patients undergoing minimally invasive joint replacement.
We invested extensive efforts to ensure that every complication occurring in the hospital and following discharge was captured. Despite the prospective nature of this study, it is possible, although unlikely, that some complications may have escaped detection particularly if they occurred following discharge. The latter, if true, would imply that the actual incidence of complications is higher than what is reported. We believe that the incidence of complications reported in the present study is likely to be affected by other factors. One important fact to consider is that this study was performed in a single, high-volume institution where standardized protocols are in place and patients receive a thorough preoperative medical evaluation and are followed diligently by internists postoperatively. Hence, it is plausible that the incidence of complications would be higher in centers if the aforementioned protocols were not in place. Conversely, the implementation of these protocols, in particular the routine measurement of pulse oximetry and the availability of modern imaging modalities such as multidetector computed tomography scanning, may have resulted in the detection of complications that might have otherwise gone unnoticed. We were also stringent with the definition of some complications such as anemia and wound drainage. The majority of the patients diagnosed as having anemia in this study did not receive a blood transfusion and were asymptomatic. A large number of patients with chronic disease who had a low preoperative hemoglobin level, and despite experiencing a small decrease in the hemoglobin level, were categorized as anemic. Similarly, a large number of patients in this cohort who were classified as having a draining wound would not have been classified as such in other centers. We had selected any drainage from the wound beyond forty-eight hours as the cut-off beyond which drainage was considered abnormal.
Our findings raise concern and caution against the current strategies to reduce hospital length of stay after total reconstruction of a major joint in the lower extremity. ▪
Disclosure: The authors did not receive grants or outside funding in support of their research for or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.
Investigation performed at the Rothman Institute of Orthopedics, Thomas Jefferson University, Philadelphia, Pennsylvania
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