D. Alex Stroh

Chronic Opioid Use Prior to Total Knee Arthroplasty

BACKGROUND Chronic use of opioid medications may lead to dependence or hyperalgesia, both of which might adversely affect perioperative and postoperative pain management, rehabilitation, and clinical outcomes after total knee arthroplasty. The purpose of this study was to evaluate patients who underwent total knee arthroplasty following six or more weeks of chronic opioid use for pain control and to compare them with a matched group who did not use opioids preoperatively. METHODS Forty-nine knees in patients who had a mean age of fifty-six years (range, thirty-seven to seventy-eight years) and who had regularly used opioid medications for pain control prior to total knee arthroplasty were compared with a group of patients who had not used them. Length of hospitalization, aseptic complications requiring reoperation, requirement for specialized pain management, and clinical outcomes were assessed for both groups. RESULTS Knee Society scores were significantly lower in the patients who regularly used opioid medications at the time of final follow-up (mean, three years; range, two to seven years); the opioid group had a mean of 79 points (range, 45 to 100 points) as compared with a mean of 92 points (range, 59 to 100 points) in the non-opioid group. A significantly higher prevalence of complications was seen in the opioid group, with five arthroscopic evaluations and eight revisions for persistent stiffness and/or pain, compared with none in the matched group. Ten patients in the opioid group were referred for outpatient pain management, compared with one patient in the non-opioid group. CONCLUSIONS Patients who chronically use opioid medications prior to total knee arthroplasty may be at a substantially greater risk for complications and painful prolonged recoveries. Alternative non-opioid pain medications and/or earlier referral to an orthopaedic surgeon prior to habitual opioid use should be considered for patients with painful degenerative disease of the knee.

Reduced dislocation rates and excellent functional outcomes with large-diameter femoral heads.

The purpose of this study was to compare the dislocation rates, functional outcomes, and radiographic results between large- and small-diameter femoral head components. A total of 225 patients (248-hips) who received total hip arthroplasties with large-diameter components (36mm or greater) were compared to 501 patients (559-hips) who received smaller diameter components (less than 36mm). Rates of dislocation and revision, Harris hip score, radiographic findings, and complications were compared between the groups. At a mean follow-up of approximately 5years, a significantly higher rate of dislocation was noted in the small-diameter group (10 of 559) compared to the large-diameter group (0 of 248). The overall implant survivorship, mean Harris hip scores, complication rates, and radiographic outcomes were similar for the two groups. The authors believe that large-diameter components significantly reduced the risk of dislocation in susceptible patients, while preserving good to excellent functional outcomes.

Dual-mobility bearings: a review of the literature

Dislocation after total hip arthroplasty remains a major problem and hip instability is the most common reason for revision. These complications are costly to both patients and the healthcare system, and efforts to reduce them have had varied degrees of success. Although there are well documented patient and surgical risk factors for dislocation, the typical surgical solutions offered (constrained liners, large femoral heads) have the drawbacks of reduced range-of-motion and high rates of revision. Dual-mobility prostheses (unconstrained tripolar prostheses) are hip design solutions to dislocation that aim to provide a greater stability with an increased range-of-motion, along with potentially reduced wear. The mean overall dislocation rate from multiple combined studies using dual-mobility prostheses was 0.1% for primary total hip arthroplasty and 3.5% for revisions, compared with 2–7% for standard primary total hip arthroplasties and up to 16% for revisions. Dual-mobility prostheses offer a viable option for treating recurrent dislocation as well as for primary and revision arthroplasty.

A Comparison of Subvastus and Midvastus Approaches in Minimally Invasive Total Knee Arthroplasty

BACKGROUND The mini-subvastus and the mini-midvastus approaches are among the most common alternatives to the medial parapatellar approach for total knee arthroplasty. The purpose of this study was to compare the early clinical outcomes of these two approaches. METHODS In this prospective, randomized study of fifty-one patients who underwent bilateral total knee arthroplasty, the mini-subvastus approach was used in one knee and the mini-midvastus approach, in the contralateral knee. There were forty-two women and nine men who had a mean age of seventy years at the time of the index arthroplasties, and they were followed for two years postoperatively. Clinical outcome was assessed and compared with use of the Knee Society pain and function scores, the straight-leg-raising test, range of motion, and isokinetic strength testing. Operating time and blood loss for each approach were also compared. In addition, patients were surveyed concerning which knee they preferred. RESULTS Comparisons of postoperative Knee Society scores between both approaches at the time of the two-year follow-up did not yield a significant difference in outcome. Isokinetic strength testing at twelve weeks postoperatively revealed no significant differences in muscle strength, with a mean extensor peak torque-to-body weight ratio of 0.14 Nm/kg for both groups. No significant difference was found with respect to total blood loss, straight-leg-raising test, range of motion, or patient preference. There was no clinically relevant difference in operative times between the two approaches. CONCLUSIONS The minimally invasive subvastus and midvastus approaches for total knee arthroplasty were both associated with excellent short-term clinical results. Some surgeons believe that the subvastus approach completely avoids damage to the quadriceps mechanism and therefore would be associated with improved muscle function. This prospective series did not identify a substantive difference between the two approaches. We believe that the decision between these surgical approaches should be based on surgeon preference and experience.

Should Gram Stains Have a Role in Diagnosing Hip Arthroplasty Infections

BackgroundThe utility of Gram stains in diagnosing periprosthetic infections following total hip arthroplasty has recently been questioned. Several studies report low sensitivity of the test, and its poor ability to either confirm or rule out infection in patients undergoing revision total hip arthroplasty. Despite this, many institutions including that of the senior author continue to perform Gram stains during revision total hip arthroplasty.Questions/purposesWe assessed the sensitivity, specificity, accuracy, and positive and negative predictive values of Gram stains from surgical-site samplings taken from procedures on patients with both infected and aseptic revision total hip arthroplasties.MethodsA review was performed on patients who underwent revision total hip arthroplasty between 2000 and 2007. Eighty-two Gram stains were performed on patients who had infected total hip arthroplasties and underwent revision procedures. Additionally, of the 410 revision total hip arthroplasties performed on patients who were confirmed infection-free, 120 Gram stains were performed. Patients were diagnosed as infected using multiple criteria at the time of surgery. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated from these Gram stain results.ResultsThe Gram stain demonstrated a sensitivity and specificity of 9.8% and 100%, respectively. In this series, the Gram stain had a negative predictive value of 62%, a positive predictive value of 100%, and an accuracy of 63%.ConclusionsGram stains obtained from surgical-site samples had poor sensitivity and poor negative predictive value. Based on these findings, as well as those of other authors, we believe that Gram stains should no longer be considered for diagnosing infections in revision total hip arthroplasty.Level of EvidenceLevel III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Risk of dislocation using large- vs. small-diameter femoral heads in total hip arthroplasty

BackgroundDislocation remains a difficult problem in total hip arthroplasty. Large-diameter femoral heads may lower the incidence of dislocation by enhancing the jump distance and decreasing impingement, but their performance against small-diameter heads has not been assessed. This study compared the mid-term radiographic and functional outcomes of two matched cohorts of patients undergoing total hip arthroplasty who had a high pre-operative risk for dislocation and who received either small-diameter (26- or 28-millimeters) or large-diameter (≥36-millimeters) femoral heads.MethodsAll patients who received large-diameter heads (≥36-millimeter) between 2002 and 2005, and who had pre-operative risk factors for dislocation, were identified in the institution’s joint registry. Forty-one patients (52 hips) who received large-diameter heads were identified, and these patients were matched to 48 patients (52 hips) in the registry who received small-diameter femoral heads.ResultsAt mean final follow-up of 62 months (range, 49 to 101 months), both groups achieved excellent functional outcomes as measured by Harris Hip scores, with slightly better final scores in the large-diameter group (90 vs. 83 points). No patient showed any radiographic signs of loosening. No patient dislocated in the large-diameter femoral head group; the smaller-diameter group had a greater rate of dislocation (3.8%, 2 out of 52).ConclusionsLarge-diameter femoral head articulations may reduce dislocation rates in patients who have a high pre-operative risk for dislocation while providing the same functional improvements and safety as small-diameter bearings.

Gram stains have limited application in the diagnosis of infected total knee arthroplasty

BACKGROUND The diagnosis of periprosthetic knee infections can present a challenge to surgeons, especially in the case of chronic presentation. Gram stains are regularly performed as part of the microbiological evaluation of suspected infected total knee arthroplasties. Recently, the utility of this test in diagnosing infections has been questioned. The purpose of this study was to assess the effectiveness of Gram stains performed from surgical site samples by comparing their results to the final diagnosis of infection. METHODS The results of 347 Gram stains performed at a single center at the time of revision total knee arthroplasty for both septic and aseptic reasons were compared to the final diagnosis based on intra-operative findings and histological evaluation. RESULTS Gram staining demonstrated a low sensitivity of 7% (95% confidence interval 4-12%), a specificity of 99% (95% confidence interval 97-100%), and positive and negative predictive values of 92% and 57%, respectively. CONCLUSIONS This study confirmed previous findings of the poor utility of this test for the diagnosis of periprosthetic knee infections. The authors recommend that Gram staining no longer be performed at the time of suspected periprosthetic knee arthroplasty infection.

How Do Frozen and Permanent Histopathologic Diagnoses Compare for Staged Revision After Periprosthetic Hip Infections

Histopathologic analysis of frozen tissue samples is used to aid the intraoperative diagnosis of periprosthetic hip infections, but there are concerns about reliability. The purposes of this study were to determine the rate of concordance between diagnoses of infection made with frozen and permanent sections and to assess how discrepancies affected patient outcomes. A total of 282 samples from 62 patients were collected for frozen and permanent section analysis. There was concordance in 274 samples (97%). In 1 case, discrepancies led to retention of components during persistent infection, and the patient required further revision and antibiotics until infection free. Otherwise, discrepancies did not affect patient outcomes. There is good concordance between frozen and permanent sections for diagnosing periprosthetic hip infection and rarely do these discrepancies affect management.

Discrepancies between frozen and paraffin tissue sections have little effect on outcome of staged total knee arthroplasty revision for infection.

BACKGROUND Intraoperative analysis of frozen tissue samples has been used to diagnose periprosthetic joint infection in revision total knee arthroplasty, but the precision and reliability of this test throughout staged revision arthroplasty have not been well characterized. We undertook this study to determine the rate of discrepancy between frozen and permanent histopathologic samples in the diagnosis of periprosthetic infection at both the index total knee arthroplasty revision procedure and the attempted reimplantation. METHODS Seventy-six patients who underwent staged revision of a total knee arthroplasty for apparent infection had samples for frozen and permanent sections obtained at both the index revision procedure and subsequent reimplantation attempts. We investigated the rate of discrepancy between these frozen and permanent sections. The clinical and radiographic outcomes of patients with and without concordance between the frozen and permanent sections were reviewed. RESULTS Concordance was noted between 297 (97.7%) of the 304 frozen sections and the permanent sections. Seven discrepancies between diagnoses based on frozen and permanent sections were noted; however, additional samples in these patients were positive and management was not affected. Fewer discrepancies were found during the initial revision procedure (one of 92, 1%) compared with reimplantation (six of 212, 3%). The mean time to reimplantation was similar between patients with and without a discrepancy in diagnosis between the frozen and permanent sections (185 compared with 157 days). The rate of discrepancy between frozen and permanent histopathologic sections was low, and no discrepancy affected the final outcome of any patient. CONCLUSIONS The rate of discrepancy between frozen and permanent histopathologic samples was low for both index revision and reimplantation procedures. In rare instances of discrepancy, management should be unaffected provided a sufficient number of samples were collected.

Excellent Survivorship With the Use of Proximally Coated Tapered Cementless Stems for Total Hip Arthroplasty in Octogenarians

The use of total hip arthroplasty (THA) continues to grow partially because of the increasing life expectancy of the American population. Whether to use cemented or cementless femoral fixation options in older patients is often debated. The purpose of the present study was to compare the clinical and radiographic outcomes after cementless THA in patients ≥80 years to younger patients. Clinical and radiographic data were gathered on 33 patients (35 hips) all 80 years or older who had undergone proximally coated cementless total hip arthroplasties. Outcomes were compared with a matching group for age, body mass index, and diagnosis, who had undergone the same procedure by the same surgeon at a similar time. Harris hip scores were evaluated pre- and postoperatively, and radiographs were reviewed for evaluation of fixation and stability. At a mean follow-up of 4 years, 97% of the hips (34 of 35) remained unrevised and the mean Harris hip score had improved by 39 points to 83 points (range, 26-100 points). On radiographic evaluation, 91% were found to have full bony ingrowth, with 1 hip having osteolysis of the proximal femur. Mortality was 23% at 86 months. Except for mortality, the outcomes and complication rates were similar to the younger group except that the matching group had higher final postoperative Harris hip scores. Proximally coated tapered cementless THA is a safe and efficacious method for providing good clinical outcomes with low revision rates in patients 80 years of age or older.