Berry, Daniel J

Aims Wear of the polyethylene (PE) tibial insert of total knee arthroplasty (TKA) increases the risk of revision surgery with a significant cost burden on the healthcare system. This study quantifies wear performance of tibial inserts in a large and diverse series of retrieved TKAs to evaluate the effect of factors related to the patient, knee design, and bearing material on tibial insert wear performance. Methods An institutional review board-approved retrieval archive was surveyed for modular PE tibial inserts over a range of in vivo duration (mean 58 months (0 to 290)). Five knee designs, totalling 1,585 devices, were studied. Insert wear was estimated from measured thickness change using a previously published method. Linear regression statistical analyses were used to test association of 12 patient and implant design variables with calculated wear rate. Results Five patient-specific variables and seven implant-specific variables were evaluated for significant association with lower insert wear rate. Six were significant when controlling for other factors: greater patient age, female sex, shorter duration in vivo, polished tray, highly cross-linked PE (HXLPE), and constrained knee design. Conclusion This study confirmed that knee wear rate increased with duration in vivo. Older patients and females had significantly lower wear rates. Polished modular tibial tray surfaces, HXLPE, and constrained TKA designs were device design factors associated with significantly reduced wear rate. Cite this article: Bone Joint J 2021;103-B(11):1695–1701.

Background: Septic arthritis of the native knee often results in irreversible joint damage leading to the need for total knee arthroplasty (TKA). The purpose of the present study was to examine the intermediate-term risk of periprosthetic joint infection (PJI), aseptic revision, and reoperation following primary TKA in patients with a history of septic arthritis of the native knee as compared with primary TKA performed for the treatment of osteoarthritis. Methods: We retrospectively identified 215 primary TKAs performed from 1971 to 2016 at a single institution in patients with a history of septic arthritis of the native knee. Each case was matched 1:1 based on age, sex, body mass index (BMI), and surgical year to a TKA for osteoarthritis. The mean age and BMI were 63 years and 30 kg/m 2 , respectively. The mean duration of follow-up was 9 years. Results: Survivorships free of PJI at 10 years were 90% and 99% for the septic arthritis and osteoarthritis groups, respectively (hazard ratio [HR] = 6.1; p < 0.01). Ten-year survivorships free of any aseptic revisions were 83% and 93% (HR = 2.5; p < 0.01), and survivorships free of any reoperation were 61% and 84% (HR = 2.9; p < 0.01) for the septic arthritis and osteoarthritis groups, respectively. In addition, as time from the diagnosis of native knee septic arthritis to TKA increased, the relative risk of subsequent infection decreased. Preoperative and 2-year postoperative Knee Society scores were similar between the groups (p = 0.16 and p = 0.19, respectively). Conclusions: There was a 6.1-fold increased risk of PJI in patients undergoing TKA with a history of native knee septic arthritis when compared with controls undergoing TKA for the treatment of osteoarthritis, with a cumulative incidence of 9% at 10 years. Subgroup analysis of the septic arthritis cohort revealed a higher risk of any infection in patients who underwent TKA within the first 5 to 7 years after the diagnosis of septic arthritis as compared with those with a greater duration. Moreover, the 10-year rates of survival free of aseptic revision, any revision, and any reoperation were significantly worse in the native knee septic arthritis cohort. Level of Evidence: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Rifampin is an antibiotic with antistaphylococcal biofilm activity used in the management of staphylococcal periprosthetic joint infection with irrigation and debridement with component retention; some patients are unable to receive rifampin due to drug interactions or intolerance. We recently showed rifabutin and rifapentine to have in vitro activity against planktonic and biofilm states of rifampin-susceptible periprosthetic joint infection-associated staphylococci.

AimsThe prevalence of ipsilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA) is rising in concert with life expectancy, putting more patients at risk for interprosthetic femur fractures (IPFFs). Our study aimed to assess treatment methodologies, implant survivorship, and IPFF clinical outcomes.MethodsA total of 76 patients treated for an IPFF from February 1985 to April 2018 were reviewed. Prior to fracture, at the hip/knee sites respectively, 46 femora had primary/primary, 21 had revision/primary, three had primary/revision, and six had revision/revision components. Mean age and BMI were 74 years (33 to 99) and 30 kg/m2(21 to 46), respectively. Mean follow-up after fracture treatment was seven years (2 to 24).ResultsOverall, 59 fractures were classified as Vancouver C (Unified Classification System (UCS) D), 17 were Vancouver B (UCS B). In total, 57 patients (75%) were treated with open reduction and internal fixation (ORIF); three developed nonunion, three developed periprosthetic joint infection, and two developed aseptic loosening. In all, 18 patients (24%) underwent revision arthroplasty including 13 revision THAs, four distal femoral arthroplasties (DFAs), and one revision TKA: of these, one patient developed aseptic loosening and two developed nonunion. Survivorship free from any reoperation was 82% (95% confidence interval (CI) 66.9% to 90.6%) and 77% (95% CI 49.4% to 90.7%) in the ORIF and revision groups at two years, respectively. ORIF patients who went on to union tended to have stemmed knee components and greater mean interprosthetic distance (IPD = 189 mm (SD 73.6) vs 163 mm (SD 36.7); p = 0.546) than nonunited fractures. Patients who went on to nonunion in the revision arthroplasty group had higher medullary diameter: cortical width ratio (2.5 (SD 1.7) vs 1.3 (SD 0.3); p = 0.008) and lower IPD (36 mm (SD 30.6) vs 214 mm (SD 32.1); p < 0.001). At latest follow-up, 95% of patients (n = 72) were ambulatory.ConclusionInterprosthetic femur fractures are technically and biologically challenging cases. Individualized approaches to internal fixation versus revision arthroplasty led to an 81% (95% CI 68.3% to 88.6%) survivorship free from reoperation at two years with 95% of patients ambulatory. Continued improvements in management are warranted. Cite this article: Bone Joint J 2021;103-B(7 Supple B):122–128.

AimsThis study aimed to determine outcomes of isolated tibial insert exchange (ITIE) during revision total knee arthroplasty (TKA).MethodsFrom 1985 to 2016, 270 ITIEs were performed at one institution for instability (55%, n = 148), polyethylene wear (39%, n = 105), insert fracture/dissociation (5%, n = 14), or stiffness (1%, n = 3). Patients with component loosening, implant malposition, infection, and extensor mechanism problems were excluded.ResultsSurvivorship free of any re-revision was 68% at ten years. For the indication of insert wear, survivorship free of any re-revision at ten years was 74%. Re-revisions were more frequent for index diagnoses other than wear (hazard ratio (HR) 1.9; p = 0.013), with ten-year survivorships of 69% for instability and 37% for insert fracture/dissociation. Following ITIE for wear, the most common reason for re-revision was aseptic loosening (33%, n = 7). For other indications, the most common reason for re-revision was recurrence of the original diagnosis. Mean Knee Society Scores improved from 54 (0 to 94) preoperatively to 77 (38 to 94) at ten years.ConclusionAfter ITIE, the risk and reasons for re-revision correlated with preoperative indications. The best results were for polyethylene wear. For other diagnoses, the re-revision rate was higher and the failure mode was most commonly recurrence of the original indication for the revision TKA. Cite this article: Bone Joint J 2021;103-B(6):1103–1110.

AimsIt remains difficult to diagnose early postoperative periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). We aimed to validate the optimal cutoff values of ESR, CRP, and synovial fluid analysis for detecting early postoperative PJI in a large series of primary TKAs.MethodsWe retrospectively identified 27,066 primary TKAs performed between 2000 and 2019. Within 12 weeks, 169 patients (170 TKAs) had an aspiration. The patients were divided into two groups: those evaluated ≤ six weeks, or between six and 12 weeks postoperatively. The 2011 Musculoskeletal Infection Society (MSIS) criteria for PJI diagnosis in 22 TKAs. The mean follow-up was five years (two months to 17 years). The results were compared using medians and Mann-Whitney U tests and thresholds were analyzed using receiver operator characteristic curves.ResultsWithin six weeks, the median CRP (101 mg/l vs 35 mg/l; p = 0.011), synovial WBCs (58,295 cells/μl vs 2,121 cells/μl; p ≤ 0.001), percentage of synovial neutrophils (91% vs 71% (p < 0.001), and absolute synovial neutrophil count (ANC) (50,748 cells/μl vs 1,386 cells/μl (p < 0.001) were significantly higher in infected TKAs. Between six and 12 weeks, the median CRP (85 mg/l vs 5 mg/l (p < 0.001)), ESR (33 mm/hr vs 14 mm/hr (p = 0.015)), synovial WBCs (62,247 cells/μl vs 620 cells/μl (p < 0.001)), percentage of synovial neutrophils (93% vs 54% (p < 0.001)), and ANC (55,911 cells/μl vs 326 cells/μl (p < 0.001)) were also significantly higher in infected TKAs. Optimal thresholds at ≤ six weeks were: CRP ≥ 82 mg/l (sensitivity 70%, specificity 77%), synovial WBCs ≥ 8,676 cells/μl (83%, 90%), percentage of synovial neutrophils ≥ 88% (67%, 78%), and ANC ≥ 8,346 cells/μl (83%, 91%). Between six and 12 weeks, thresholds were: CRP ≥ 34 mg/l (90%, 93%), synovial WBCs ≥ 1,983 cells/μl (80%, 85%), percentage of synovial neutrophils ≥ 76% (80%, 81%), and ANC ≥ 1,684 cells/μl (80%, 87%).ConclusionEarly PJI after TKA should be suspected within six weeks if the CRP is ≥ 82 mg/l, synovial WBCs are ≥ 8,676 cells/μl, the percentage of synovial neutrophils is ≥ 88%, and/or the ANC is ≥ 8,346 cells/μl. Between six and 12 weeks, thresholds include a CRP of ≥ 34 mg/l, synovial WBC of ≥ 1,983 cells/μl, a percentage of synovial neutrophils of ≥ 76%, and/or an ANC of ≥ 1,684 cells/μl. Cite this article: Bone Joint J 2021;103-B(6 Supple A):177–184.

Background: Most North American surgeons predominantly use uncemented stems in primary total hip arthroplasties (THAs) and reserve cemented stems for selected older patients and those with poor bone quality. However, data on this “selective use” strategy for cemented stems in the population at risk for periprosthetic fracture and implant loosening are limited. The purpose of this study was to describe implant survivorship, complications, and radiographic results of a specific collarless, polished, tapered cemented stem (Exeter; Stryker) used selectively in a predominantly elderly population undergoing primary THA. Methods: We identified 386 patients who underwent a total of 423 primary THAs with selectively utilized Exeter stems for the treatment of osteoarthritis between 2006 and 2017. In the same time period, 11,010 primary THAs were performed with uncemented stems and 961 with non-Exeter cemented stems. The mean patient age was 77 years, 71% were female, and the mean body mass index was 29 kg/m 2 . Competing risk analysis accounting for death was utilized to determine cumulative incidences of revision and reoperation. The mean follow-up was 5 years (range, 2 to 12 years). Results: The 10-year cumulative incidence of any femoral component revision in this patient cohort was 4%, with 10 stems revised at the time of the latest follow-up. There were no intraoperative femoral fractures. The indications for revision were postoperative periprosthetic femoral fracture (n = 6), dislocation (n = 3), and infection (n = 1). There were no revisions for femoral loosening. The 10-year cumulative incidence of reoperation was 10%. The 10-year cumulative incidence of Vancouver B periprosthetic femoral fracture was 2%. Radiographically, there were no cases of aseptic loosening or osteolysis. There was a significant improvement in median Harris hip score, from 53 preoperatively to 92 at a mean follow-up of 5 years (p < 0.001). Conclusions: The strategy of selectively utilizing a collarless, polished, tapered cemented stem produced a low (4%) cumulative incidence of stem revision at 10 years postoperatively and resulted in no cases of aseptic loosening. The use of the Exeter stem did not eliminate postoperative femoral fractures in this predominantly elderly, female patient population. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

AbstractExperimental analyses of posttraumatic knee arthrofibrosis utilize a rabbit model as a gold standard. However, a rodent model of arthrofibrosis offers many advantages including reduced cost and comparison with other models of organ fibrosis. This study aimed to characterize the biomechanical, histological, and molecular features of a novel posttraumatic model of arthrofibrosis in rats. Forty eight rats were divided into two equal groups. An immobilization procedure was performed on the right hind limbs of experimental rats. One group was immobilized for 4 weeks and the other for 8 weeks. Both groups were remobilized for 4 weeks. Limbs were studied biomechanically via assessment of torque versus degree of extension, histologically via whole knee specimen, and molecularly via gene expression of posterior capsular tissues. Significant differences were observed between experimental and control limbs at 4 N‐cm of torque in the 4‐week (knee extension: 115° ± 8° vs. 169° ± 17°, respectively; p = 0.007) and 8‐week immobilization groups (knee extension: 99° ± 12° vs. 174° ± 9°, respectively; p = 0.008). Histologically, in each group experimental limbs demonstrated increased posterior capsular thickness and total area of tissue when compared to control limbs (p < 0.05). Gene expression values evaluated in each group were comparable. This study presents a novel rat model of arthrofibrosis with severe and persistent knee contractures demonstrated biomechanically and histologically. Statement of clinical significance: Arthrofibrosis is a common complication following contemporary total knee arthroplasties. The proposed model is reproducible, cost‐effective, and can be employed for translational investigations studying the pathogenesis of arthrofibrosis and efficacy of neoadjuvant pharmacologic agents.

Background: Two-stage exchange arthroplasty with a high-dose antibiotic-loaded bone cement (ALBC) spacer and intravenous or oral antibiotics is the most common method of managing a periprosthetic joint infection (PJI) after a total knee arthroplasty (TKA). However, little is known about the contemporary incidence, the risk factors, and the outcomes of acute kidney injuries (AKIs) in this cohort. Methods: We identified 424 patients who had been treated with 455 ALBC spacers after resection of a PJI following a primary TKA from 2000 to 2017. The mean age at resection was 67 years, the mean body mass index (BMI) was 33 kg/m 2 , 47% of the patients were women, and 15% had preexisting chronic kidney disease (CKD). The spacers (87% nonarticulating) contained a mean of 8 g of vancomycin and 9 g of an aminoglycoside per construct (in situ for a mean of 11 weeks). Eighty-six spacers also had amphotericin B (mean, 412 mg). All of the patients were concomitantly treated with systemic antibiotics for a mean of 6 weeks. An AKI was defined as a creatinine level of ≥1.5 times the baseline or an increase of ≥0.3 mg/dL within any 48-hour period. The mean follow-up was 6 years (range, 2 to 17 years). Results: Fifty-four AKIs occurred in 52 (14%) of the 359 patients without preexisting CKD versus 32 AKIs in 29 (45%) of the 65 patients with CKD (odds ratio [OR], 5; p = 0.0001); none required acute dialysis. Overall, when the vancomycin concentration or aminoglycoside concentration was >3.6 g/batch of cement, the risk of AKI increased (OR, 1.9 and 1.8, respectively; p = 0.02 for both). Hypertension (β = 0.17; p = 0.002), perioperative hypovolemia (β = 0.28; p = 0.0001), and acute atrial fibrillation (β = 0.13; p = 0.009) were independent predictors for AKI in patients without preexisting CKD. At the last follow-up, 8 patients who had sustained an AKI had progressed to CKD, 4 of whom received dialysis. Conclusions: In our study, the largest series to date that we are aware of regarding this issue, AKI occurred in 14% of patients with normal renal function at baseline, and 2% developed CKD after undergoing a 2-stage exchange arthroplasty for a PJI after TKA. However, the risk of AKI was fivefold greater in those with preexisting CKD. The causes of acute renal blood flow impairment were independent predictors for AKI. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.