Faculty Bibliography

BACKGROUND:The use of chemoprophylaxis to prevent thromboembolic disease after primary THA and TKA can be associated with postoperative bleeding complications. Mechanical prophylaxis has been studied as an alternative to chemoprophylaxis with greater safety in patients undergoing THA, but no data have been published comparing the safety of chemoprophylaxis versus mechanical methods for patients undergoing TKA. The risk of readmission resulting from bleeding and venous thromboembolism (VTE) has also not been determined for patients undergoing THA or TKA when treated with low-molecular-weight heparin (LMWH) alone compared with mechanical prophylaxis plus aspirin (ASA). QUESTION/PURPOSES:We sought to answer four questions: For the THA and TKA cohorts, respectively, (1) was the incidence of readmission resulting from VTE and bleeding complications higher with LMWH than mobile compression plus ASA; and (2) was the incidence of wound bleeding complications higher with LMWH than mechanical compression plus ASA? For the TKA cohort specifically, (3) was the frequency of systemic bleeding events and complications related to chemical prophylaxis higher with LMWH compared with mechanical compression plus ASA? (4) Was there a difference in symptomatic VTEs between LMWH and mechanical compression plus ASA? METHODS:Between November 2008 and April 2011, 632 patients underwent primary THA and TKA. Seventy-two patients (11%) were identified before surgery as being at high risk for VTE (31 patients) or bleeding (41 patients) and were excluded from the study. Five hundred sixty patients (89%) were considered to be at standard risk for VTE and bleeding and comprise the study cohort. Between November 2008 and November 2009, 252 patients (76 THAs, 176 TKAs) underwent THA and TKA and were treated with LMWH (5 mg dalteparin given subcutaneously daily for 14 days) and in-hospital nonmobile mechanical compression. Between November 2009 and April 2011, a total of 308 patients undergoing THA and TKA (108 THAs, 200 TKAs) were treated using a mobile compression device plus oral aspirin once daily for 2 weeks after surgery. All complications and readmissions that occurred within 6 weeks of surgery were noted. There were no differences between the VTE treatment groups with regard to age, sex, or body mass index. RESULTS:For the THA cohort, there was no difference in the frequency of readmission for a bleeding complication (wound or systemic) between the two groups (2.6% for LMWH versus 0.9% for mobile compression; p = 0.57; odds ratio [OR], 2.9). Patients undergoing TKA treated with LMWH had higher readmission rates within 6 weeks of surgery because of a bleeding complication, a wound infection, or the development of a VTE (6.8% for LMWH versus 1.5% for mobile compression; p = 0.015; OR, 4.8). For the THA cohort, there was higher wound bleeding complication frequency with LMWH (9.2% for LMWH versus 0.9% for mechanical compression; p = 0.009; OR, 10.9). Patients undergoing TKA treated with LMWH had a higher frequency of wound bleeding complications or infection (3.9% for LMWH versus 0.5% for mobile compression; p = 0.028; OR, 8.2). Patients undergoing TKA treated with LMWH had higher rates of systemic bleeding or a complication secondary to LMWH administration (2.8% for LMWH versus 0% for mobile compression; p = 0.022; OR, 12.8). No difference was noted in the rate of symptomatic VTEs between either group (for THA: 2.6% for the LMWH group versus 1.9% for the mechanical compression group; p = 1; for TKA: 1.1% versus 0%, respectively; p = 0.22). CONCLUSIONS:Based on these results, we advocate for routine use of mobile mechanical compression devices in the prevention of VTEs and complications associated with more potent chemical anticoagulants. However, more focused randomized clinical trials are needed to validate these findings. LEVEL OF EVIDENCE:Level III, therapeutic study.

OBJECTIVE:To evaluate the outcomes of a single-stage surgical protocol to treat a presumed aseptic long-bone nonunion with positive intraoperative cultures obtained at the time of surgery. DESIGN/METHODS:Retrospective comparative series. SETTING/METHODS:Orthopaedic specialty hospital. PATIENTS AND METHODS/METHODS:We retrospectively identified 77 patients with long-bone nonunions thought to be aseptic preoperatively, which grew bacteria from cultures obtained at the time of index nonunion surgery. INTERVENTION/METHODS:Fifty (65%) patients underwent open debridement of the nonunion site followed by surgical stabilization through plates and screws. Twenty-seven (35%) patients underwent exchange nailing with canal reamings used for cultures. MAIN OUTCOME MEASUREMENT/METHODS:Rate of radiographic union, time to clinical and radiographic union, nonunion rate after index nonunion surgery, and final union rate after revision procedures. RESULTS:Osseous union after the index nonunion surgery was achieved in 84% of the patients (65 of 77). Time to clinical union was 6.3 months (range, 1-24 months), and time to radiographic union was 7.4 months (range, 2-24 months). Eighteen percent (14 of 77 patients) did not heal after the index nonunion surgery and required additional surgeries. The final union rate after revision surgery was 99% (76 of 77 patients). CONCLUSIONS:Eighty-four percent of presumed aseptic nonunions of long-bone fractures with positive intraoperative cultures fully healed after a single-stage surgical protocol and long-term antibiotic when appropriate. When patients are diagnosed with a subclinical infected nonunion, they should be counseled about the higher likelihood of reoperation, but in most cases can expect excellent union rates after 1 additional surgery. LEVEL OF EVIDENCE/METHODS:Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:Opioids have been the mainstay of treatment in the physiologically young geriatric hip fracture patient undergoing total hip arthroplasty (THA). However opioid-related side effects increase morbidity. Regional anesthesia may provide better analgesia, while decreasing opioid-related side effects. The goal of this study was to examine the effect of perioperative continuous femoral nerve blockade with regards to pain scores, opioid-related side effects and posthospital disposition in hip fracture patients undergoing THA. METHODS:Twenty-nine consecutive geriatric hip fracture patients (22 women/7 men) underwent THA. Average follow-up was 8.3 months (6 weeks-39 months). Fifteen patients were treated with standard analgesia (SA). Fourteen patients received an ultrasound-guided insertion of a femoral nerve catheter after radiographic confirmation of a hip fracture. All complications and readmissions that occurred within 6 weeks of surgery were noted. RESULTS:Continuous femoral nerve catheter (CFNC) patients were discharged home more frequently than SA patients (43% for CFNC vs 7% for SA; P = .023). CFNC patients reported lower average pain scores preoperatively (P < .0001), on postoperative day 1 (P = .005) and postoperative day 2 (P = .037). Preoperatively, CFNC patients required 61% less morphine equivalent (P = .007). CFNC patients had a lower rate of opioid-related side effects compared with SA patients (7% vs 47%; P = .035). CONCLUSION:CFNC patients were discharged to home more frequently. Use of a CFNC decreased daily average patient-reported pain scores, preoperative opioid usage, and opioid-related side effects after THA for hip fracture. Based on these data, we recommend routine use of perioperative CFNC in hip fracture patients undergoing THA.

OBJECTIVE:To evaluate the effect of continuous femoral nerve catheter (CFNC) for postoperative pain control in geriatric proximal femur fractures compared with standard analgesia (SA) treatment. DESIGN/METHODS:Retrospective comparative study. SETTING/METHODS:Academic Level 1 trauma center. PATIENTS/PARTICIPANTS/METHODS:We retrospectively identified 265 consecutive geriatric hip fracture patients who underwent surgical treatment. INTERVENTION/METHODS:One hundred forty-nine patients were treated with standard analgesia without nerve catheter whereas 116 patients received an indwelling CFNC. MAIN OUTCOME MEASUREMENT/METHODS:Daily average preoperative and postoperative pain scores, daily morphine equivalent consumption, opioid-related side effects and discharge disposition. RESULTS:Patients with CFNC patients reported lower average pain scores preoperatively (1.9 ± 1.7 for CFNC vs. 4.7 ± 2 for SA; P < 0.0001), on postoperative day 1 (1.5 ± 1.6 for CFNC vs. 3 ± 1.7 for SA; P < 0.0001) and postoperative day 2 (1.2 ± 1.5 for CFNC vs. 2.6 ± 2.1 for SA; P < 0.0001). CFNC group consumed 39% less morphine equivalents on postoperative day 1 (4.4 ± 5.8 mg for CFNC vs. 7.2 ± 10.8 mg for SA; P = 0.005) and 50% less morphine equivalent on postoperative day 2 (3.4 ± 4.4 mg for CFNC vs. 6.8 ± 13 mg for SA; P = 0.105). Patients with CFNC had a lower rate of opioid-related side effects compared with patients with SA (27.5% for CFNC vs. 47% for SA; P = 0.001). More patients with CFNC were discharged to home with or without health services than patients with SA (15% for CFNC vs. 6% for SA; P = 0.023). CONCLUSION/CONCLUSIONS:Continuous femoral nerve catheter decreased daily average patient-reported pain scores, narcotic consumption while decreasing the rate of opioid-related side effects. Patients with CFNC were discharged to home more frequently. LEVEL OF EVIDENCE/METHODS:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:Addressing recurrent instability in patients with poor bone stock and inadequate abductor tensioning remains a challenge in revision total hip arthroplasty. One treatment method is implantation of a constrained liner. The purpose of this study was to determine clinical outcomes, redislocation rate, and revisions of a focally constrained liner in a high-risk patient cohort. METHODS:Fifty-eight hips between 2008 and 2011 underwent implantation of a focally constrained liner. Nineteen were placed concurrent with acetabular component revision and 39 were placed into a well-fixed acetabular shell. Mean age was 69 years and mean number of previous ipsilateral hip surgeries was 4.2. At mean follow-up of 3.5 years, we analyzed clinical outcomes, redislocation, and revisions. RESULTS:Mean Harris Hip Scores was 74. Fourteen hips (24%) were revised and 3 hips (5%) required reoperation at final follow-up. Eleven hips (19%) redislocated at a mean time to dislocation of 12.2 months; 31% (11 of 36 patients) that underwent modular exchange specifically for instability redislocated. Risk factors for redislocation included number of previous surgeries (P = .013), implantation of a 28 mm femoral head (hazards ratio 12.8), revision indication of instability (P = .04), and modular exchange with constrained liner implantation without acetabular shell revision (P = .01). CONCLUSION:Implantation of a focally constrained liner in revision total hip arthroplasty for recurrent instability has a high failure rate, especially with a modular exchange. Although concurrent acetabular revision had a lower redislocation rate, the decision to revise a well-fixed cup should be weighed with potential complications associated with cup revision.

AIMS/OBJECTIVE:Animal models have been developed that allow simulation of post-traumatic joint contracture. One such model involves contracture-forming surgery followed by surgical capsular release. This model allows testing of antifibrotic agents, such as rosiglitazone. METHODS:A total of 20 rabbits underwent contracture-forming surgery. Eight weeks later, the animals underwent a surgical capsular release. Ten animals received rosiglitazone (intramuscular initially, then orally). The animals were sacrificed following 16 weeks of free cage mobilisation. The joints were tested biomechanically, and the posterior capsule was assessed histologically and via genetic microarray analysis. RESULTS:There was no significant difference in post-traumatic contracture between the rosiglitazone and control groups (33° (standard deviation (sd) 11) vs 37° (sd14), respectively; p = 0.4). There was no difference in number or percentage of myofibroblasts. Importantly, there were ten genes and 17 pathways that were significantly modulated by rosiglitazone in the posterior capsule. DISCUSSION/CONCLUSIONS:Rosiglitazone significantly altered the genetic expression of the posterior capsular tissue in a rabbit model, with ten genes and 17 pathways demonstrating significant modulation. However, there was no significant effect on biomechanical or histological properties.Cite this article: M. P. Abdel. Effectiveness of rosiglitazone in reducing flexion contracture in a rabbit model of arthrofibrosis with surgical capsular release: A biomechanical, histological, and genetic analysis. Bone Joint Res 2016;5:11-17. doi: 10.1302/2046-3758.51.2000593.

BACKGROUND:Dupuytren's disease is an inherited disorder in which patients develop fibrotic contractures of the hand. Current treatment strategies include surgical excision or enzymatic digestion of fibrotic tissue. MicroRNAs, which are key posttranscriptional regulators of genes expression, have been shown to play an important regulatory role in disorders of fibrosis. Therefore in this investigation, we apply high throughput next generation RNA sequencing strategies to characterize microRNA expression in diseased and healthy palmar fascia to elucidate molecular mechanisms responsible for pathogenic fibrosis. METHODS:We applied high throughput RNA sequencing techniques to quantify the expression of all known human microRNAs in Dupuytren's and control palmar fascia. MicroRNAs that were differentially expressed between diseased and healthy tissue samples were used for computational target prediction using the bioinformatics tool ComiR. Molecular pathways that were predicted to be differentially expressed based on computational analysis were validated by performing RT-qPCR on RNA extracted from diseased and non-diseased palmar fascia biopsies. RESULTS:A comparison of microRNAs expressed in Dupuytren's fascia and control fascia identified 74 microRNAs with a 2-fold enrichment in Dupuytren's tissue, and 32 microRNAs with enrichment in control fascia. Computational target prediction for differentially expressed microRNAs indicated preferential targeting of collagens and extracellular matrix related proteins in control palmar fascia. RT-qPCR confirmed the decreased expression of microRNA targeted collagens in control palmar fascia tissues. DISCUSSION/CONCLUSIONS:Control palmar fascia show decreased expression of mRNAs encoding collagens that are preferentially targeted by microRNAs enriched in non-diseased fascia. Thus alterations in microRNA regulatory networks may play an important role in driving the pathogenic fibrosis seen in Dupuytren's disease via direct regulatory effects on extracellular matrix protein synthesis. CONCLUSION/CONCLUSIONS:Dupuytren's fascia and healthy palmar fascia can be distinguished by unique microRNA profiles, which are predicted to preferentially target collagens and other extracellular matrix proteins.

The results of total hip arthroplasty in 42 primary total hip arthroplasties in super-obese patients (BMI ≥ 50) were reviewed. The mean body mass index for the study group was 53.2 kg/m(2) (range 50-64). The mean preoperative Harris hip score improved from 35 to 74.8 postoperatively (P<0.001). Twenty-four of the THAs had at least one complication. At least one major complication occurred in 11 of the THAs and at least one minor complication in 14 THAs When compared to matched 2:1 control group the super-obese patient had a significantly increased risk to experience a complication (HR 5.6 , CI = 2.8-11.0). Caution should be used when proceeding with primary total hip arthroplasty with a BMI greater than 50.

BACKGROUND:We observed isolated tibial component debonding from the cement in one modern primary TKA design (NexGen LPS 3° tibial tray; Zimmer, Warsaw, IN, USA). This failure mechanism is sparsely reported in the literature. QUESTIONS/PURPOSES/OBJECTIVE:We (1) assessed survivorship of this tibial tray with special emphasis on debonding; (2) described clinical and radiographic features associated with tibial failure; and (3) compared patient and radiographic features of the failures with a matched cohort. METHODS:A total of 1337 primary TKAs were performed with a cemented NexGen LPS 3° tibial tray over an 11-year period. Twenty-five knees (1.9%) were revised for tibial debonding. BMI and radiographic alignment in the tibial debonding group were compared with a matched control group. Implant survivorship was assessed using tibial debonding as the end point. RESULTS:Survival free of revision from tibial debonding was 100% at 1 year and 97.8% at 5 years. The tibial failures shared a typical radiographic pattern with debonding at the cement-implant interface and subsidence into varus and flexion. We found no link between limb alignment or individual component alignment and failure because 22 of the 25 failures occurred in well-aligned knees. CONCLUSIONS:Our standardized followup of patients undergoing TKA at routine intervals allowed us to discover a higher rate of revision resulting from tibial debonding. We have discontinued the use of this particular tibial tray for primary TKA and surveillance for patients undergoing TKA continues to be warranted.