Highly Porous Acetabular Cup and Augment Constructs in Complex Revision Total Hip Arthroplasty: What Predicts 10-Year Implant Survivorship?

BACKGROUND: Porous tantalum acetabular cup and augment constructs have demonstrated favorable outcomes up to 5 years postsurgery despite severe bone loss during revision total hip arthroplasty (THA). Prior literature lacks long-term studies with substantial case numbers. This study aims to assess long-term clinical and radiographic outcomes 10 years postsurgery in patients undergoing revision THA with porous tantalum acetabular cup-augment constructs and determine factors associated with long-term survivorship. METHODS: Between 2000 and 2012, 157 revision THAs were performed in cases with major acetabular defects (mainly Paprosky type IIIA and IIIB) utilizing porous tantalum cup-augment constructs. Pelvic discontinuity was noted intraoperatively in 17 hips (11%). Postoperative radiographs were evaluated at regular intervals for implant stability and radiolucent lines. There were 49 patients who had complete radiographic follow-up at 10 years or longer postsurgery. RESULTS: The 10-year survivorship free of revision of the cup-augment construct for aseptic loosening was 93%, free of any acetabular construct revision was 91%, free of any hip rerevision was 77%, and free of any reoperation was 75%. Pelvic discontinuity was associated with increased risk of reoperation (hazard ratio [HR] = 2.8), any hip rerevision (HR = 3.2), any cup-augment construct revision (HR = 11.8), and aseptic construct revision (HR = 10.0). Of unrevised cases with radiographs at 10 years, 4 hips showed radiographic loosening. Mean Harris hip scores improved from 47 preoperatively to 79 at 10 years. CONCLUSIONS: Porous tantalum acetabular cup-augment constructs used in revision THA with severe acetabular bone loss provide excellent implant survivorship at 10 years when the acetabulum is intact. Due to lower survivorship of cup-augment constructs in cases of pelvic discontinuity, additional construct fixation or stabilization methods are recommended, when a discontinuity is present. LEVEL OF EVIDENCE: IV.

Comparative Survival of Contemporary Cementless Acetabular Components Following Revision Total Hip Arthroplasty.

BACKGROUND: The advent of highly porous ingrowth surfaces and highly crosslinked polyethylene has been expected to improve implant survivorship in revision total hip arthroplasty. Therefore, we sought to evaluate the survival of several contemporary acetabular designs following revision total hip arthroplasty. METHODS: Acetabular revisions performed from 2000 to 2019 were identified from our institutional total joint registry. We studied 3,348 revision hips, implanted with 1 of 7 cementless acetabular designs. These were paired with highly crosslinked polyethylene or dual-mobility liners. A historical series of 258 Harris-Galante-1 components, paired with conventional polyethylene, was used as reference. Survivorship analyses were performed. For the 2,976 hips with minimum 2-year follow-up, the median follow-up was 8 years (range, 2 to 35 years). RESULTS: Contemporary components with adequate follow-up had survivorship free of acetabular rerevision of ≥95% at 10-year follow-up. Relative to Harris-Galante-1 components, 10-year survivorship free of all-cause acetabular cup rerevision was significantly higher in Zimmer Trabecular Metarevision (hazard ratio (HR) 0.3, 95% confidence interval (CI) 0.2-0.45), Zimmer Trabecular MetaModular (HR 0.34, 95% CI 0.13-0.89), Zimmer Trilogy (HR 0.4, 95% CI 0.24-0.69), DePuy Pinnacle Porocoat (HR 0.24, 95% CI 0.11-0.51), and Stryker Tritanium revision (HR 0.46, 95% CI 0.24-0.91) shells. Among contemporary components, there were only 23 rerevisions for acetabular aseptic loosening and no rerevisions for polyethylene wear. CONCLUSION: Contemporary acetabular ingrowth and bearing surfaces were associated with no rerevisions for wear and aseptic loosening was uncommon, particularly with highly porous designs. Therefore, it appears that contemporary revision acetabular components have dramatically improved upon historical results at available follow-up.

Contemporary Outcomes of Transfemoral Amputation After Total Knee Arthroplasty.

BACKGROUND: Transfemoral amputation (TFA) is a salvage procedure for unreconstructable failed total knee arthroplasty (TKA). Prior studies have reported poor outcomes, patient survival, and prosthetic use. The purpose of this study was to analyze patient outcomes and prosthetic utilization in a contemporary group of patients undergoing TFA in the setting of a TKA. METHODS: We reviewed 112 patients undergoing TFA with a prior TKA. Indications for amputation and postoperative functional measures were captured through chart review. Patients were contacted by survey to assess the quality of life. The mean follow-up after TFA was 4 years. RESULTS: Amputations were performed for a chronically infected TKA (n = 87, 78%) and an ischemic limb without signs of an infected TKA (n = 22, 20%). The 10-year survival after TFA was 21%. Of the patients not lost to follow-up, 53 (47%) patients were fitted for a prosthesis. Patients who underwent a TFA after the year 2000 were more likely to be fit for a prosthesis (odds ratio 7.27, P < .01); however, patients were likely to be ambulatory before TFA than after TFA (odds ratio 3.68, P < .01). After TFA, the mean 12-Item Short Form Survey scores for the mental and physical components were 54 ± 13 and 34 ± 7, with no difference in scores between patients fitted for a prosthesis and those who were not (P > .05). CONCLUSION: Patients undergoing a TFA after TKA due to failure of the TKA are more likely to be fit for a prosthesis; however, they reported no better quality of life and satisfaction compared with patients not fit for a prosthesis. LEVELS OF EVIDENCE: Level III, Therapeutic.

Total Femur Antibiotic Spacers: Effective Salvage for Complex Periprosthetic Joint Infections.

BACKGROUND: A simultaneous periprosthetic joint infection (PJI) of an ipsilateral hip and knee arthroplasty is a challenging complication of lower extremity reconstructive surgery. We evaluated the use of total femur antibiotic-impregnated polymethylmethacrylate (PMMA) bone cement spacers in the staged treatment of such limb-threatening PJIs. METHODS: Thirteen patients were treated with a total femur antibiotic spacer. The mean age at the time of spacer placement was 65 years. Nine patients had polymicrobial PJIs. All spacers incorporated vancomycin (3.0 g/40 g PMMA) and gentamicin (3.6 g/40 g PMMA), while 8 also included amphotericin (150 mg/40 g PMMA). Eleven spacers were biarticular. Twelve spacers were implanted through one longitudinal incision, while 8 of 12 reimplantations occurred through 2 smaller, separate hip and knee incisions. Mean follow-up after reimplantation was 3 years. RESULTS: Twelve (92%) patients underwent reimplantation of a total femur prosthesis at a mean of 26 weeks. One patient died of medical complications 41 days after spacer placement. At latest follow-up, 3 patients had experienced PJI recurrence managed with irrigation and debridement. One required acetabular component revision for instability. All 12 reimplanted patients retained the total femur prosthesis with no amputations. Eleven (91%) were ambulatory, and 7 (58%) remained on suppressive antibiotics. CONCLUSION: Total femur antibiotic spacers are a viable, but technically demanding, limb-salvage option for complex PJIs involving the ipsilateral hip and knee. In the largest series to date, there were no amputations and 75% of reimplanted patients remained infection-free. Radical debridement, antimicrobial diversity, prolonged spacer retention, and limiting recurrent soft tissue violation are potential tenets of success. LEVEL OF EVIDENCE: IV.

Outcomes of Vancouver C Periprosthetic Femur Fractures.

BACKGROUND: Periprosthetic femur fractures (PFFs) that occur distal to a total hip arthroplasty, Vancouver C fractures, are challenging to treat. We aimed to report patient mortality, reoperations, and complications following Vancouver C PFFs in a contemporary cohort all treated with a laterally based locking plate. METHODS: We retrospectively identified 42 consecutive Vancouver C PFFs between 2004 and 2018. There was a high prevalence of comorbidities, including 9 patients with neurologic conditions, 9 with a history of cancer, 8 diabetics, and 8 using chronic anticoagulation. Mean time from total hip arthroplasty to PFF was 6 years (range 1 month to 25 years). All fractures were treated with a laterally based locking plate. Fixation bypassed the femoral component in 98% of cases and extended as proximal as the lesser trochanter in 18%. Kaplan-Meier survival was used for patient mortality, and a competing risk model was used to analyze survivorship free of reoperation and nonunion. Mean follow-up was 2 years. RESULTS: Patient mortality was 5% at 90 days and 31% at 2 years. Cumulative incidence of reoperation was 13% at 2 years. There were 5 reoperations including revision osteosynthesis for nonunion and/or hardware failure (2), debridement and hardware removal for infection (2), and removal of hardware and total knee arthroplasty for post-traumatic arthritis (1). Cumulative incidence of nonunion was 10% at 2 years. CONCLUSION: Patients who sustained a Vancouver C PFFs had a high mortality rate (31%) at 2 years. Moreover, 13% of patients required a reoperation within 2 years, most commonly for infection or nonunion.

Synchronous Periprosthetic Joint Infections: High Mortality, Reinfection, and Reoperation.

BACKGROUND: Synchronous periprosthetic joint infections (PJIs) are a catastrophic complication with potentially high mortality. We aimed to report mortality, risk of reinfection, revision, reoperation, and implant survivorship after synchronous PJIs. METHODS: We identified 34 patients treated for PJI in more than one joint within a single 90-day period from 1990 to 2018. PJIs involved bilateral knee arthroplasty (27), bilateral hip arthroplasty (4), 1 knee arthroplasty and 1 elbow arthroplasty (1), 1 knee arthroplasty and 1 shoulder arthroplasty (1), and bilateral hip and knee arthroplasty (1). Irrigation and debridement with component retention was performed in 23 patients, implant resection in 10 patients, and a combination of irrigation and debridement with component retention and implant resection in 1 patient. A competing risk model was used to analyze implant survivorship, and Kaplan-Meier survival was used for patient mortality. Mean follow-up was 6 years. RESULTS: Mortality was high at 18% at 30 days and 27% at 1 year. The 1-year cumulative incidence of any reinfection was 13% and 27% at 5 years. The 1-year cumulative incidence of any revision or implant removal was 6% and 20% at 5 years. The 1-year cumulative incidence of unplanned reoperation was 25% and 35% at 5 years. Rheumatoid arthritis was associated with increased risk of mortality (HR 7, P < .01), as was liver disease (HR 4, P = .02). CONCLUSION: In the largest series to date, patients with synchronous PJIs had a high 30-day mortality rate of 18%, and one-fourth underwent unplanned reoperation within the first year.

Low-Dose vs Regular-Dose Aspirin for Venous Thromboembolism Prophylaxis in Primary Total Joint Arthroplasty.

BACKGROUND: Consensus on whether low-dose (81 mg) or regular-dose (325 mg) aspirin (ASA) is more effective for venous thromboembolism (VTE) chemoprophylaxis in primary total joint arthroplasties (TJAs) is not reached. The goal of this study is to evaluate the efficacy of low-dose and regular-dose ASA for VTE chemoprophylaxis in primary total hip arthroplasties and total knee arthroplasties. METHODS: We retrospectively identified 3512 primary TJAs (2344 total hip arthroplasties and 1168 total knee arthroplasties) with ASA used as VTE chemoprophylaxis between 2000 and 2019. Patients received ASA twice daily for 4-6 weeks after surgery with 961 (27%) receiving low-dose ASA and 2551 (73%) receiving regular-dose ASA. The primary endpoint was 90-day incidence of symptomatic VTEs. Secondary outcomes were gastrointestinal (GI) bleeding events and mortality. The mean age at index TJA was 66 years, 54% were female, and mean body mass index was 31 kg/m2. The mean Charlson Comorbidity Index was 3.5. Mean follow-up was 3 years. RESULTS: There was no difference in 90-day incidence of symptomatic VTEs between low-dose and regular-dose ASA (0% vs 0.1%, respectively; P = .79). There were no GI bleeding events in either group. There was no difference in 90-day mortality between low-dose and regular-dose ASA (0.3% vs 0.1%, respectively; P = .24). CONCLUSION: In 3512 primary TJA patients treated with ASA, we found a cumulative incidence of VTE <1% at 90 days. Although this study is underpowered, it appears that twice daily low-dose ASA was equally effective to twice daily regular-dose ASA for VTE chemoprophylaxis, with no difference in risk of GI bleeds or mortality. LEVEL OF EVIDENCE: III, retrospective cohort study.

Total Hip Arthroplasty in Patients With Osteopetrosis.

BACKGROUND: Osteopetrosis is an inherited bone disease associated with high risk of osteoarthritis and fracture non-union, which can lead to total hip arthroplasty (THA). Bone quality and morphology are altered in these patients, and there are limited data on results of THA in these patients. The goals of this study were to describe implant survivorship, clinical outcomes, radiographic results, and complications in patients with osteopetrosis undergoing primary THA. METHODS: We identified 7 patients (9 hips) with osteopetrosis who underwent primary THA between 1970 and 2017 utilizing our total joint registry. The mean age at index THA was 48 years and included two males and five females. The mean follow-up was 8 years. RESULTS: The 10-year survivorship free from any revision or implant removal was 89%, with 1 revision and 1 resection arthroplasty secondary to periprosthetic femoral fractures. The 10-year survivorship free from any reoperation was 42%, with 4 additional reoperations (2 ORIFs for periprosthetic femoral fractures, 1 sciatic nerve palsy lysis of adhesions, 1 hematoma evacuation). Harris hip scores significantly increased at 5 years (P = .04). Five hips had an intraoperative acetabular fracture, and 1 had an intraoperative femur fracture. All postoperative femoral fractures occurred in patients with intramedullary diameter less than 5 mm at a level 10 cm distal to the lesser trochanter. CONCLUSION: Primary THA in patients with osteopetrosis is associated with good 10-year implant survivorship (89%), but a very high reoperation (58%) and periprosthetic femoral fracture rate (44%). Femoral fractures appear associated with smaller intramedullary diameters.

Orthopedic Surgery and Anesthesiology Surgical Improvement Strategies Project-Phase II Outcomes.

BACKGROUND: Our institution previously initiated a perioperative surgical home initiative to improve quality and efficiency across the hospital arc of care of primary total knee arthroplasty and total hip arthroplasty patients. Phase II of this project aimed to (1) expand the perioperative surgical home to include revision total hip arthroplasties and total knee arthroplasties, hip preservation procedures, and reconstructions after oncologic resections; (2) expand the project to include the preoperative phase; and (3) further refine the perioperative surgical home goals accomplished in phase I. METHODS: Phase II of the Orthopedic Surgery and Anesthesiology Surgical Improvement Strategies project ran from July 2018 to July 2019. The evaluated arc of care spanned from the preoperative surgical consult visit through 90 days postoperative in the expanded population described above. RESULTS: Mean length of stay decreased from 2.2 days to 2.0 days (P < .001), 90-day readmission decreased from 3.0% to 1.6% (P < .001), and Press-Ganey scores increased from 77.1 to 79.2 (97th percentile). Mean and maximum pain scores and opioid consumption remained unchanged (lowest P = .31). Annual surgical volume increased by 10%. Composite changes in surgical volume and cost reductions equaled $5 million. CONCLUSION: Application of previously successful health systems engineering tools and methods in phase I of Orthopedic Surgery and Anesthesiology Surgical Improvement Strategies enabled additional evolution of an orthopedic perioperative surgical home to encompass more diverse and complex patient populations while increasing system-wide quality, safety, and financial outcomes. Improved process and outcomes metrics reflected increased efficiency across the episode of care without untoward effects. LEVEL OF EVIDENCE: III Therapeutic.

Orthopedic Surgery and Anesthesiology Surgical Improvement Strategies Project: Phase I Outcomes.

BACKGROUND: This study aimed to improve institutional value-based patient care processes, provider collaboration, and continuous process improvement mechanisms for primary total hip arthroplasties and total knee arthroplasties through establishment of a perioperative orthopedic surgical home. METHODS: On June 1, 2017, an institutionally sponsored initiative commenced known as the orthopedic surgery and anesthesiology surgical improvement strategy project. A multidisciplinary team consisting of orthopedic surgeons, anesthesiologists, advanced practice providers, nurses, pharmacists, physical therapists, social workers, and hospital administration met regularly to identify areas for improvement in the preoperative, intraoperative, and post-anesthesia care unit, and postoperative phases of care. RESULTS: Mean hospital length of stay decreased from 2.7 to 2.2 days (P < .001), incidence of discharge to a skilled nursing facility decreased from 24% to 17% (P = .008), and the number of patients receiving physical therapy on the day of surgery increased from 10% to 100% (P < .001). Press-Ganey scores increased from 74.9 to 75.8 (94th percentile), while mean and maximum pain scores, opioid consumption, and hospital readmission rates remained unchanged (lowest P = .29). Annual total hip arthroplasty and total knee arthroplasty surgical volume increased by 11.4%. Decreased hospital length of stay and increased surgical volume yielded a combined annual savings of $2.5 million across the 9 involved orthopedic surgeons. CONCLUSION: Through application of perioperative surgical home tools and concepts, key advances included phase of care integration, enhanced data management, decreased length of stay, coordinated perioperative management, increased surgical volume without personnel additions, and more efficient communication and patient care flow across preoperative, intraoperative, and postoperative phases. LEVEL OF EVIDENCE: III Therapeutic.

Contemporary Total Hip and Total Knee Arthroplasty Results in Patients with Hemochromatosis.

BACKGROUND: Hemochromatosis can result in metabolic bone pathology (due to excessive iron absorption) and degenerative joint disease, leading to total joint arthroplasties. The aim of this study is to analyze the survivorship, complications, radiographic results, and clinical outcomes of patients with hemochromatosis who received either a total hip arthroplasty (THA) or a total knee arthroplasty (TKA). METHODS: We identified 34 lower extremity arthroplasties in 29 patients with hemochromatosis performed between 2000 and 2016. There were 17 primary THAs in 15 patients and 17 primary TKAs in 14 patients. Mean age at arthroplasty was 63 years with 76% being male. The mean body mass index was 28 kg/m2. Mean follow-up was 5 years. RESULTS: The survivorship free from any revision for THAs was 94% at 10 years. One patient was revised for aseptic loosening of the femoral stem at 6 months. In THA patients, no infections, no other complications, and no radiographic evidence of aseptic loosening were identified. Harris Hip Scores improved from a mean of 55 preoperatively to 94 postoperatively (P < .001). The survivorship free from any revision for TKAs was 100% at 10 years. Two patients (12%) developed acquired idiopathic stiffness postoperatively; no infections were identified. There was no radiographic evidence of aseptic loosening in any TKA. Knee Society Scores improved from a mean of 61 preoperatively to 94 postoperatively (P < .001). CONCLUSION: This study found excellent survivorship, significant improvements in clinical outcomes, and a very low complication profile for both THA and TKA in patients with hemochromatosis.

Outcomes of knee arthroplasty for primary treatment of pathologic peri-articular fractures of the distal femur and proximal tibia.

BACKGROUND: Treatment goals for pathologic fractures about the knee include pain relief and unrestricted weight bearing. In cases of condylar destruction, these fractures may not be amenable to internal fixation, and arthroplasty may be considered. The purpose of this study was to analyze the outcomes of knee arthroplasty for primary treatment of impending or pathologic fractures of the distal femur or proximal tibia. METHODS: Fifteen (8 males and 7 females) patients, mean age 62 ± nine years, undergoing arthroplasty for management of a pathologic peri-articular distal femur (n = 11) or proximal tibia (n = 4) fracture between 2001 and 2017 were reviewed. Implants included tumour endoprostheses (n = 11) and rotating hinged total knees (n = 4). Pathology included metastatic disease (n = 14) and lymphoma (n = 1). Eight (53%) patients presented with a fracture while the remainder had large impending lesions. RESULTS: Mean follow-up was 19 months. At final follow-up, 11 patients had died with overall five year survival of 33%. Two (13%) patients required re-operation; including wound irrigation and debridement (n = 1) and above knee amputation for local recurrence (n = 1). An additional two (13%) patients developed post-operative VTE. MSTS, KSS, and KSS-F scores improved from a mean 12 ± 16%, 30 ± 11, and 14 ± 24 pre-operatively to 69 ± 26%, 75 ± 16, and 67 ± 25 at final follow-up, respectively (P < 0.001). Thirteen (87%) patients had severe pain prior to surgery with no patients (0%, P < 0.001) reporting severe pain at last follow-up. CONCLUSION: Knee arthroplasty provided improved function and full weight-bearing making it an effective treatment for pathologic periarticular fractures of the distal femur and proximal tibia.

Outcomes of Endoprosthetic Replacement for Salvage of Failed Fixation of Malignant Pathologic Proximal Femur Fractures.

BACKGROUND: Internal fixation is often used to treat pathologic proximal femur fractures. However, nonunion and/or tumor progression may lead to hardware failure. In such cases, endoprosthetic replacement may be considered. The purpose of this study is to analyze the outcome of patients undergoing conversion to an endoprosthetic replacement following failed fixation of a pathological proximal femur fracture. METHODS: We identified 26 patients who underwent conversion hip arthroplasty for salvage of failed fixation of a pathologic proximal femur fracture between 2000 and 2016. Previous surgical hardware included femoral nail (n = 18), dynamic hip screw (n = 5), proximal femoral locking plate (n = 1), blade plate (n = 1), and cannulated screws (n = 1). Twenty-one patients had metastatic disease, 4 myeloma, and 1 lymphoma. All received adjuvant or neoadjuvant radiotherapy at a mean dose of 30 Gy. RESULTS: There were 15 males and 11 females with mean age 63 ± 11 years. Patients underwent conversion arthroplasty at a mean of 13 ± 12 months after initial fixation. At final follow-up, 19 patients had died, with 5-year overall survival of 35%. Conversion to arthroplasty was performed due to disease progression (n = 12), hardware failure (n = 8), and nonunion (n = 6). Eight hips required reoperation, most commonly for infection (n = 4). At last follow-up, the Harris Hip Scores (P < .001) and Musculoskeletal Tumor Society Scores (P < .001) significantly improved from a mean of 24 and 14 preoperatively to 68 and 59 postoperatively, respectively. CONCLUSION: Conversion hip arthroplasty reliably provides improved quality of life and immediate weight bearing, making it an effective treatment for salvage of failed fixation of pathologic proximal femur fractures.

Thirty-Day Major and Minor Complications Following Total Hip Arthroplasty-A Comparison of the Direct Anterior, Lateral, and Posterior Approaches.

BACKGROUND: The choice of surgical approach during total hip arthroplasty (THA) remains highly controversial. The aim of the present study was to compare 30-day major and minor complications, following primary THA between the direct anterior, lateral, and posterior approaches. METHODS: Our hospital performs primary THAs using all 3 aforementioned approaches based on surgeon preference. Patients who underwent primary THA from August 2010 to August 2017 were identified using our institution's total joint registry, and their data were combined with prospectively collected data from the National Surgical Quality Improvement Program database (which evaluates a random sample of approximately 20% of all surgical patients in our hospital). Baseline characteristics, operative variables, and postoperative complications were then compared between the three groups. RESULTS: The analysis comprised 1967 primary THAs (1913 patients), whereby 56%, 29%, and 15% were performed through a posterior, lateral, and direct anterior approach, respectively. Thirty-day major and minor complications occurred in 3.9% and 9.4% of surgeries, respectively. After adjusting for baseline patient characteristics, there was no significant difference in major or minor perioperative complications between the 3 approaches. CONCLUSIONS: This study compared perioperative complications between the 3 most commonly used approaches for THA utilizing a synthesis of our institutional total joint registry and high-quality National Surgical Quality Improvement Program data. Thirty-day major and minor complications were similar regardless of the surgical approach employed, which may help surgeons and patients simplify the multiple considerations taken into account when deciding on surgical approach for primary THA. LEVEL OF EVIDENCE: Therapeutic, Level III.

Mild Coronal Stem Malalignment Does Not Negatively Impact Survivorship or Clinical Results in Uncemented Primary Total Hip Arthroplasties With Dual-Tapered Implants.

BACKGROUND: Proper component positioning in total hip arthroplasty (THA) is crucial for implant fixation and hip stability. The purpose of this study is to assess if neutral coronal stem alignment (0° ± 3°) improved long-term survivorship in uncemented femoral components. METHODS: Between 2005 and 2010, 1028 primary THAs were performed with 2 contemporary dual-tapered, proximally coated uncemented stem types. Alignment was measured immediately postoperatively and at most recent follow-up. In total, 978 femoral stems (95%) were within 0° ± 3° of the neutral anatomic coronal axis, and the 50 stems (5%) outside that range were considered outliers (3.1° of valgus to 4.8° of varus). Outcomes analyzed included implant survivorship, Harris Hip Scores, and incidence of dislocation. Mean follow-up was 5 years. RESULTS: Survivorship free of aseptic femoral component loosening was 99.3% and 98.2% at 5 and 8 years in the neutral group vs 100% at 5 and 8 years in the outlier group (P = .98). Survivorship free of femoral component revision for any reason was 99.1% and 97.3% at 5 and 8 years vs 100% at 5 and 8 years, respectively (P = .80). Harris Hip Scores were similar (89 in both groups; P = .84) at most recent follow-up. The incidence of mild to moderate thigh pain was also similar in both groups (6.1% vs 6%, P = .85). The incidence of dislocation was 1.5% at 8 years, and similar between both groups (P = .77). CONCLUSION: Slight malalignment of contemporary dual-tapered uncemented THA femoral components does not appear to negatively impact survivorship or clinical outcomes, which is in contrast to cemented femoral components. LEVEL OF EVIDENCE III: Case-control study.

Contact Kinematics Correlates to Tibial Component Migration Following Single Radius Posterior Stabilized Knee Replacement.

BACKGROUND: Contact kinematics between total knee arthroplasty components is thought to affect implant migration; however, the interaction between kinematics and tibial component migration has not been thoroughly examined in a modern implant system. METHODS: A total of 24 knees from 23 patients undergoing total knee arthroplasty with a single radius, posterior stabilized implant were examined. Patients underwent radiostereometric analysis at 2 and 6 weeks, 3 and 6 months, and 1 and 2 years to measure migration of the tibial component in all planes. At 1 year, patients also had standing radiostereometric analysis examinations acquired in 0°, 20°, 40°, and 60° of flexion, and the location of contact and magnitude of any condylar liftoff was measured for each flexion angle. Regression analysis was performed between kinematic variables and migration at 1 year. RESULTS: The average magnitude of maximum total point motion across all patients was 0.671 ± 0.270 mm at 1 year and 0.608 ± 0.359 mm at 2 years (P = .327). Four implants demonstrated continuous migration of >0.2 mm between the first and second year of implantation. There were correlations between the location of contact and tibial component anterior-posterior tilt, varus-valgus tilt, and anterior-posterior translation. The patients with continuous migration demonstrated atypical kinematics and condylar liftoff in some instances. CONCLUSION: Kinematics can influence tibial component migration, likely through alterations of force transmission. Abnormal kinematics may play a role in long-term implant loosening.

Total Hip Arthroplasty After In Situ Fixation of Minimally Displaced Femoral Neck Fractures in Elderly Patients.

BACKGROUND: In situ screw fixation remains the most common treatment for minimally displaced femoral neck fractures (FNFs). Total hip arthroplasty (THA) can be used as a salvage procedure, but the results of conversion THA in this population have not been evaluated. The goals of this study were to evaluate (1) unique complications associated with conversion THA, (2) implant survivorship free of revision and reoperation, (3) radiographic results, and (4) clinical outcomes in patients undergoing conversion THA after in situ fixation of nondisplaced FNFs. METHODS: Between 2000 and 2014, 62 consecutive patients >65 years of age who underwent THA after in situ fixation of minimally displaced FNFs were identified. Indications were osteonecrosis (44%), post-traumatic/degenerative arthritis (35%), and nonunion (21%). Mean age was 78 years, and 73% patients were women. Mean follow-up was 5.5 years. RESULTS: One patient was revised for aseptic femoral loosening at 11 years. One patient underwent debridement and modular component exchange at 10 years for acute hematogenous periprosthetic joint infection. Two patients underwent acute reoperation without component exchange (one superficial wound infection, one hematoma evacuation). Survivorship free of reoperation for any indication was 97% at 5 years. No patients with surviving implants had radiographic evidence of loosening at 5 years. Harris hip scores improved from 35-85 (P < .01) after THA. CONCLUSION: Conversion THA was associated with clinical improvement, a low rate of complications, and excellent implant durability. Risks of loosening, dislocation, and periprosthetic fracture can be minimized with appropriate operative strategies and perioperative management.

Two-Stage Revision Total Hip Arthroplasty With a Specific Articulating Antibiotic Spacer Design: Reliable Periprosthetic Joint Infection Eradication and Functional Improvement.

BACKGROUND: Two-stage revision utilizing spacers loaded with high-dose antibiotic cement prior to reimplantation remains the gold standard for treatment of periprosthetic joint infections (PJI) in total hip arthroplasty (THA) in North America, but there is a paucity of data on mid-term outcomes. We sought to analyze the survivorship free of infection, clinical outcomes, and complications of a specific articulating spacer utilized during 2-stage revision. METHODS: One hundred thirty-five hips (131 patients) undergoing a 2-stage revision THA for PJI with a specific articulating antibiotic spacer design from 2005 to 2013 were retrospectively reviewed. Infections were classified according to the Musculoskeletal Infection Society criteria. Mean age at resection was 65 years and mean follow-up was 5 years (rang, 2-10). RESULTS: Survivorship free of any infection after reimplantation was 92% and 88% at 2 and 5 years, respectively. Patients with a host-extremity grade of C3 compared to all patients with a host grade of A [hazard ratio (HR) 4.1, P = .05] were significant risk factors for poorer infection-free survivorship after reimplantation. Harris hip scores improved from a mean of 58 to a mean of 71 in the spacer phase (P = .002) and a mean of 81 post-reimplantation (P = .001). Fourteen (10%) patients dislocated after reimplantation, 9 (7%) of which required re-revision. Trochanteric deficiency (HR 19, P < .0001), dislocation of the articulating spacer prior to reimplantation [which occurred in 7 (5%) patients, 5 of whom subsequently dislocated the definitive implant] (HR 16, P < .0001), and female gender (HR 5, P = .002) were significant risk factors for post-reimplantation dislocation. CONCLUSION: Insertion of an articulating antibiotic spacer during a 2-stage revision THA for PJI demonstrates reliable infection eradication and improvement in clinical function, including the spacer phase. Patients with trochanteric deficiency and an articulating spacer dislocation are at high risk of post-reimplantation dislocation; judicial use of a dual-mobility or constrained device should be considered in these patients.

High Rate of Positive Cultures in Patients Referred With Antibiotic Spacers as Part of 2-Stage Exchange.

BACKGROUND: Two-stage exchange for periprosthetic joint infection (PJI) in total knee arthroplasty (TKA) remains the gold standard treatment in North America. Occasionally, patients with knee PJI are referred for definitive management after resection and antibiotic spacer placement. Currently, little literature exists to suggest how these patients should be managed. The purpose of this study is to report the clinical outcomes of these patients. METHODS: We retrospectively identified 54 patients (54 knees) from 2000 to 2012 treated for PJI with initial TKA resection and spacer placement performed somewhere other than the definitive treatment center. The mean age at reimplantation was 64 years, with 59% being male. Redebridement and antibiotic spacer exchange was performed for all patients. Mean follow-up was 6.5 years. RESULTS: Of the 54 knees, 22 (41%) grew an organism from a culture taken at the time of redebridement and spacer exchange. The most common organism identified at redebridement was Staphylococcus aureus (41%). Obtaining positive cultures at redebridement was not associated with presenting erythrocyte sedimentation rate (P = .46), C-reactive protein (P = .57), or the presence of retained cement (P = .13). Forty-nine of 54 (91%) knees were ultimately reimplanted. Two-year survivorship free of infection in reimplanted knees was 98%. CONCLUSION: Patients referred with an antibiotic knee spacer for PJI have a high rate of positive cultures at the time of redebridement. Neither the presenting serology nor the identification of retained cement was associated with obtaining positive cultures at the time of redebridement. Nevertheless, this unique cohort of patients has favorable outcomes when redebrided with spacer exchange prior to reimplantation.

Contact Kinematic Differences Between Gap Balanced vs Measured Resection Techniques for Single Radius Posterior-Stabilized Total Knee Arthroplasty.

BACKGROUND: Measured resection (MR) and gap balancing (GB) are common surgical techniques for total knee arthroplasty (TKA). Controversy has arisen as each conceptually differs in how the knee is balanced through bone and soft tissue management. The objective of the present study was to compare both the frequency of condylar liftoff and the location of femorotibial contact from extension through midflexion between patients undergoing GB or MR TKA. METHODS: A total of 24 knees (23 patients) were randomly assigned at referral to either a surgeon performing MR or GB TKA with the same single radius, posterior-stabilized implant (12 per cohort). At 1-year postoperation, patients underwent biplanar radiographic imaging at 0°, 20°, 40°, and 60° of flexion. Condylar liftoff, contact location, and magnitude of excursion on each condyle were measured. Preoperative and postoperative clinical outcome scores were also collected. RESULTS: There was no difference (P = .41) in the frequency of liftoff between cohorts. The MR cohort had more posterior contact on the medial condyle (P < .01) and more anterior contact on the lateral condyle (P < .01) throughout flexion. Motion patterns were similar between cohorts, with similar medial (P = .48) and lateral (P = .44) excursion, which was equal in magnitude between condyles for both MR (P = .48) and GB (P = .73). There was no difference in clinical outcome scores between groups. CONCLUSION: For this particular implant system, GB and MR appear to produce similar kinematic and patient-reported outcome results.