Comparison of Anterior-Posterior Axis Versus Transepicondylar Axis in Patients Undergoing Simultaneous Bilateral Total Knee Arthroplasty: One Technique per Knee.

BACKGROUND: In primary total knee arthroplasty (TKA), the preferred reference line for setting femoral component rotation is debatable. This study compared the anterior-posterior axis line (APAL) versus the transepicondylar axis line (TEAL) in patients undergoing simultaneous bilateral TKA using a measured resection technique where one reference line was randomized to each knee. METHODS: This prospective study compared the two reference lines using posterior knee referencing with a cemented posterior stabilized knee. The study included 32 patients with osteoarthritis with both knees having similar varus knee deformities. All patients had the same surgical procedure with the only change being the selected femoral rotation axis line. Patients were followed up for a minimum of two years. RESULTS: There was no significant difference in any of the measured radiographic, operative, and clinical parameters, except for a postoperative radiographic limb alignment (APAL 179.7° vs TEAL 180.1° P = .04). The mean femoral external rotation relative to the posterior condylar axis line (PCAL) was 3.0 degrees (0-7 degrees) using the APAL and 3.3 degrees (2-7 degrees) using the TEAL (P = .46). Two-year knee flexion and revised Oxford Knee Scores showed no difference. Seventy-five percent of patients stated no preference for either knee technique. CONCLUSION: When using a measured resection, a posterior referencing technique, we found no difference in knee function and scores when setting femoral component rotation using the APAL versus TEAL. LEVEL OF EVIDENCE: 2, Randomized prospective study.

Comparison of Gap Balancing vs Measured Resection Technique in Patients Undergoing Simultaneous Bilateral Total Knee Arthroplasty: One Technique per Knee.

BACKGROUND: Total knee arthroplasty requires careful surgical technique to attain the goal of a well-aligned and symmetrically balanced knee. Soft tissue balance and correct femoral component rotation are paramount in achieving these goals. The two competing techniques to select femoral component rotation and soft tissue balance are the gap balance technique and the measured resection technique. METHODS: We performed a randomized, prospective study to compare the two techniques in patients undergoing simultaneous bilateral total knee arthroplasty, whereby one technique was performed in each knee. Fifty (50) subjects were enrolled into the study. The inclusion criteria were osteoarthritic varus knee deformities with similar deformities in both knees. Subjects were followed up for a minimum of two years. RESULTS: The knees balanced via the gap balance technique had significantly more posterior medial bone removed from the femur than those knees balanced via the measured resection technique (P < .001). Knees in the gap balance group tended to require more medial knee releases in extension and tended to have smaller sized femoral components as a result of cutting more bone from the femur in flexion. The modular tibial polyethylene bearing tended to be thicker in the gap balance group. Despite these differences, average knee flexion and functional revised Oxford Knee Scores at 2-year follow-up were not statistically different. CONCLUSION: At 2-year follow-up, there were no differences between the function and scores using the two techniques. Long-term follow-up will be necessary to evaluate any differences in long-term durability.

Functional Outcomes of a New Mobile-Bearing Ultra-Congruent TKA System: Comparison With the Posterior Stabilized System.

We determined whether a new mobile-bearing ultra-congruent (UC) TKA system provides better functional outcomes than an established posterior-stabilized (PS) prosthesis. The functional outcomes (motion arc, AKS scores, WOMAC Index, and SForm-36 scores evaluated at 1 and 2 years postoperatively), satisfaction and incidences of adverse events were compared between the knees implanted with mobile-bearing UC prosthesis (n=103) and the mobile-bearing PS prosthesis (n=99). At 2 years, mobile-bearing UC TKAs showed similar functional outcomes and satisfaction, but smaller motion arc compared to mobile-bearing PS TKAs (126° vs. 131°). There were no differences in the incidence of adverse events. Mobile-bearing UC prosthesis can be considered a safe and viable alternative to the PS design, with an expectation of smaller postoperative maximum flexion.

Prevalence and predictors of post-operative coronal alignment outliers and their association with the functional outcomes in navigated total knee arthroplasty.

We aimed to determine the prevalence and predictors for being an outlier after navigated TKA and asked whether navigated TKAs with perfect coronal alignment have better functional outcomes than those without it. Alignment was measured in 124 patients (191 knees) with navigated TKAs who were available for 1year functional outcome assessment. The outcomes were compared among the 3 subgroups divided by the deviation of mechanical axis from neutral (0°): the perfect, 0° or within 1°; the acceptable, 1°-3°; and the outlier, beyond 3°. The prevalence of outliers was 20.4%, and the severity of preoperative varus deformity was the strongest predictor. Accuracy of coronal alignment in radiographs did not correlate consistently with functional outcomes.

A 10-point preoperative checklist: selecting patients for outpatient joint replacement surgery.

BACKGROUND: With advancements in perioperative care, joint replacement (JR) surgery is undergoing a transition from opacified in-patient institutions to nimble out-patient Ambulatory Surgical Centers (ASC). The goal of JR in ASC setting is safe patient discharge with subsequent rehabilitation without readmission. Multi-modal preoperative rehabilitation (MMPR) is a novel field of perioperative care, encompassing comprehensive parameters to ensure smooth transition from fitness for surgery to JR in outpatient setting. At present, there are no open-access schemes for selecting patients qualified for JR in the ASC setting. In this article, we propose an evidence-based, 10-point systematic evaluation of patients with target endpoints for MMPR to qualify patients for JR as an outpatient procedure. This checklist is a non-proprietary scheme serving as an initial framework for surgeons exploring surgery in the ASC setting. BODY: We introduce factors for a prehabilitation scheme, called Checklist Outpatient-Joint Replacement (CO-JR) to qualify patients for outpatient JR surgery. These factors have been developed based on an extensive literature review and the significant experience of authors to incorporate variables that drive a successful outpatient JR procedure. The factors include patient education, psychiatric & cognitive ability, medical fitness, musculoskeletal capability, financial ability, transportation access, patient motivation, information technology (IT) capabilities, along with ability to recover independently at home postoperatively. The CO-JR scheme is under the process of validation at multiple institutions. We introduce this as a starting point for collaborative development of an open-access scheme for all surgeons to learn and adapt as needed for their respective global region. CONCLUSION: We established a non-proprietary 10-point CO-JR scheme, serving as a framework for surgeons to successfully select patients for JR surgery in the ASC setting. We encourage concomitant validation of this scheme globally. Our goal is to reach an international consensus on an open-access scheme, available for all surgeons to enrol patients for JR in the ASC setting, but modifiable to accommodate regional needs.

Implant-associated Mycobacterium tuberculosis infection (IMTI) in long-term, well-fixed implants.

Background: Orthopedic device infections caused by Mycobacterium tuberculosis, including Periprosthetic joint infection (PJI), are rare and peculiar due to its poor adherence to implant surface and weak ability of biofilm formation. We present successful treatment of 2 cases of implant associated Mycobacterium tuberculosis infection (IMTI) by meticulous surgical debridement and long-term anti-tubercular chemotherapy with retention of implant. Case descriptions: Case 1 : A case of Culture-Negative PJI, 4 years after left total hip replacement (THR) caused by M. tuberculosis. The patient presented with acute onset (<7 days) low grade fever and development of discharging sinus from the site of left surgical scar mark. Case 2: A patient with Kuntscher nailing done for open fracture right femur 22 years ago presented to clinic with complaints of discharging sinus (<7 days) from the surgical scar mark on right side. Both patients had negative cultures on presentation and underwent meticulous debridement with implant retention. Intra-operative samples were positive for M. tuberculosis on CB-NAAT and histopathology. They underwent successful treatment with 18 months of Anti Tubercular Treatment (ATT) without any relapse at 2 year-follow-up. Conclusion: Atypical, late onset discharging sinus with negative cultures should raise suspicion of IMTI. Intra-operative deep tissue samples should be analyzed for CB-NAAT for M. tuberculosis and histopathological analysis in all these cases. Meticulous debridement with 18 months chemotherapy poses viable option for successful treatment of IMTI, allowing retention of prosthesis.

Rare Case of Bizarre Parosteal Osteochondromatous Proliferation of Foot.

Introduction: Nora's lesion or bizarre parosteal osteochondromatous proliferation (BPOP) is a rare, benign lesion of small bones of hands and feet in adults. It composed of differing amounts of cartilage, bone, and spindle cells and an unusual form of calcified cartilage so-called "blue bone". Case Report: A 23-year-old male presented with swelling at the lateral side of the fifth toe of his right foot, which was separated from the adjacent toe. Radiographs showed a mass arising from the proximal phalanx of the little toe, with no medullary and cortical continuity. Excisional biopsy of the mass was performed, and a histologic diagnosis of BPOP of bone (Nora's lesion) was made. Conclusion: This case presented with a cartilaginous cap around tumor which is suggestive for benign nature of this tumor with some histological variation from bizarre variant along with no recurrence which is unlikely seen in BPOP.

Next generation sequencing identifies an increased diversity of microbes in post lavage specimens in infected TKA using a biofilm disrupting irrigant.

BACKGROUND: Periprosthetic joint infection (PJI) is a devastating complication of joint arthroplasty. In chronic PJI, a biofilm envelops the surface of implants, which contains microbiota within an extra-microbial polymeric matrix (EMPM). Microbial identification is paramount for effective treatment. In this study, we use a multi-modal, EMPM disrupting, neoadjuvant irrigant and compare the microbiota detected pre-lavage to post-lavage by two techniques: culture and Next Generation Sequencing (NGS). We suspect more organisms to be identified after applying an EMPM disrupting irrigant. METHODS: A multicenter, prospective study was conducted on 38 patients with known Total Knee Arthroplasty PJI. At initial arthrotomy, synovial fluid was obtained and analyzed for quantitative cultures and microbial NGS. Joint was then irrigated with Bactisure Lavage followed by Normal Saline. Post-lavage samples were similarly obtained and analyzed. RESULTS: In pre-lavage samples for cultures, 55.3% of samples were positive, identifying 11 unique organisms. In post-lavage samples for cultures, 13.2% of samples were positive, identifying 5 unique organisms. In pre-lavage samples for NGS, 79% were DNA signal positive, identifying 126 unique organisms. In post-lavage samples for NGS, 74% of samples were DNA signal positive, identifying 177 unique organisms. Moreover, 135/177 of these organisms were not identified pre-lavage. CONCLUSION: In this pre-to-post irrigant study, culture showed a decrease in the number of identifiable organisms post-lavage. In contrast NGS revealed an increase in the number of identifiable organisms post-lavage. Furthermore, NGS identified 135 additional organisms, not detected pre-lavage. This suggests an increased diversity of microbes may exist within EMPM, which are not cultivable.

Point-of-Care Coating of Revision Femoral Stems With Antibiotic-Loaded Calcium Sulfate: Reduction in Infection After 2nd Stage Reimplantation but Not With Aseptic Revisions.

Background: Infection rates in revision total hip arthroplasty are lower when antibiotic loaded cemented stems are utilized. Inspired by this technique, a point-of-care coating of antibiotic-loaded calcium sulfate (CaSO4) was applied to cementless revision stems in aseptic revision and 2nd stage reimplantation total hip arthroplasty. Methods: One hundred eleven consecutive femoral stems were coated. Just prior to insertion, 10 cc of CaSO4 was mixed with 1 g vancomycin and 240 mg tobramycin with the paste applied to the stem. The results were compared to a matched cohort (N = 104) performed across the previous 5 years. The surgical methods were comparable, but for the stem coating. The study group was followed for a minimum of 3 years. Results: In the study cohort of 111 patients, there were 69 aseptic revisions with one periprosthetic joint infection (PJI) (1.4%) and 42 second-stage reimplantations with 2 PJIs (4.8%). In the control cohort of 104 patients, there were 74 aseptic revisions with one PJI (1.4%) and 30 second-stage reimplantations with 7 PJIs (23.3%). There was no significant reduction in PJI rate in the aseptic revision subgroup (1.4% study vs 1.4% control group), P = 1.000. Antibiotic stem coating reduced PJI rate in the 2nd stage reimplantation subgroup (23.3% control vs 4.8% study group), P = .028. In both groups, there were no cases of aseptic stem loosening. Conclusions: Point-of-care antibiotic coating of cementless revision femoral stems reduces PJI infection rate in 2nd stage reimplantations only. We theorize that microbes persist in the endosteal cortices after resection and may contribute to infection recurrence.

Giant Cell Tumor of the Tendon Sheath of the Thumb: A Case Report.

The giant cell tumor of the tendon sheath (GCTTS) is a benign nodular tumor that is found on the tendon sheath of hands and feet. It is the second most common tumor of the hand, next only to ganglion cysts. Several hypotheses were formulated about the etiological factors of these tumors, but still, there is not a common opinion on etiology, prognostic factors, and recurrence rate. We report a case of GCTTS in a young male where a lesion was identified in his left thumb. Although marginal excision is the treatment of choice, it is often difficult to perform due to the location and the strict adherence of the tumor to the tendon or neurovascular bundles. The primary issue with the treatment lies in its elevated recurrence rates. Apart from cases of incomplete excision, there is a lack of consensus regarding the impact of other risk factors on the likelihood of recurrence.

Polidocanol sclerotherapy for the treatment of aneurysmal bone cyst, with or without pathological fractures: A prospective, comparative study.

Introduction: Polidocanol sclerotherapy in the treatment of aneurysmal bone cysts (ABCs) with or without pathological fractures has been a topic of debate. While some studies recommend intralesional curettage as the preferred treatment, others suggest intralesional sclerosants as an effective alternative. Material and methods: This study evaluates the use of polidocanol-based percutaneous sclerosant therapy in 28 patients with ABCs, of which 8 patients had pathological fracture. The patients received injections every four weeks based on clinical and radiological evaluation of the cyst, and the study assessed the results and complications of the treatment. Results: In group A (without pathological fractures), 14 out of 17 (82.4 %) lesions healed without any significant residual lesion. Three out of 17 (17.6 %) patients required further surgical intervention and were treated by curettage and bone grafting, definitively. Minor local inflammatory reaction was observed in 3 patients, which resolved without intervention within 3-4 days. In group B, all the 8 patients (100 %) with pathological fracture in their lesions healed as Grade 1 healing, without any significant residual lesion. One patient developed an episode of anesthesia related complication (delayed recovery) which resolved within an hour, without any residual effect. At final follow up, no recurrence was seen in any patient. Conclusion: The study concludes that polidocanol sclerotherapy is an effective treatment option for patients with ABCs, with or without pathological fractures, and has the potential to become the new treatment of choice for pathological fractures due to its low invasiveness, low morbidity, and affordability. However, further research is needed to confirm the efficacy of polidocanol sclerotherapy in larger patient populations and to compare its effectiveness with other treatment options.

Concomitant valgus hip osteotomy in operative fixation of displaced proximal femoral neck fractures.

Total hip arthroplasty (THA) is considered the preferred treatment for displaced proximal femoral neck fractures. However, in many countries this option is economically unviable. To improve outcomes in financially disadvantaged populations, we studied the technique of concomitant valgus hip osteotomy and operative fixation (VOOF). This prospective serial study compares two treatment groups: VOOF versus operative fixation alone with cannulated compression screws (CCSs). In the first series, 98 hip fixation procedures were performed using CCS. After fluoroscopic reduction of the fracture, three CCSs were placed. In the second series, 105 VOOF procedures were performed using a closing wedge intertrochanteric osteotomy with a compression lag screw and lateral femoral plate. The alignment goal was to create a modified Pauwel's fracture angle of 30°. After fluoroscopic reduction of fracture, lag screw was placed to achieve the calculated correction angle, followed by inter-trochanteric osteotomy and placement of barrel plate. Patients were followed for a minimum of two years. Mean follow-up was 4.6 years (4.1 to 5.0) in the CCS group and 5.5 years (5.25 to 5.75) in the VOOF group. The mean Harris Hip Score at two-year follow-up was 83.85 in the CCS group versus 88.00 in the VOOF group (p < 0.001). At the latest follow-up, all-cause failure rate was 29.1% in the CCS group and 11.7% in the VOOF group (p = 0.003). The total cost of the VOOF technique was 7.2% of a THA, and total cost of the CCS technique was 6.3% of a THA. The VOOF technique decreased all-cause failure rate compared to CCS. The total cost of VOOF was 13.5% greater than CCS, but 92.8% less than a THA. Increased cost of VOOF was considered acceptable to all patients in this series. VOOF technique provides a reasonable alternative to THA in patients who cannot afford a THA procedure.

Bilateral Distal Humeral Physeal Separation-From Birth Trauma to Family Trauma.

Introduction: Chondro-epiphyseal separation of the distal humerus is a rare injury, which can occur as a consequence of excessive traction on the upper extremity accompanying a dystocic birth or one complicated by cephalopelvic disproportion. Such fracture patterns can also result from a combination of rotatory and shear forces, also typically seen following child abuse. It can be easily mistaken for a posterior elbow dislocation, creating a delay in diagnosis. Since unossified cartilage cannot be seen radiographically, these injuries are better appreciated by ultrasound or magnetic resonance imaging. Case Report: We present a case of an 8-day-old neonate who presented with pseudoparesis of the left arm following birth. Posterior displacement of the elbow joint was identified on the radiograph. On ultrasound, a trans-physical supracondylar distal humerus fracture was identified. This was presumed as trauma secondary to a difficult delivery. At the 11th week of follow-up, the patient presented with a fracture of the right proximal tibia, followed by a fracture shaft left femur at 5 months of follow-up. Chest X-ray at this time revealed uniting rib fractures with callus formation. After ruling out any congenital collagen disorder (osteogenesis imperfecta), the patient was diagnosed with a case of battered baby syndrome. The case was reported to child protection services and parents were questioned and counseled for the same. Conclusion: This case report highlights the importance of a high degree of suspicion of child abuse in any child with a rare fracture pattern, uncommon serial fracture occurrence, and unconventional clinic-radiological presentation.

Extranodal Diffuse Large B-Cell Lymphoma (DLBCL) Presenting as Diffuse Joint Pain: A Diagnostic Dilemma.

Diffuse Large B-Cell Lymphoma (DLBCL) of bone is a rare presentation of Non-Hodgkin Lymphoma (NHL), which remains asymptomatic or present late in clinical course as bone pain or pathological fracture. We report a case of a 15-year-old male child presenting with diffuse joint pain and swelling over his left shoulder and elbow, associated with B symptoms. Radiological examination revealed lytic lesions in multiple bones along with collection along the left iliopsoas and hip joint, suggestive of infective etiology. The diagnostic dilemma was resolved on biopsy, which confirmed DLBCL involving bones and soft tissue.

CT scan analysis of implant mating comparing APA versus TEA in simultaneous bilateral TKA: One technique per knee.

BACKGROUND: The optimal landmark for setting femoral component rotation in primary TKA remains a debate. This study compares the Anterior-Posterior Axis (APA) versus the Transepicondylar Axis (TEA) in patients undergoing simultaneous bilateral TKA, where one reference line was randomized to each knee. Implant mating was assessed via post-operative CT scans. METHOD: The study included 32 patients with osteoarthritis in both knees with similar varus deformities. All patients underwent the same surgical procedure on both knees, aside from the selected femoral rotation axis line: APA randomized to one side and TEA to the contralateral. Post-operative CT scans were performed in extension to assess in-vivo mating. RESULTS: CT scan analysis showed mean rotation of the femoral implant externally rotated relative to the radiographic TEA with no significant difference between the APA and TEA groups (p = 0.28). Tibial implant rotation was also externally rotated to the radiographic TEA with no significant difference (p = 0.59). Femoral-tibial implant mating showed a mean external rotation of the tibia relative to the femur in both groups: 0.86 ± 4.0° external rotation in the APA group and 0.23 ± 3.7° external rotation in the TEA group. There was no significant difference between groups (p = 0.52). The range of mating mismatch was 15° in the APA group and 16.5° in the TEA group. CONCLUSIONS: When using a measured resection, posterior referencing technique, post-operative femoral-tibial implant mating measured by CT scan showed no superiority comparing the APA method versus the TEA method. LEVEL OF EVIDENCE: 2 Randomized prospective study.

Effectiveness of Ponseti technique in management of arthrogrypotic clubfeet - a prospective study.

BACKGROUND: Clubfoot constitutes roughly 70 percent of all foot deformities in arthrogryposis syndrome and 98% of those in classic arthrogryposis. Treatment of arthrogrypotic clubfoot is difficult and challenging due to a combination of factors like stiffness of ankle-foot complex, severe deformities and resistance to conventional treatment, frequent relapses and the challenge is further compounded by presence of associated hip and knee contractures. METHOD: A prospective clinical study was conducted using a sample of nineteen clubfeet in twelve arthrogrypotic children. During weekly visits Pirani and Dimeglio scores were assigned to each foot followed by manipulation and serial cast application according to the classical Ponseti technique. Mean initial Pirani score and Dimeglio score were 5.23 ± 0.5 and 15.79 ± 2.4 respectively. Mean Pirani and Dimeglio score at last follow up were 2.37 ± 1.9 and 8.26 ± 4.93 respectively. An average of 11.3 casts was required to achieve correction. Tendoachilles tenotomy was required in all 19 AMC clubfeet. RESULT: The primary outcome measure was to evaluate the role of Ponseti technique in management of arthrogrypotic clubfeet. The secondary outcome measure was to study the possible causes of relapses and complications with additional procedures required to manage clubfeet in AMC an initial correction was achieved in 13 out of 19 arthrogrypotic clubfeet (68.4%). Relapse occurred in 8 out of 19 clubfeet. Five of those relapsed feet were corrected by re-casting ± tenotomy. 52.6% of arthrogrypotic clubfeet were successfully treated by the Ponseti technique in our study. Three patients failed to respond to Ponseti technique required some form of soft tissue surgery. CONCLUSION: Based on our results, we recommend the Ponseti technique as the first line initial treatment for arthrogrypotic clubfeet. Although such feet require a higher number of plaster casts with a higher rate of tendo-achilles tenotomy but the eventual outcome is satisfactory. Although, relapses are higher than classical idiopathic clubfeet, most of them respond to re-manipulation and serial casting ± re-tenotomy.

Lactococcus garvieae Periprosthetic Joint Infection in a Cattle Rancher with a Total Knee Arthroplasty: A Novel Reservoir Transmission.

Introduction: Periprosthetic joint infection (PJI) remains a challenging complication of joint replacement surgery. With the more frequent use of immune modifying drugs and dietary changes in human populations, the resultant blunting of immune defenses allows for infections with less common organisms. Case Report: Lactococcus garvieae is an anaerobic, gram-positive coccus with reservoirs in fish and domesticated farm animals. Only two prior cases of PJI due to L. garvieae have been reported, both with reported marine transmission. We report a case of L. garvieae associated PJI in a cattle rancher with the first reported case of transmission from a bovine reservoir. The PJI was associated with intra-articular rice body formation, and the diagnosis confirmed with the aid of next generation DNA sequencing. A successful two stage exchange was performed. We propose a novel transmission mechanism with microbe entry via direct hematogenous inoculation during the patient's duties as a rancher. Conclusion: When an unusual organism is detected in a PJI, the treatment team should research the host reservoir(s) of the organism and correlate with the patient's exposure risk. While contamination of cultures is possible, a thorough investigation should be performed prior to that assumption. This reinforces the basic concept that a careful history remains vital when treating an unusual infection presentation. Next generation DNA sequencing is a useful confirmatory tool in establishing the offending organism. Lastly, the identification of rice bodies should raise suspicion for infection. Although not always associated with infection, efforts should be redoubled to identify or rule out a causative micro-organism(s).

Adaptive antimicrobial resistance, a description of microbial variants, and their relevance to periprosthetic joint infection.

Periprosthetic joint infection (PJI) is a difficult complication requiring a comprehensive eradication protocol. Cure rates have essentially stalled in the last two decades, using methods of antimicrobial cement joint spacers and parenteral antimicrobial agents. Functional spacers with higher-dose antimicrobial-loaded cement and antimicrobial-loaded calcium sulphate beads have emphasized local antimicrobial delivery on the premise that high-dose local antimicrobial delivery will enhance eradication. However, with increasing antimicrobial pressures, microbiota have responded with adaptive mechanisms beyond traditional antimicrobial resistance genes. In this review we describe adaptive resistance mechanisms that are relevant to the treatment of PJI. Some mechanisms are well known, but others are new. The objective of this review is to inform clinicians of the known adaptive resistance mechanisms of microbes relevant to PJI. We also discuss the implications of these adaptive mechanisms in the future treatment of PJI. Cite this article: Bone Joint J 2022;104-B(5):575-580.

Outcomes of Second-stage Reimplantation After Modular Knee Arthrodesis for Periprosthetic Joint Infection.

BACKGROUND: Modular knee arthrodesis (MKU) is a salvage treatment for recurrent periprosthetic joint infection (PJI) or PJI associated with notable bone loss. Reimplantation endoprosthetic reconstruction (REI) is an option in patients with MKU who have PJI clearance but are not satisfied with pain or functional outcomes with MKU. The purpose of this study was to evaluate the outcomes of MKU to REI conversion. METHODS: This was a single-center retrospective cohort study of 56 patients who underwent MKU to REI from 2010 to 2019. All patients were staged according to the McPherson staging system. An infecting organism was documented based on pre-MKU aspiration or intraoperative cultures at the time of MKU. Rate ratios were calculated for relevant patient factors. Rate ratios were calculated using Poisson regression with a log link. RESULTS: The mean REI patient age was 67 years, most of the patients were McPherson B hosts (62.5%) with a type 2 (46.4%) or type 3 (51.8%) limb score, and all PJI were chronic. The most common infecting organisms at the time of MKU were Staphylococcus epidermidis (23.2%) and Staphylococcus aureus (23.2%, MSSA 14.3%, MRSA 8.9%). The mean time from MKU to REI was 220 days. An 8.9% REI index hospitalization complication rate and a 21.4% overall complication rate (excluding reinfection) were observed. Sixty-seven percent of the patients remained infection-free at an average follow-up of 37 months, among those there was 96.4% implant survivorship. No notable association was observed between index PJI organism or McPherson staging and REI failure secondary to PJI. DISCUSSION: Approximately two thirds of patients who undergo conversion from MKU to REI have infection-free survival at the midterm follow-up. An index infecting organism and a McPherson host type do not seem to be markedly associated with reinfection risk. These findings help guide expectations of PJI MKU conversion to REI.

Biphasic bone graft substitute in revision total hip arthroplasty with significant acetabular bone defects : a retrospective analysis.

AIMS: Large acetabular bone defects encountered in revision total hip arthroplasty (THA) are challenging to restore. Metal constructs for structural support are combined with bone graft materials for restoration. Autograft is restricted due to limited volume, and allogenic grafts have downsides including cost, availability, and operative processing. Bone graft substitutes (BGS) are an attractive alternative if they can demonstrate positive remodelling. One potential product is a biphasic injectable mixture (Cerament) that combines a fast-resorbing material (calcium sulphate) with the highly osteoconductive material hydroxyapatite. This study reviews the application of this biomaterial in large acetabular defects. METHODS: We performed a retrospective review at a single institution of patients undergoing revision THA by a single surgeon. We identified 49 consecutive patients with large acetabular defects where the biphasic BGS was applied, with no other products added to the BGS. After placement of metallic acetabular implants, the BGS was injected into the remaining bone defects surrounding the new implants. Patients were followed and monitored for functional outcome scores, implant fixation, radiological graft site remodelling, and revision failures. RESULTS: Mean follow-up was 39.5 months (36 to 71), with a significant improvement in post-revision function compared to preoperative function. Graft site remodelling was rated radiologically as moderate in 31 hips (63%) and strong in 12 hips (24%). There were no cases of complete graft site dissolution. No acetabular loosening was identified. None of the patients developed clinically significant heterotopic ossification. There were twelve reoperations: six patients developed post-revision infections, three experienced dislocations, two sustained periprosthetic femur fractures, and one subject had femoral component aseptic loosening. CONCLUSION: Our series reports bone defect restoration with the sole use of a biphasic injectable BGS in the periacetabular region. We did not observe significant graft dissolution. We emphasize that successful graft site remodelling requires meticulous recipient site preparation.Cite this article: Bone Jt Open 2022;3(12):991-997.