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.

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.

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.

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.

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.

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.

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.

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.

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.

Simulated large joint fluid model for evaluating intra-articular antibiotic delivery systems: initial evaluation using antibiotic-loaded calcium sulfate beads.

Introduction: Local antimicrobial delivery via calcium sulfate (CaSO 4 ) beads is used as an adjunctive treatment for periprosthetic joint infection. There is limited clinical information describing the performance of antimicrobial-loaded CaSO 4 (ALCS) in large-scale applications. We developed a simulated large joint model to study properties of eluting ALCS. Methods: The in vitro testing platform was an adapted standardized model for tribological testing of prosthetic total hips and total knees (ASTM F732). The model was 70 mL total fluid volume, 25 % bovine serum, and 75 % phosphate-buffered saline, using ISO standard 14242-1 for human synovial fluid simulation. Four brands of CaSO 4 were evaluated. Each 10 mL of CaSO 4 was loaded with 1.2 grams (g) of tobramycin and 1 g of vancomycin powders. A 35 mL bead volume, equaling 175 beads, of each product was placed in incubated flasks. The test period was 6 weeks with scheduled interval fluid exchanges. Fluid samples were tested for antibiotic and calcium concentrations and pH. Results: Antibiotic elution showed an initial burst on Day 1, followed by a logarithmic reduction over 1 week. Tobramycin fully eluted within 2.5 weeks. Vancomycin showed sustained release over 6 weeks. Calcium ion concentrations were high, with gradual decrease after 3 weeks. All four CaSO 4 products were inherently acidic. Fluid became more acidic with the addition of antibiotics primarily driven by vancomycin. Discussion: Clinicians should be cognizant of tobramycin elution burst with ALCS in large loads. The main driver of acidic pH levels was vancomycin. We propose that joint complications may result from lowered fluid acidity, and we suggest clinical study of synovial pH.

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.

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.

Outcomes of Modular Knee Arthrodesis for Challenging Periprosthetic Joint Infections.

BACKGROUND: Modular knee arthrodesis (MKA) is a salvage treatment option for patients with challenging periprosthetic joint infections (PJI). The purpose of this study was to investigate the outcomes of patients who underwent MKA for PJI with a single technique and determine if specific factors are associated with MKA failure. METHODS: This was a retrospective review of 81 patients who underwent MKA at a single institution. Knee Society Scores were recorded before MKA and at the final follow-up (mean 52 months). Poisson regression was used to calculate rate ratios for MKA failure secondary to infection. RESULTS: The mean patient age was 67 years; most patients were McPherson B hosts (56.8%) and had type 3 extremities (53.1%), and all had a type III infection (chronic, >4 wks). Forty-six percent of patients had a prior explantation (59.5% failed 2-stage, 40.5% failed spacer). Staphylococcus epidermidis and Staphylococcus aureus were the most common organisms, 22.2% and 18.5%, respectively. Thirty percent of patients had at least one reoperation, excluding reimplantation (14.8% irrigation and debridement/wound closure, 9.9% MKA exchange, and 7.4% amputation). Of 82.7% of MKA patients with no evidence of infection, 82.1% (56 patients) underwent reimplantation endoprosthetic reconstruction, and 67.3% of these remained infection-free at the final follow-up. DISCUSSION: MKA is a salvage option for challenging PJI cases that may serve as definitive surgical management or as a bridge to endoprosthetic reconstruction for patients who have failed prior infection control procedures.

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).

Fabrication of antibiotic-loaded dissolvable calcium sulfate beads: an in vitro mixing lab utilizing various antibiotic mixing formulas.

Chronic periprosthetic joint infection (PJI) is a devastating complication that requires an aggressive eradication protocol. Local antimicrobial delivery via dissolvable calcium sulfate (CaSO 4 ) using small-sized beads (3-8 mm) has been utilized as an adjunctive treatment combined with implant exchange, radical debridement, and antimicrobial loaded acrylic spacers. The non-exothermic setting of CaSO 4 theoretically allows for any antimicrobial agent to be used, so long as mixing methods provide a consistent fabrication within a reasonable set time. This study performed the first in vitro mixing study, in which various antimicrobial agents, used singularly and in combination, were mixed with a synthetic CaSO 4 product to observe and document their interactions. The study was performed in a simulated operating room environment. We report a standard mix formula with set times, testing 22 different antimicrobial agents, combinations, and doses. For some antimicrobials and combinations, set times using the standard formula were either too fast or exceedingly slow. For these 14 antimicrobial agents and combinations, we were able to arrive at individualized mixing methods. We present all mixing formulas and set times. In all, we were able to establish mixing methods that incorporate all antimicrobial agents and combinations that we have seen utilized via surgeon-directed use.

The Expanding Role of Biomarkers in Diagnosing Infection in Total Joint Arthroplasty: A Review of Current Literature.

Consistent diagnosis of periprosthetic infection in total joint arthroplasty continues to elude the orthopedic surgeon because no gold standard test exists. Therefore clinicians must rely on a combination of tests to help aid the diagnosis. The expanding role of biomarkers has shown promising results to more accurately diagnose an infection when combined with clinical suspicion and bacterial culture testing. This paper reviews the diagnostic capabilities of the most current serum and synovial biomarkers as well as next generation sequencing in the setting of periprosthetic joint infection. Future research and high-powered studies will be necessary to determine sensitivity and specificity of each biomarker.

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.

Periosteal pseudotumor in complex total knee arthroplasty resembling a neoplastic process.

This case report describes in detail an erosive distal diaphyseal pseudotumor that occurred 6 years after a complex endoprosthetic hinge total knee arthroplasty (TKA). A female patient had conversion of a knee fusion to an endoprosthetic hinge TKA at the age of 62. At her scheduled 6-year follow-up, she presented with mild distal thigh pain and radiographs showing a 6-7 cm erosive lytic diaphyseal lesion that looked very suspicious for a neoplastic process. An en bloc resection of the distal femur and femoral endoprosthesis was performed. Histologic review showed the mass to be a pseudotumor with the wear debris emanating from within the femoral canal due to distal stem loosening. We deduce that mechanized stem abrasion created microscopic titanium alloy particles that escaped via a small diaphyseal crack and stimulated an inflammatory response resulting in a periosteal erosive pseudotumor. The main lesson of this report is that, in the face of a joint replacement surgery of the knee, pseudotumor formation is a more likely diagnosis than a neoplastic process when encountering an expanding bony mass. Thus, a biopsy prior to en bloc resection, would be our recommended course of action any time a suspicious mass is encountered close to a TKA.