Introduction

Success rate after Debridement-Irrigation, Antibiotic Therapy and Implant Retention (DAIR) for treatment of Acute Haematogenous (AH) and Early Post-surgical (EP) periprosthetic joint infection (PJI) varies widely among published studies. Prosthesis exchange is recommended to treat PJI after a failed DAIR. However, no early postoperative prognostic factors permitting to identify future failures have been described.

Aim

Cutibacterium acnes, a skin commensal, is responsible for 5–10% of prosthetic joint infections (PJI). All current microbiological definitions of PJI require two or more identical commensal isolates to be recovered from the same procedure to diagnose PJI and rule out contamination. Unlike coagulase negative staphylococci, C.acnes shows a highly stereotypical susceptibility profile making impossible to phenotypically assess the clonal relationship of isolates. In order to determine the clonal relationship of multiple C.acnes isolates recovered from arthroplasty revisions, we analyzed by multi-locus sequence typing (MLST) C.acnes isolates grown from orthopedic device-related infections (ODRI) in a reference center for bone and joint infection.

Aim

The frequency of arthroplasty among older people is increasing. Taking care of Prosthetic Joint infection (PJI) in this specific population is a challenge. The purpose of this multicentric retrospective study was to evaluate the bacterial epidemiology of hip and knee PJI in octogenarians and nonagenarians over ten years.

Aim

According to Tsukuyama classification, late acute hematogenous prosthesis joint infections (PJI) should be treated with debridement and implant retention (DAIR). We report here a recurrent Salmonella Dublin hip prosthesis infection. Through this case, we show how a recurrence of chronic PJI may have an acute clinical presentation leading to an inadequate surgical treatment.

Aim

Propionibacterium acnes is a skin commensal colonizing the deeper structures of the pilous bulb. It is responsible for 5–10% of lower limb prosthetic joint infections (PJI) but accounts for as many as 50% of shoulder arthroplasty infections. P. acnes PJIs characteristically feature limited systemic inflammation, limited polymorphonuclear infiltration and clinical signs compatible with aseptic loosening. All current microbiological definitions of PJI require two or more identical commensal isolates to be recovered from the same procedure to diagnose PJI to increase specificity and rule out contamination. Whereas the antimicrobial susceptibility patterns of coagulase negative staphylococci are highly polymorphic and commonly allow the ready distinction of unrelated strains, P. acnes shows a highly stereotypical susceptibility profile and it is impossible to phenotypically assess the clonal relationship of isolates. In order to determine the clonal relationship of multiple P. acnes isolates recovered from arthroplasty revisions, we analyzed by multi-locus sequence typing (MLST) P. acnes isolates grown from PJI in a reference center for bone and joint infection.

The diagnosis of prosthetic joint infections (PJI) represents a critical challenge for orthopedic surgeons and infectious disease specialists. The diagnosis of PJI is often delayed because non-invasive assays lack sensitivity and specificity. A novel multiplex immunoassay detecting antibodies against Staphylococci, Propionibacteria and Streptococcus agalactiae was developed and its performance evaluated in a prospective, multicenter, non-interventional study.

The Luminex-based assay measures serum IgG against a proprietary panel of recombinant purified antigens from Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus agalactiae and Propionibacterium acnes. Patients undergoing revision arthroplasty were included over a 2-year period (from 2012 up to 2014) in two French reference centers in compliance with IRB and French regulations. PJI cases were defined microbiologically (≥2 intraoperative samples yielding the same microorganism) for confrontation of microbiological and immunoassay data.

455 patients were eligible for study analyses. 149 patients (32.7%) were found to be infected. Among the most frequent infecting species recovered were S. aureus (30%), S. epidermidis (26%), P. acnes (9%), S. lugdunensis (6%), and S. agalactiae (4%). The sensitivity and specificity values of the test were, respectively, 75.9% (63/83) and 82.2% (180/219) for staphylococci (S. aureus, S. epidermidis, S. lugdunensis), 38.5% (5/13) and 81.9% (190/232) for P. acnes, and 66.7% (4/6) and 92.4% (208/225) for S. agalactiae. Interestingly, all cases (9/9) involving S. lugdunensis were detected by the test and the sensitivity for S. epidermidis reached 79.4% in patients more than three months after joint replacement. In a similar fashion, 89.5% (17/19) in the subpopulation with elevated inflammatory markers (ESR>30 and CRP>10).

The assay correctly identified 67% of the microbiologically positive patients that were negative by ESR or CRP screening.

This novel multiplex serological test allows the rapid and non-invasive diagnosis of the most frequent PJI pathogens, showing a good correlation with microbiological culture. and appears to be a new promising tool in the management of PJI, adding sensitivity to the current serological assays and enhancing the management of patients with pauci-inflammatory PJI.

Introduction

Modular femoral necks have shown promising clinical results in total hip arthroplasty (THA) to optimize offset, rotation, and leg length. Given the wide variety of proximal femoral morphology, fine-tuning these kinematic parameters can help decrease femoroacetabular impingement, decrease wear rates and help prevent dislocations. Yet, additional implant junctions introduce additional mechanisms of failure. We present two patients who developed an abnormal soft tissue reaction consistent with a metal hypersensitivity reaction at a modular femoral neck/stem junction requiring revision arthroplasty.

Background

Both from experimental studies and the large arthroplasty registries there is evidence that bacteria are more often involved in implant loosening then is currently reported. To further elucidate this potential problem, the current study investigated the hypothesis that many total hip arthroplasty revisions, classified as aseptic, are in fact low-grade infections missed with routine diagnostics.

Purpose of the study: Different metatarsal osteotomies performed via a percutaneous approach can be used to correct hallux valgus. The purpose of this work was to analyse the clinical and radiographic results of percutaneous treatment of hallux valgus using a distal wedge osteotomy of the metatarsal.

Material and methods: This was a consecutive prospective series of 125 cases of hallux valgus treated by the same surgical technique, distal wedge osteotomy of the metatarsal without fixation. Percutaneous lateral arthrolysis and percutaneous varus correction of the first phalanx were associated. The AOFAS function score for the forefoot was determined preoperatively and at last follow-up. Time to normal shoe wearing and to resumption of occupational activities were also noted. Angle correction was determined on the anteroposterior weight-bearing image. All patients were reviewed at mean 20 months (range 12–40).

Results: The AOFAS forefoot function score was 46/100 preoperatively and 87/100 at last follow-up. Mean motion of the metatarsophalangeal joint was 95 preoperatively and 80 postoperatively. Mean metatarsophalangeal valgus was 30 preoperatively and 12 at last follow-up. The mean intermetatarsal angle improved from 13 to 8 and the orientation of the joint surface of the first metatarsal (DMAA) improved from 11 to 7. The metatarsophalangeal joint of the first ray was congruent in 45% of the feet preoperatively and in 88% postoperatively. Mean time to wearing normal shoes was seven weeks for the treatment of hallux valgus alone and three months for surgery of the first ray and lateral rays.

Discussion: Percutaneous treatment of mild to moderate hallux valgus by distal wedge osteotomy of the metatarsal enables good clinical and radiographic improvement. The surgical technique requires experience with percutaneous surgery of the forefoot to avoid the main complications: secondary displacement in elevates and excessive shortening of the first metatarsal. This technique restores metatarsophalangeal congruence of the first ray compared with Isham-Reverdin osteotomy.

Purpose of the study: The purpose of this work was to analyse the results of infection in patients with joint prostheses implanted after septic arthritis, distinguishing evolving versus cured arthritis.

Material and methods: This was a retrospective series of 70 cases of septic arthritis (in 69 patients) including 7 patients with mycobacterial infections and 63 patients with ordinary germ infections. For the seven mycro-bacterial infections (five Mycobacterium tuberculosis and two Mycobacterium xenopi), the arthroplasty was implanted on evolving arthritis and in two on arthritis considered cured. For the 63 cases of common germs (70% staphylococcal infections), the septic arthritis was considered evolving in 36 and cured in 27. For half of the cases, the arthritis was blood-borne and localised in the knee. For cases considered evolving, the arthroplasty was generally a two-phase procedure (32/36 cases). Adapted antibiotics were associated for 93 days on average (45–180). For arthritis considered cured, the arthroplasty was implanted on average 53 months (range 6–700) after the infectious episode, generally in a one-phase procedure (22/27). Adapted antibiotics were associated for 80 days on average in seven patients because of positive intraoperative samples. One patient was lost to follow-up before two years and all others were reviewed with at least two years follow-up (mean 5 years, range 2–13 years).

Results: For the seven cases of mycobacterial arthritis, one patient was lost to follow-up, six had no signs of infection at mean 7 years follow-up. For the other cases, 89% of patients who had a prosthesis for evolving arthritis were considered as cured, 6% relapsed before 18 months and 6% presented a new infection with a different germ. For arthroplasty after assumed cured arthritis, 81% of patients were considered cured, 15% relapsed before 18 months and 4% presented a new infection with another germ.

Discussion: Arthroplasty is the treatment of choice for septic evolving septic arthritis, enabling cure in more than 80%, irrespective of the causal germ, and whether cure of the infection was apparently achieved or not.

Purpose of the study: We present our experience with the distal-based sural flap for lower leg tissue defects.

Material and methods: This consecutive retrospective series included 45 flaps in 45 patients, 36 men and 9 women, mean age 50 years. The size and the cause of the tissue loss were described as were the patients’ history and risk factors. The distally-based fasciocutaneous sural flap was used in all cases. The postoperative period as well as the quality of the final cover were analyzed.

Results: At mean follow-up of 45 months, 43 of the 45 faciocutaneous flaps survived. Cover of initial tissue defect was complete in 41 cases and partial in two. Two flaps failed, leading to limb amputation. For the 25 patients with no risk factor, all flaps resulted in perfect tissue cover. In the 20 patients with risk factors, perfect cover was achieved for 16; only 10 of 20 flaps had an uneventful history with simple healing process; partial necrosis developed in eight flaps and two flaps failed.

Discussion: The Distally-based fasciocutaneous sural flap is a very reliable method offering many possibilities for covering lower limb tissue loss from the upper third of the leg to the ankle and hindfoot. The limitations are patient-related. There are thus many indications. For bone infections, one stage tissue cover can be achieved by integrating the flap as part of the overall treatment for the bone-related injury. This flap has an excellent vascular supply which increases the local concentration of systemic antibiotics. The distally-based sural flap can also be used successfully in traumatology.

Conclusion: The distally-based sural flap is reliable and relatively easy to perform. It provides excellent cover for most tissue losses situated on the lower half of the leg and ankle. The limitations are patient-related.

Purpose of the study: When infection occurs on solid bone tissue, the problems which arise concern filling the bony defect, achieving effective antibiotic therapy at the bone level, and correct cutaneous coverage. We present our experience in the management of 80 cases of bone infection on continuous bone tissue of the lower limb.

Material and methods: This was a retrospective series of 80 cases of bone infection on continuous bone in the lower limb in 77 patients, mean age 45 years. The infection had on average persisted for 13 years and the patients had undergone on average six operations at the infected site. Bone infection was a posttraumatic complication in three-quarters of the cases and localized in the tibia in half. The general and local status was assessed for each patient using the Cierny-Mader classification. All patients underwent surgery using the same operative protocol: resection, filling, bone cutaneous cover. We describe the different operative phases and the techniques employed. Patients free of clinical or biological signs of recurrent infection two years after hospital management were considered cured.

Results: All patients were reviewed, there were no patients lost to follow-up. At mean follow-up of four years, 81% of patients were considered cured. Recurrent infection was observed in 14% of cases, requiring revision on average two years after initial management. For 5% of the cases, the initial treatment failed and was followed by amputation. Poor general or local status and extensive diffuse osteitis were factors predictive of poor cure of the infection.

Discussion: We discuss the different causes and pathogenic mechanisms of osteitis on continuous bone. Surgical techniques are compared. Bone infection on continuous bone is an ideal indication for muscle or fas-ciocutaneous flaps for filling bone cavities and achieving cutaneous cover. The different modalities and duration of antibiotic therapy are discussed.

Conclusion: Bone infection on continuous bone is a specific often poorly individualized clinical situation. A specific surgical protocol is indicated to fill bony defects, and achieve cutaneous cover and thus definitive cure.

The purpose of this study was to evaluate trabecular bone response to four different synthetic graft materials (CaSO₄ and CaSO₄ – HA/TCP composites) as compared to autograft in a canine defect model. The group with the highest HA/TCP proportion (and the lowest CaSO4 proportion) had the greatest amount of residual graft material and total mineralized material (p< 0.05). Increasing the proportion of HA/TCP reduces the rate of dissolution, and appears to have little effect on bone formation. This study suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications.

Calcium sulfates and phosphates have become popular clinically for use as bone graft substitutes, however, their in-vivo performance has not been well characterized. The purpose of this study was to evaluate trabecular bone response to four synthetic graft materials (CaSO₄ and CaSO₄ – HA/TCP composites) as compared to autograft in a canine defect model.

Both 100% CaSO₄ and the 3 CaSO₄– HA/TCP formulations showed good bone formation. The group with the highest proportion of HA/TCP lasted longer than the other formulations, suggesting increased HA/TCP proportions reduce the rates of dissolution, without compromising bone formation in the current model.

Results suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications.

In this REB-approved RCT, bilateral humeral and femoral cylindrical defects were filled with one of four types of pellets with varying proportions of CaSO₄ – HA/TCP, autograft bone, or left unfilled. After sacrifice at six or twelve weeks, defect sites were evaluated histologically for tissue and inflammatory response, area fractions of residual graft material, and bone ingrowth in the defects.

The area of the defect occupied by residual graft material in the group with the highest percentage of HA/TCP was greater than in other composite groups (p< 0.0006). At twelve weeks, this group contained more total mineralized material (graft material + bone) (p< 0.005). The extent of new bone formation was not different among the composite groups at either time-point, but all showed more bone formation than the empty defect.

Funding: This study was funded by a research grant from Stryker Howmedica, Matwah, NJ.

Introduction and Aims: Calcium sulfates and phosphates have become popular as bone graft substitutes, however, their in-vivo performance has not been well characterised. The purpose of this study was to evaluate trabecular bone response to four synthetic graft materials (CaSO4 and CaSO4 – HA/TCP composites) as compared to autograft in a canine defect model.

Method: In this REB-approved RCT, bilateral humeral and femoral cylindrical defects were filled with one of four types of pellets with varying proportions of CaSO4 – HA/TCP, autograft bone, or left unfilled. After sacrifice at six or 12 weeks, defect sites were evaluated histologically for tissue and inflammatory response, area fractions of residual graft material, and bone ingrowth in the defects.

Results: The area of the defect occupied by residual graft material in the group with the highest percentage of HA/TCP was greater than in other composite groups (p< 0.0006). At 12 weeks, this group contained more total mineralised material (graft material + bone) (p< 0.005). The extent of new bone formation was not different among the composite groups at either time-point, but all showed more bone formation than the empty defect. Both 100% CaSO4 and the 3 CaSO4 – HA/TCP formulations showed good bone formation.

Conclusion: The group with the highest proportion of HA/TCP lasted longest, suggesting increased HA/TCP proportions reduce the rates of dissolution, without compromising bone formation in this model. Results suggest that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications.

Purpose: We report results of management of infected total knee arthroplasty (TKA). Our aim was to analyse the different therapeutic options and identify factors predictive of cure.

Material and methods: This retrospective multicentric analysis included a consecutive series of 179 cases of infected TKA. Revision TKA was performed for 77 knees in two operative times, 30 in one operative time. Synovecetomy was performed for 26 knees, arthrodesis for 36 and amputation for nine. Minimum follow-up was two years. For each case, we assessed cure of infection and functional outcome. Non-parametric statistical tests were used to compare outcome.

Results: Mean follow-up was 41.2 months. There was a 17% death rate during the first two years after management of infected TKA. Cure was achieved in two-thirds of the revised cases (in one or two operative times) and in 54% of the synovectomy cases. Arthrodesis yielded cure in 50%. Staphylococci was identified in 65%. The functional outcomes of revised prostheses (two times) was less satisfactory if the anterior tibial tubercle was removed, if the extensor system was involved, or if a flap cover was necessary (p< 0.05). There was no significant difference in functional outcome for one-time and two-time operations. Cure was achieved in 95% of the synovectomies performed before 16 days. Relapse occurred in 95% of those performed after 56 days. Arthrodesis performed in patients with major bone loss failed. Among the arthrodesis failures, 50% were related to mechanical failure and the other 50% to recurrent infection.

Discussion: We discuss these results and indications for different treatments of infected total knee arthroplasty. For each therapeutic option, we analysed factors allowing hope for cure and good functional outcome.

Conclusion: The objective of treatment of an infected TKA is to achieve cure and maintain satisfactory function, often a difficult goal to reach. Major mutilating surgery can be avoided by early adapted care.

Purpose: The purpose of this work was to define clinical and microbiological criteria allowing the distinction of postoperative infections of joint implants from secondary infections and to propose a probability score.

Material and methods: This retrospective multicentric study was conducted on 134 cases of infections of hip and knee prostheses. The first step was to distinguish three populations of infections (postoperative, secondary, unknown) based on the germ isolated at diagnosis of prosthesis infection (coagulase-negative Staphylococus, other germs, and Staphylococcus aureus respectively). The second step was to analyse clinical features in the group of postoperative infections and in the group of secondary infections in order to evaluate the predictive value of each of the following parameters: infection-free period, time to infection, distant focus.

Results: Fifty-seven cases of secondary infections were identified. There were 34 cases of postoperative infection and 43 cases of infection of unknown category (Staphylococcus aureus infections). The diagnosis of prosthesis infection was retained on the basis of intraoperative samples in 81% of the cases. The infection-free period was less than 1 year (time between implantation and first joint signs) in 69% of the cases of postoperative infection and in 36% of the cases of secondary infection. The difference was significant (p=0.003). A distant focus of infection was found in 44% of the cases (and documented by a bacteriological sample in 13%, 18/134). An invasive therapeutic procedure was identified in 12% (4/34) of the postoperative infections and in 56% (32/57) of the secondary infections. The difference was significant.

Discussion: The duration of the infection-free period and the notion of a distant focus of infection (documented or not) are significant criteria enabling a distinction between postoperative and secondary infections after prosthesis implantation. The notion of time to infection (time between the infectious episode and diagnosis of infected prosthesis) is not a significant criteria for identifying secondary infection (p > 0.005). Staphylococcus aureus infection remains difficult to classify.

Conclusion: Analysis of clinical features as a function of the microbiological findings enabled identification of significant criteria of secondary infection of joint prostheses. This enables proposing a probability score to be evaluated on a larger scale.