Why does radial head arthroplasty fail today? A systematic review of recent literature.

Since the introduction of the radial head prosthesis (RHP) in 1941, many designs have been introduced. It is not clear whether prosthesis design parameters are related to early failure. The aim of this systematic review is to report on failure modes and to explore the association between implant design and early failure.A search was conducted to identify studies reporting on failed primary RHP. The results are clustered per type of RHP based on: material, fixation technique, modularity, and polarity. Chi-square tests are used to compare reasons for failure between the groups.Thirty-four articles are included involving 152 failed radial head arthroplasties (RHAs) in 152 patients. Eighteen different types of RHPs have been used.The most frequent reasons for revision surgery after RHA are (aseptic) loosening (30%), elbow stiffness (20%) and/or persisting pain (17%). Failure occurs after an average of 34 months (range, 0-348 months; median, 14 months).Press-fit prostheses fail at a higher ratio because of symptomatic loosening than intentionally loose-fit prostheses and prostheses that are fixed with an expandable stem (p < 0.01).Because of the many different types of RHP used to date and the limited numbers and evidence on early failure of RHA, the current data provide no evidence for a specific RHP design. Cite this article: EFORT Open Rev 2019;4:659-667. DOI: 10.1302/2058-5241.4.180099.

Radiocapitellar prosthetic arthroplasty: short-term to midterm results of 19 elbows.

BACKGROUND: Few studies have discussed the short-term results of radiocapitellar (RC) prosthetic arthroplasty (PA). In this study, we assessed the short-term to midterm functional and radiographic results of elbows after RC PA. Our secondary aim was to assess the survival of the RC PA. METHODS: We included 19 elbows in 18 patients with a mean follow-up of 35 months (range, 12-88 months). Patients were examined for instability and range of motion and were assessed using Mayo Elbow Performance Index and Oxford Elbow Score at any subsequent visits. RC PA was the primary treatment in 16 elbows, and 3 were revision radial head arthroplasty with concomitant capitellar resurfacing. RESULTS: Range of motion, pain, and functional scores improved significantly from the preoperative to the final follow-up visit. Categoric grouping of the final Mayo Elbow Performance Index outcome scores showed 9 excellent, 5 good, 3 fair, 0 poor, and 2 missing data. However, stability of the elbow remained unchanged. There was no pain in 11 patients, mild pain in 5, and moderate pain in 3. Radiographic assessment showed no significant progress in ulnohumeral arthritis, although 3 elbows showed osteoarthritis progression to a higher grade. There were no major complications, including infection, revision, disassembly of the components, or conversion to total elbow arthroplasty. Survival of the RC PA was 100%. CONCLUSION: Elbow arthritis seems to become stationary after RC PA. Symptomatic RC osteoarthritis would probably benefit from RC PA regardless of the etiology.

Radial Head Arthroplasty: A Systematic Review.

BACKGROUND: Despite the expanding body of literature on radial head arthroplasty, the increasing understanding of elbow anatomy, biomechanics, and kinetics, and the evolution of surgical techniques and prosthesis designs, there is currently no evidence to support one type of radial head prosthesis over another. The purposes of the present report were to review the literature and to explore the association between prosthesis design variables and the timing of surgery and the outcome of modern radial head arthroplasty. METHODS: The literature search was limited to studies involving skeletally mature patients. Major databases were searched from January 1940 to May 2015 to identify studies relating to functional and subjective outcomes and radiographic results after radial head arthroplasty. RESULTS: Thirty articles involving 727 patients were included. Seventy percent of the implants were made of cobalt-chromium, 15% were made of pyrocarbon, 9% were made of titanium, and 6% were made of Vitallium. Seventy percent were monopolar, and 30% were bipolar. Twenty-one percent were cemented in place, 32% were press-fit, 32% were intentionally loose-fit, and 15% were fixed with an expandable stem. The weighted average duration of follow-up was 45 months. The rate of revision ranged from 0% to 29% among studies. The incidence of revision was 8% during 2,714 person-years of follow-up across all 727 patients, yielding a crude overall revision rate of 2.06 per 100 person-years of follow-up. The revision rate was not significantly affected by prosthesis polarity, material, or fixation technique, nor was it significantly affected by the delay of treatment. There was also no significant effect of prosthesis polarity, material, or fixation technique on postoperative range of motion. The Mayo Elbow Performance Score was only reported for half of the overall patient population, but, among those patients, the combined rate of excellent and good results was 85%. Seven percent of the overall patient population underwent secondary surgery about the elbow other than revision surgery. Twenty-three percent were reported to have 1 or more complications. CONCLUSIONS: On the basis of our analysis of the peer-reviewed English-language literature on radial head arthroplasty from January 1940 to May 2015, there seems to be no evidence to support one type of radial head prosthesis over another. The only exception is that silicone prostheses have been shown to be biologically and biomechanically insufficient. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Cemented bipolar radial head arthroplasty: midterm follow-up results.

BACKGROUND: Theoretical advantages of bipolar over monopolar radial head arthroplasty include better accommodation of radiocapitellar malalignment, reduction of capitellar abrasion, and reduction of stress at the bone-to-cement and cement-to-implant interfaces. Our purpose was to report the midterm results of cemented bipolar radial head arthroplasty. METHODS: Twenty-five patients were treated by cemented bipolar radial head arthroplasty for acute fracture of the radial head, earlier treatment that had failed, or posttraumatic sequelae. One patient refused follow-up after surgery. Results are presented for the remaining 24 patients. RESULTS: At a mean follow-up of 50 months (range, 24-72 months), 1 prosthesis (4%) had been removed 2 years after implantation for dissociation of the prosthesis due to failure of the snap-on mechanism. There were 2 (8%) additional radiologic failures in the subluxated position: 1 prosthesis due to malalignment of the radius onto the capitellum and another due to ulnohumeral erosion. The average flexion-extension arc was 129° (range, 80°-140°), and the average pronation-supination arc was 131° (range, 40°-180°). According to the Mayo Elbow Performance Score, the combined excellent and good results accounted for 83%. In 8 patients, the bipolar design compensated for radiocapitellar malalignment. CONCLUSIONS: The overall midterm outcome of this series of 25 cemented bipolar radial head arthroplasties can be considered favorable. There was 1 (4%) revision and 2 (8%) additional radiologic failures. The bipolar design was able to compensate for radiocapitellar malalignment. We suggest considering a cemented bipolar radial head prosthesis in case of concerns about radiocapitellar alignment.

Press-fit bipolar radial head arthroplasty, midterm results.

BACKGROUND: Theoretical advantages of bipolar compared with monopolar radial head arthroplasty include better accommodation of radiocapitellar malalignment, reduction of capitellar abrasion, and reduction of stress at the bone-implant interfaces. Our purpose was to report the midterm results of press-fit bipolar radial head arthroplasty. METHODS: Thirty patients were treated by press-fit bipolar radial head arthroplasty for acute fracture of the radial head, failed earlier treatment, or post-traumatic sequelae. Three patients were lost to follow-up. Results are presented for the remaining 27 patients. RESULTS: At mean follow-up of 48 months (range, 28-73), there had been 3 (11%) revisions. Two involved conversion to prosthetic radiocapitellar hemiarthroplasty for symptomatic capitellar abrasion; a third involved exchange of the articular component (ie, head) for instability. In all, the stems appeared well fixed. A prosthesis in a subluxed position accounted for the 1 (4%) additional radiologic failure. The average flexion-extension arc was 136° (range, 120°-145°), and the average pronation-supination arc was 138° (range, 70°-180°). According to the Mayo Elbow Performance Score, the combined excellent and good results accounted for 70%. CONCLUSIONS: The overall midterm outcome of this series of 30 press-fit bipolar radial head arthroplasties can be considered favorable. Although the revision rate was 11%, the stems were well fixed in all. There was 1 (4%) additional radiologic failure. We suggest considering a press-fit bipolar radial head prosthesis for acute comminuted radial head fractures with limited bone loss of the proximal radius.

Biomechanical considerations in the pathogenesis of osteoarthritis of the elbow.

Osteoarthritis is the most common joint disease and a major cause of disability. Distinct biological processes are considered crucial for the development of osteoarthritis and are assumed to act in concert with additional risk factors to induce expression of the disease. In the classical weightbearing joints, one such risk factor is an unfavourable biomechanical environment about the joint. While the elbow has long been considered a non-weightbearing joint, it is now assumed that the tissues of the upper extremity may be stressed to similar levels as those of the lower limb, and that forces across the elbow are in fact very high when the joint is extended from a flexed position. This review examined the available basic science, preclinical and clinical evidence regarding the role of several unfavourable biomechanical conditions about the elbow on the development of osteoarthritis: post-traumatic changes, osteochondritis dissecans, instability or laxity and malalignment. Post-traumatic osteoarthritis following fractures is well recognized, however, the role of overload or repetitive microtrauma as risk factors for post-traumatic osteoarthritis is unclear. The natural course of untreated cartilage defects in general, and osteochondritis dissecans at the elbow in particular, remains incompletely understood to date. However, larger lesions and older age seem to be associated with more symptoms and radiographic changes in the long term. Instability seems to play a role, although the association between instability and osteoarthritis is not yet clearly defined. No data are available on the association of malalignment and osteoarthritis, but based on force estimations across the elbow joint, it seems reasonable to assume an association.

Distal humerus prosthetic hemiarthroplasty: midterm results.

Treatment of comminuted distal humeral fractures remains challenging. Open reduction-internal fixation remains the preferred treatment, but is not always feasible. In selected cases with non-reconstructable or highly comminuted fractures, total elbow arthroplasty has been used, however, also with relatively high complication and failure rates. Distal humerus prosthetic hemiarthroplasty (DHA) may be an alternative in these cases. The purpose of this study was to report the midterm results of six patients that were treated by DHA for acute and salvage treatment of non-reconstructable fractures of the distal humerus. All six patients were treated by DHA for acute and salvage treatment of non-reconstructable fractures of the distal humerus. Medical records were reviewed, and each patient was seen in the office. Mean follow-up was 54 months (range 21-76 months). Implant survival was 100 %. Three were pain free and three had mild or moderate residual pain. Average flexion-extension arc was 95.8° (range 70°-115°) and average pronation-supination arc was 165° (range 150°-180°). In three, there was some degree of instability, which was symptomatic in one. One had motoric and sensory sequelae of a partially recovered traumatic ulnar nerve lesion. According to the Mayo Elbow Performance Score, there were three excellent, one good and two poor results. Four were satisfied with the final result, and two were not. In this case series of six patients with DHA for non-reconstructable distal humerus fractures, favorable midterm follow-up results were seen; however, complications were also observed.

Radiocapitellar prosthetic arthroplasty: a report of 6 cases and review of the literature.

BACKGROUND: Radiocapitellar prosthetic arthroplasty has recently been introduced to treat isolated degenerative arthritis of the radiocapitellar joint. Although this procedure is conceptually attractive and sound in situations in which radial head resection is inadequate, clinical experience is still limited. Its role in the treatment of isolated radiocapitellar degenerative arthritis in the ligamentous-intact elbow and forearm is not yet defined. Our purpose was to report the short-term results of 6 patients who were treated by radiocapitellar prosthetic arthroplasty for isolated radiocapitellar degenerative arthritis in the ligamentous-intact elbow, as well as to provide a review of the literature. METHODS: Six patients were treated by radiocapitellar prosthetic arthroplasty for isolated degenerative arthritis of the radiocapitellar joint in the ligamentous-intact elbow. Their medical records were reviewed, and each patient was seen in the office. The mean follow-up period was 50 months (range, 30-64 months). RESULTS: The implant survival rate was 100%. Pain improved in all patients and all patients were satisfied. The mean flexion-extension arc increased from 98° (range, 75°-115°) to 110° (range, 105°-120°) (P = .17), and the mean pronation-supination arc increased from 133° (range, 75°-115°) to 143° (range, 120°-170°) (P = .34). The mean Disabilities of the Arm, Shoulder and Hand score was 24.3 (range, 6.7-52.5). According to the Mayo Elbow Performance Score, there were 3 excellent and 3 good results. CONCLUSION: The short-term follow-up results of radiocapitellar prosthetic arthroplasty for isolated radiocapitellar degenerative arthritis in the ligamentous-intact elbow and forearm seem favorable. LEVEL OF EVIDENCE: Level IV, case series, treatment study.

Biomechanical considerations in the pathogenesis of osteoarthritis of the knee.

Osteoarthritis is the most common joint disease and a major cause of disability. The knee is the large joint most affected. While chronological age is the single most important risk factor of osteoarthritis, the pathogenesis of knee osteoarthritis in the young patient is predominantly related to an unfavorable biomechanical environment at the joint. This results in mechanical demand that exceeds the ability of a joint to repair and maintain itself, predisposing the articular cartilage to premature degeneration. This review examines the available basic science, preclinical and clinical evidence regarding several such unfavorable biomechanical conditions about the knee: malalignment, loss of meniscal tissue, cartilage defects and joint instability or laxity. Level of evidence IV.

Are anidulafungin or voriconazole released from polymethylmethacrylate in vitro?

BACKGROUND: Depot delivery of antimicrobial agents is used for treatment and prevention of bacterial orthopaedic infections; there is little information regarding newer antifungal agents and their potential use in polymethylmethacrylate (PMMA) depot delivery. QUESTIONS/PURPOSES: We determined the percent of anidulafungin or voriconazole present after polymerization in PMMA beads loaded with anidulafungin or voriconazole, and we assessed elution of anidulafungin or voriconazole from beads loaded with anidulafungin or voriconazole. MATERIALS AND METHODS: Beads containing 7.5% anidulafungin or voriconazole were pulverized and incubated in Kreb's ringer buffer for 48 hours; the buffer was assayed for anidulafungin or voriconazole concentration. The in vitro release of anidulafungin and voriconazole from PMMA beads loaded with 7.5% anidulafungin or voriconazole was determined in triplicate in a continuous flow chamber. RESULTS: 0.7% of anidulafungin and 5.6% of voriconazole loaded in the beads were detected after polymerization. No anidulafungin was detected in the elution studies. The mean peak voriconazole concentration in the elution studies was 0.9 µg/mL. CONCLUSIONS: Anidulafungin may not be suitable for depot delivery in PMMA.

Delayed treatment of elbow pain and dysfunction following Essex-Lopresti injury with metallic radial head replacement: a case series.

BACKGROUND: Chronic longitudinal radioulnar dissociation has been associated with unpredictable and generally unfavorable outcomes. Metallic radial head replacement may address this treatment deficiency. METHODS: Eight patients were treated with a metallic radial head replacement for chronic longitudinal radioulnar dissociation. The average treatment delay was 3.3 years. All eight patients were seen for a clinical and radiographic assessment. RESULTS: Five of the 8 failed after a mean of 3 years (range, 1-5.7). Revision to bipolar metallic radial head replacement was successful in the short term in 2 of 3 that failed from aseptic loosening. One of 2 failures due to painful radiocapitellar arthritis was salvaged with a capitellar replacement. DISCUSSION: Reconstruction for symptoms following an Essex-Lopresti injury remains problematic. A metallic radial head implant appears to be an effective adjunct, but not a perfect solution in all patients. Recognition of the negative impact of residual lateral ulnar collateral ligament laxity is an important observation and should be specifically addressed with the reconstructive procedure. CONCLUSION: Metallic monoblock radial head replacement did not reliably address the functional deficiency from chronic radioulnar dissociation primarily due to malalignment and implant loosening. A cemented bipolar radial head implant may provide a better alternative as a long-term solution. Regardless, ligamentous integrity at the elbow should also be addressed at the time of the reconstruction.

Enhanced bone morphogenetic protein-2-induced ectopic and orthotopic bone formation by intermittent parathyroid hormone (1-34) administration.

Bone morphogenetic proteins (BMPs) play a central role in local bone regeneration strategies, whereas the anabolic features of parathyroid hormone (PTH) are particularly appealing for the systemic treatment of generalized bone loss. The aim of the current study was to investigate whether local BMP-2-induced bone regeneration could be enhanced by systemic administration of PTH (1-34). Empty or BMP-2-loaded poly(lactic-co glycolic acid)/poly(propylene fumarate)/gelatin composites were implanted subcutaneously and in femoral defects in rats (n = 9). For the orthotopic site, empty defects were also tested. Each of the conditions was investigated in combination with daily administered subcutaneous PTH (1-34) injections in the neck. After 8 weeks of implantation, bone mineral density (BMD) and bone volume were analyzed using microcomputed tomography and histology. Ectopic bone formation and almost complete healing of the femoral defect were only seen in rats that received BMP-2-loaded composites. Additional treatment of the rats with PTH (1-34) resulted in significantly (p < 0.05) enhanced BMD and bone volume in the BMP-2 composites at both implantation sites. Despite its effect on BMD in the humerus and vertebra, PTH (1-34) treatment had no significant effect on BMD and bone volume in the empty femoral defects and the ectopically or orthotopically implanted empty composites. Histological analysis showed that the newly formed bone had a normal woven and trabecular appearance. Overall, this study suggests that intermittent administration of a low PTH dose alone has limited potential to enhance local bone regeneration in a critical-sized defect in rats. However, when combined with local BMP-2-releasing scaffolds, PTH administration significantly enhanced osteogenesis in both ectopic and orthotopic sites.

Effect of local sequential VEGF and BMP-2 delivery on ectopic and orthotopic bone regeneration.

Bone regeneration is a coordinated cascade of events regulated by several cytokines and growth factors. Angiogenic growth factors are predominantly expressed during the early phases for re-establishment of the vascularity, whereas osteogenic growth factors are continuously expressed during bone formation and remodeling. Since vascular endothelial growth factor (VEGF) and bone morphogenetic proteins (BMPs) are key regulators of angiogenesis and osteogenesis during bone regeneration, the aim of this study was to investigate if their sequential release could enhance BMP-2-induced bone formation. A composite consisting of poly(lactic-co-glycolic acid) microspheres loaded with BMP-2 embedded in a poly(propylene) scaffold surrounded by a gelatin hydrogel loaded with VEGF was used for the sequential release of the growth factors. Empty composites or composites loaded with VEGF and/or BMP-2 were implanted ectopically and orthotopically in Sprague-Dawley rats (n=9). Following implantation, the local release profiles were determined by measuring the activity of (125)I-labeled growth factors using scintillation probes. After 8 weeks blood vessel and bone formation were analyzed using microangiography, microCT and histology. The scaffolds exhibited a large initial burst release of VEGF within the first 3 days and a sustained release of BMP-2 over the full 56-day implantation period. Although VEGF did not induce bone formation, it did increase the formation of the supportive vascular network (p=0.03) in ectopic implants. In combination with local sustained BMP-2 release, VEGF significantly enhanced ectopic bone formation compared to BMP-2 alone (p=0.008). In the orthotopic defects, no effect of VEGF on vascularisation was found, nor was bone formation higher by the combination of growth factors, compared to BMP-2 alone. This study demonstrates that a sequential angiogenic and osteogenic growth factor release may be beneficial for the enhancement of bone regeneration.

Non-invasive monitoring of BMP-2 retention and bone formation in composites for bone tissue engineering using SPECT/CT and scintillation probes.

Non-invasive imaging can provide essential information for the optimization of new drug delivery-based bone regeneration strategies to repair damaged or impaired bone tissue. This study investigates the applicability of nuclear medicine and radiological techniques to monitor growth factor retention profiles and subsequent effects on bone formation. Recombinant human bone morphogenetic protein-2 (BMP-2, 6.5 microg/scaffold) was incorporated into a sustained release vehicle consisting of poly(lactic-co-glycolic acid) microspheres embedded in a poly(propylene fumarate) scaffold surrounded by a gelatin hydrogel and implanted subcutaneously and in 5-mm segmental femoral defects in 9 rats for a period of 56 days. To determine the pharmacokinetic profile, BMP-2 was radiolabeled with (125)I and the local retention of (125)I-BMP-2 was measured by single photon emission computed tomography (SPECT), scintillation probes and ex vivo scintillation analysis. Bone formation was monitored by micro-computed tomography (microCT). The scaffolds released BMP-2 in a sustained fashion over the 56-day implantation period. A good correlation between the SPECT and scintillation probe measurements was found and there were no significant differences between the non-invasive and ex-vivo counting method after 8 weeks of follow up. SPECT analysis of the total body and thyroid counts showed a limited accumulation of (125)I within the body. Ectopic bone formation was induced in the scaffolds and the femur defects healed completely. In vivo microCT imaging detected the first signs of bone formation at days 14 and 28 for the orthotopic and ectopic implants, respectively, and provided a detailed profile of the bone formation rate. Overall, this study clearly demonstrates the benefit of applying non-invasive techniques in drug delivery-based bone regeneration strategies by providing detailed and reliable profiles of the growth factor retention and bone formation at different implantation sites in a limited number of animals.

Self-assembled monolayer films of phosphonates for bonding RGD to titanium.

Modification of the implant surface with the Arg-Gly-Asp tripeptide (RGD) putatively facilitates osteoblast attachment for improved implant fixation in the laboratory. We compared the histomorphometric and mechanical performance of titanium implants coated with RGD using a novel interface of self-assembled monolayers of phosphonates (RGD/SAMP) and implants coated with RGD using the more conventional thiolate-gold interface (RGD/thiolate-gold). We hypothesized RGD/SAMP-coated implants would show greater bone ongrowth and implant fixation than RGD/thiolate-gold-coated ones. We implanted an RGD/SAMP-coated implant in one femur and an RGD/thiolate-gold-coated in the contralateral femur of 60 rats. At 2, 4, and 8 weeks after implantation, 10 rats were sacrificed for histologic evaluation and another 10 for biomechanical testing. Bone-implant ongrowth and implant force-to-failure of the two implants were similar at all times. Although RGD/SAMP-coated implants did not show superior bone ongrowth and implant fixation, RGD/SAMP-coated implants have at least equally good histomorphometric and mechanical in vivo performance as RGD/thiolate-gold-coated ones. Additional in vivo characterization of self-assembled monolayer films of phosphonates as interface to bond RGD to titanium is needed to explore its full potential and seems justified based on the results of this study.

Successful canine patellar tendon reattachment to porous tantalum.

The ability to achieve reattachment of soft tissues, such as tendon, directly onto a prosthetic surface would be of great benefit in case of periarticular bone loss or resection. Bone and potential soft tissue ingrowth using porous tantalum has been observed in prior animal studies. We hypothesized porous tantalum washers used to reattach canine patellar tendon to bone would provide sufficient strength to withstand physiologic loading. We reattached the released patellar tendon to the tibia using two porous tantalum washers in 33 skeletally mature dogs. Force plate analysis of gait, tensile testing of the tendon reconstruction, and histologic analysis of tissue ingrowth into the implants were performed after 3, 6, and 12 weeks' survival. Physiologic weightbearing on the operated leg had normalized 6 weeks after tendon reconstruction surgery. The mechanical strength of the tendon reattachment was 76% of the strength of the native tendon insertion by 6 weeks but did not increase further with time. Fibrous tissue occupied approximately 1/2 of the available space in the porous tantalum washers at all times. Our data suggest tendon healing into a prosthetic material can be achieved using porous tantalum washers with sufficient mechanical strength to withstand physiologic loading.

Local antibiotic delivery with OsteoSet, DBX, and Collagraft.

Biodegradable local antibiotic delivery systems have gained interest for prophylaxis and treatment of musculoskeletal infections. We studied the biodegradable materials Osteo- Set, DBX and Collagraft for local delivery of vancomycin and gentamicin in vitro. We determined the antimicrobial activity of vancomycin and gentamicin after mixing with each biodegradable material and determined the release of each antimicrobial from each material in an intermittent flow chamber. Antimicrobial activity was expressed as percent of antimicrobial loaded into each sample that was detected; antimicrobial release was expressed as concentration (microg/mL) after timed intervals of chamber flow, peak concentration, area under the curve and percent antimicrobial recovered. Activity of vancomycin after mixing with Osteo- Set, DBX and Collagraft was > 73%. Activity of gentamicin after mixing with DBX was 100%; after mixing with OsteoSet and Collagraft it was reduced to < 61%. AUC0-48hrs of vancomycin was 469, 426 and 432 microg x hr/mL, and the AUC0-48hrs of gentamicin was 368, 306 and 301 microg x hr/mL after release from OsteoSet, DBX, and Collagraft, respectively. Recovered percentages of vancomycin were 39%, 11% and 25%, and recovered percentages of gentamicin were 39%, 9% and 23% after release from OsteoSet, DBX, and Collagraft, respectively. OsteoSet, DBX and Collagraft may be suitable for local delivery of vancomycin and gentamicin.