A patient in his thirties developed synovitis with grade 4 chondrolysis and a stiff knee with a fixed flexion deformity between three and six years following PLC and PCL reconstruction using LARS (Ligament Augmentation and Reconstruction System, Corin). There was histologic evidence of foreign body reaction, the knee was painful, swollen and stiff. We did not use any further LARS ligaments for soft tissue reconstructions of the kneein our practice. We commenced a recall programme for all 83 patients patients who underwent a soft tissue knee reconstruction using LARS. Of those contacted, 41 replied (49%) and 16 patients had symptoms (19%) and were investigated further with XRay, MRI and arthroscopy as indicated. We discovered a total of five patients had histologically proven synovitis with foreign body reactions (6%), three of whom had life-changing symptomatic pain, swelling and stiffness with degenerate changes (3.6%). These patients had undergone various reconstructions, including a) PLC only, b) ACL and PCL, c) PCL and PLC and d) ACL, PCL and PLC. A further single case of massive bone cyst formation was noted, following PCL reconstruction using LARS (1.2%)

Millions of medical devices made of synthetic or modified natural materials all trigger a similar reaction—the foreign body reaction. Biocompatibility, for materials that pass routine cytoxicity assays, is largely associated with a mild foreign body reaction. I.e. a thin, avacular, collagenous, non-adherent foreign body capsule. The implant is incorporated into a dead-zone of acellular scar. The contemporary tissue engineering paradigm would suggest that synthetic polymers and scaffolds lacking cellular, biomolecule or biomimetic elements will give this same fibrotic, avascular healing reaction. In this talk, a synthetic biomaterial will be described that readily integrates into tissue and may stimulate spontaneous reconstruction of tissue. The material is fabricated by a process called sphere-templating and it can be made from many synthetic polymers including hydrogels, silicones and polyurethanes. All pores are identical in size and interconnected. Studies from our group have shown optimal healing (as suggested by extensive vascularity and minimal fibrosis) for spherical pores of 30–40 m size. The integrative healing noted is independent of biomaterial. Similar results are observed with sphere-templated silicone rubber and pHEMA hydrogel. In addition, surface chemical modification of the hydrogel with carbonyl diimidazole, or immobilisation on the hydrogel of collagen I or laminin did not change the healing response. Also, good healing results have been seen upon implantation in skin (subcutaneous, percutaneous), heart muscle, sclera, skeletal muscle, bone and vaginal wall. We consistently find the pore spaces heavily populated by monocytic cells that stain for macrophage cell surface markers. However, at long implantation times (16 or more weeks), the ability to stain for macrophage surface markers decreases. It could be possible that these cells populating the implants are differentiating into other tissues. Thus, such materials may represent a path to cell-free tissue engineering. Others have seen similar healing results, via completely different materials strategies, generally involving biological molecules. The in vivo results from our group and related results from other groups suggest we are on the cusp of a revolution in healing, biomaterials integration and tissue reconstruction. Also, the boundaries between biomaterials and tissue engineering continue to blur

[Introduction]. In 1995, Muller reported on the improvement of metal-on-metal (MOM) bearing over the existing metal-on-polyethylene (MOP) articulations which demonstrated more rapid wear together with granulomatous foreign body reactions, damage of periarticular bony and soft tissues and associated expansile psoas bursal masses. He suggested that adequate lubrication together with improved material properties and manufacturing technologies would bring to the market a superior device with greater longevity. We wish to present our experience with a modern version of a MOM bearing. [Material and Methods]. Between April 2008 and February 2012, we implanted 160 MOM THA with head diameters of 38–50 mm in 139 patients (21 males and 118 females). Their ages were 40–86 years (avg. 63.6 yrs). Follow up was 9 to 53 months post implantation (avg. 28 months). All implants were manufactured by one company (Wright Medical Technology, Arlington, TN, USA). The stems were of a standard titanium-aluminum alloy, either 45 ANCA-FIT or 115 PROFEMUR Z non-cemented stems. Acetabular components were all CONSERVE PLUS cobalt-chromium monoblock shells. Heads were also fabricated out of cobalt-chromium alloy, with modular junctions. Patients with complaints of groin pain and/or swelling or hip instability underwent MRI examination in order to detect the presence of fluid collections or soft tissue masses (Fig. 1 and 2). The statistical correlation between abnormal findings on MRI and age, gender, head diameter, component position and duration post-surgery was performed. [Results]. 27 hips in 23 patients (16.9%) were found to have either a fluid collection or “pseudotumor”. These were in 2 males and 21 female patients. There were 19 males and 97 females without complaints who did not undergo MRI examination. There was no difference in age between these two groups of patients (63.1 vs. 63.7 yrs). There was no difference in duration from the time of implantation, but there was an early presentation of symptomatic pseudotumor. There appeared to be a significant difference between the mean head diameter of the two groups, 41.8 mm and 44.2 mm respectively. There was no statistical difference between the two groups with regard to implant orientation: cup inclination 18–70 degrees (40.4 vs. 43.8 degrees); cup anteversion −13−49 degrees (14.0 vs. 15.0 degrees); stem anteversion 2–48 degrees (20.2 vs. 23.1 degrees); and stem offset 17.5–56.2 mm (38.2 vs. 37.8 mm). [Discussion]. In this study, it is important to emphasize that the appearance of symptoms and development of a pseudotumor occurred early after a MOM THA in some patients. It may represent a hypersensitivity to materials implanted. However, the possibility that this may represent a foreign body reaction to particulate debris produced by articulating surfaces much like that seen with alternative material such as MOP, reflective of wear, insufficient lubrication or other causes. In this regard, our study suffers from the limitation that serum levels of chromium and cobalt were not obtained from symptomatic patients. Nor were these patients skin tested for hypersensitivity to these materials. Also it will be important to subject all patients to MRI examination to evaluate the possibility of “silent” fluid collections and pseudotumors

Innominate Osteotomy first described by Salter is one of the commonest procedures performed for treatment of Developmental Dysplasia of the Hip (DDH) in children. We recently described a less invasive technique for Innominate Osteotomy, which significantly reduces the operation time without compromising outcome (J Pediatr Orthop B. 2010 Jul;19(4):318–22). As part of the evolution of this procedure we now routinely use bioabsorbable pins (INION OTPS PIN, made from co-polymers of L-lactic acid, D-lactic acid and trimethylene carbonate) instead of K-wires to secure the graft. We prospectively followed-up 120 consecutive cases done using bioabsorbale pins over a 2 year period. The surgical technique was as described in our less invasive innominate osteotomy paper. Average age at surgery was 24 months (18–52) with mean follow-up period of 15 months (6–24 months). The mean preoperative acetabular index was 36.2. o. Our results show a mean acetabular index of 18.7. o. (P< 0.0001) at latest follow-up with no loss of correction. We recorded three superficial wound infections (one MRSA), all resolved uneventfully. There was no foreign body reaction. The use of bioabsorbable pins eliminates the need for a second anaesthetic to remove the pins with significant cost benefit without compromising outcome

Cobalt-chrome alloys are widely used in dentistry and Orthopaedic implant industry. Vitallium is a similar alloy which contains 60% cobalt, 20% chromium, 5% molybdenum along with traces of other substances. It has been in use along with stainless steel for the last century because of its lightweight, favourable mechanical properties and resistance to corrosion. We present an unusual case of synovial cyst formation following Vitallium plating mimicking a sarcoma. To our knowledge, we are the first to report a delayed tissue reaction to Vitallium plating 40 years after its implantation. A 78 yrs old man had a right femoral intertrochanteric fracture 40 years ago, which was fixed with a Vitallium nail plate. His postoperative recovery was uneventful and he regained full function of his leg. 3 years prior to excision, he presented with a painless swelling around his right upper thigh to our unit. Aspiration of the swelling and investigations were requested but patient was lost to follow up due to social reasons. Seven months prior to excision, he represented as the swelling had increased to the extent that it was involving the anterior and posterior aspect of the upper thigh with pressure necrosis of skin posteriorly. Examination revealed painless, transilluminable, fluctuant multilobular swelling over the right proximal femur overlying the healed surgical scar. Compression of the larger lobe in the buttock clearly forced fluid into the anterior compartment of the thigh where again swelling was extensive. Surprisingly he had full range of movements at the hip joint. Radiograph of the hip showed a soft tissue swelling with a healed fracture and Vitallium implant insitu. Cytology was negative. MRI scan showed multiloculated cystic lesions extending anteriorly, laterally and posteriorly into the intermuscular and subcutaneous planes around the right proximal femur. Multiple small dependent foci likely representing debris or synovial proliferation was seen within loculations. Excision of the cystic lesions with removal of metal work was performed. The old incision was reopened in the lateral position and a large cystic lesion with a thick capsule was dissected down to the metal work. The lesion was lying superficial to the vastus lateralis but was communicating with metal work. The metal work was removed with difficulty, no visible metallosis. A second cystic lesion was located more posteriorly but its neck was communicating with the thin hole into the first lesion. The lesion was excised completely. Macroscopic examination showed two cysts 9×8×5.5cm and 20×10×7.5cm with a smooth external surface and the lumen appeared trabecular containing numerous loose (rice) bodies. Microscopy showed a dense fibrotic cyst wall with lumen with multiple small nodules containing organised fibrinous and eosinophilic material. Several foci of cellular debris including lymphocytes and macrophages were scattered in nodules best representing a synovial cyst with loose/rice bodies. No malignancy was seen. We recommend early removal of metal work if it shows any signs of local reaction provided fracture is united. Be aware of large foreign body/ hypersensitivity reaction and incompatible equipment for removal

The number of arthroplasties being undertaken is expected to grow year on year, and periprosthetic joint infections will be an increasing socioeconomic burden. The challenge to prevent and eradicate these infections has resulted in the emergence of several new strategies, which are discussed in this review.

Cite this article: Bone Joint J 2015;97-B:1162–9.