Vancomycin-laden calcium phosphate-calcium sulfate composite allows bone formation in a rat infection model.

OBJECTIVE: Local antibiotic delivery systems with differing chemical and mechanical properties have been developed to assist in the management of osteomyelitis. We investigated the bone conductive and resorptive capabilities of a calcium phosphate-calcium sulfate (CaP/CaS) composite compared with commercially available polymethylmethacrylate (PMMA). In addition, we compared the in vivo preventative and treatment efficacies of both biomaterials in a proven osteomyelitis model. METHODS: Sixty-four, male Sprague-Dawley rats were inoculated with 10 µl of 1.5 x 108 CFU/ml of Staphylococcus aureus in a surgically drilled defect in the right proximal tibia. Infected animals were randomly allocated into prevention and treatment groups with 32 rats each. In the prevention group, the defect was filled with a plug containing either PMMA or CaP/CaS immediately after the inoculation. In the treatment group, the infected defects were irrigated, debrided, and filled with either a PMMA or CaP/CaS plug. Both CaP/CaS and PMMA were impregnated with 10% weight of vancomycin. Rats were sacrificed 6 weeks after cement insertion. Infection was detected by bacterial culture and histological analysis. Bone formation in the defect was assessed with micro-computed tomography and histology. RESULTS: No bacteria were detected in any group. Both the prevention and treatment groups using CaP/CaS had significantly more bone volume fraction, bone area, and cartilage area than the PMMA groups. CONCLUSIONS: When loaded with 10% of vancomycin, CaP/CaS and PMMA have the same efficacy for treatment and prevention of osteomyelitis. CaP/CaS enhances bone defect healing through improved bone remodeling in our osteomyelitis rat model.

Stem Cell Interventions for Bone Healing: Fractures and Osteoporosis.

With the ageing population, musculoskeletal conditions are becoming more inherent. Delayed union is defined as a slower than normal fracture healing response, with no healing after 4 to 6 months; however, the union is anticipated given sufficient time. In the context of delayed/non-union, fragility fractures in osteoporotic populations carry significant patient morbidity and socioeconomic costs. Multiple mechanisms hinder fracture healing in osteoporotic patients, imbalanced bone remodelling leads to impaired bone microarchitecture due to reduced osteoblast number and activity and as such, callus formation is diminished. Since stem cells can self-renew and differentiate into various tissue lineages, they are becoming very popular in tissue regeneration in musculoskeletal conditions. In this review, we discuss the role of stem cells in physiological fracture healing and their potential therapeutic use following a fracture. We explore the potential of stem cells, the release of chemokines and cytokines to reduce fracture risk in osteoporosis.

Advances in 3D Modeling: Preoperative Templating for Revision Wrist Surgery.

BACKGROUND: Three-dimensional (3D) printing is a computer-directed process leading to the layered synthesis of scaled models. The popularity and availability of the technique has exponentially increased over the last decade, and as such is seeing a greater number of medical and surgical applications. METHODS: We report 3 cases involving the use of 3D printing as an aid to operative planning in the revision of wrist surgery. RESULTS: All patients underwent successful operative interventions with a £34 average cost of model creation. CONCLUSIONS: A growing number of reports are emerging in reconstructive surgical specialities including maxillofacial, orthopedic, and plastic surgery; from our experience, we advocate the economically viable use of 3D printing for preoperative templating.

Patient-Reported Outcomes Following Surgically Managed Perilunate Dislocation: Outcomes After Perilunate Dislocation.

BACKGROUND: Perilunate dislocations (PLDs) are uncommon high-energy injuries that may result in significant morbidity if inadequately treated. We report the midterm outcomes following surgical intervention and the validity of the Patient-Rated Wrist Evaluation (PRWE) score as an assessment tool post injury. METHODS: We prospectively present outcomes in 16 patients with perilunate injuries. Definitive surgical management comprised fixation of all fractures and anatomical reconstruction of ruptured ligaments where possible. All patients completed the Disabilities of the Arm, Shoulder and Hand (DASH), 12-Item Short-Form Health Survey, and PRWE, for which internal consistency and construct validity were assessed. RESULTS: At 24 months, the mean grip strength was 59% of the uninjured side (range 33%-85%) and the mean range of flexion was 71% and extension was 58%. Eighty-eight percent of patients returned to work within 6 months and 63% to sport within 1 year. The PRWE score was 36.2 (range 14.5-77.3) and DASH 25.2 (range 7.5-91.7). The mean visual analog scale (VAS) satisfaction score was 7.9 (range 0-10), VAS pain at rest 1.9 (range 0-6) and on activity 3.3 (range 1-6). DASH and PRWE demonstrated similar internal consistencies with Cronbach alphas of .98 and .91, respectively, and a strongly positive correlation coefficient of r = +.7 (P < .05). CONCLUSIONS: Surgical treatment of PLDs can provide good clinical outcomes allowing patients to return to normal activities in a reasonable timescale when delays to surgery are kept to a minimum. The PRWE demonstrated high internal consistency and was found to be a valid questionnaire with advantages over the DASH for use following severe carpal injures.

Intraosseous ganglion cysts of the carpus: current practice.

Intraosseous cysts of the carpal bones are an infrequent cause of chronic wrist pain. The main body of work has investigated their occurrence in the proximal carpus, with limited incidence in the distal row. We review the current literature on the treatment of symptomatic carpal cysts following the report of a 17-year-old male with a 12-month history of progressive right wrist pain due to an intraosseous ganglion of the trapezoid. This review explores the pathology of carpal cysts, their varying presentation and current treatments.

Profunda femoris injury following lesser trochanter displacement: complications following intramedullary femoral nailing.

Iatrogenic vascular complications following intramedullary nailing of hip fractures is a rare occurrence. We describe a case report of injury to the profunda femoris artery due to a displaced lesser trochanteric fragment following ambulation. We discuss the mechanism of arterial injury and associated signs in addition to possible preventative strategies.

Custom total hip arthroplasty in skeletal dysplasia.

PURPOSE: Osteochondrodysplasias are characterised by aberrant cartilage and bone development; consequently, patients may be subject to premature hip degeneration. In this population hip arthroplasty outcomes are variable. This series reviews the use of custom femoral implants in total hip replacements for patients with severe skeletal dysplasia. METHODS: We reviewed 14 hips in nine patients with genetic dwarfism. Computed tomography (CT) scans of the pelvis and femurs were used to create custom titanium stems. Postoperative radiographs were reviewed for migration, osteolysis, fracture and restoration of leg length. Pre- and postoperative Harris hip scores (HHS) were compared, with a mean follow-up of 36.3 months. Mean age was 36.5 years (range 15-50 years) and mean height was 48 inches (range 42-55 inches). Three joints were classified as Crowe type I, two type II, three type III and six type IV. RESULTS: Three hips (21%) required revision: two for stem migration and one for acetabular osteolysis. Eleven hips (79%) were stable with signs of osseointegration. No fractures, nerve damage or dislocations occurred. Two stems required cement fixation, and no liners were constrained. Significant osteolysis was seen on three radiographs. All patients walked independently, and mean HHS improved from 45 (24-58) to 71 (47-89). All leg length discrepancies were restored to within 3 mm of equal. CONCLUSIONS: This study reports good midterm outcomes in a variety of skeletal dysplasias, thus confirming the efficacy of custom femoral implants in the management of this patient group.

In vitro elution characteristics of vancomycin in a composite calcium phosphate/calcium sulfate bone substitute.

BACKGROUND: Periprosthetic joint infection is a particularly difficult orthopedic problem, complicating a growing number of revision procedures. Joint debridement and systemic antibiotics are the mainstay of treatment, yet difficulty remains in maintaining a minimum inhibitory concentration of antibiotic at the localized site of infection. STUDY AIMS: This study analyzes the elution characteristics of a 40%bwt calcium phosphate-60%bwt calcium sulfate composite, at varying concentrations of vancomycin. METHODS: Four groups of varying concentrations of vancomycin (2.63%bwt, 5.13%, 9.76%, and 17.78%) were mixed with one pack of the composite cement. At designated time intervals up to 28 days, the antibiotic concentration was detected using fluorescence polarization immunoassay and the elution trends compared. RESULTS: The elution rate of each of the four groups decreased over time. At almost all of the intervals, the elution rates of the higher concentration groups were significantly higher than the lower concentration groups (P < 0.05). CONCLUSIONS: Calcium sulfate reabsorbs over a prolonged period, producing porosity which allows for new bone ingrowth through occupation of osteoprogenitor cells and osteoblasts; while calcium phosphate acts as a long-term osteoconductive matrix. CLINICAL RELEVANCE: The results of this study suggest that vancomycin can be mixed affectively with a calcium sulfate/phosphate composite, both maintaining stability and eluting gradually over a clinically relevant period of time.

A custom coupling device of total knee and ipsilateral total hip arthroplasties after distal femoral fracture.

The treatment of periprosthetic femoral fractures around long-stemmed hip implants is an orthopedic challenge, which may be complicated by the presence or need for a total knee arthroplasty. Treatment of this fracture when the proximal implant is well fixed and a distal implant is required poses ongoing challenges. Traditional plating and allograft struts have produced variable results, particularly in osteoporotic bone, where incidence of nonunion is greater. Thus, we report a custom interlocking device, which couples the stem of the fixed proximal implant to a new stemmed total knee prosthesis, resulting in the expedited restoration of functionality and fracture union.

The lack of correlation between radiographic findings and cartilage integrity.

Total knee arthroplasty is a common treatment of osteoarthritis, although unicompartmental knee arthroplasties are frequently used to retain unaffected compartments. Joint space width (JSW) is a major factor in determining treatment. We examined the relationship between JSW and cartilage quality in 60 patients undergoing total knee arthroplasty to assess its accuracy in representing cartilage degradation. Radiographic JSW was recorded, whereas the unaffected compartment of each tibial plateau was examined postoperatively using Collins, Mankin, and Kellgren and Lawrence scores. No correlation was seen between visual or histologic grading and JSW. Histology more accurately represented cartilage quality, yet it is impractical to obtain preoperatively; thus, JSW is the main mode of assessment. However, using JSW solely to indicate unicompartmental knee arthroplasty may overlook disease in apparently unaffected compartments.