Effect of Casting Material on the Cast Pressure After Sequential Cast Splitting.

BACKGROUND: Circumferential casting is a vital component of nonoperative fracture management. These casts are commonly valved to release pressure and decrease the risk of complications from swelling. However, little information exists regarding the effect of different casting supplies on the pressure within the cast. METHODS: Seventy-five long-arm casts were performed on human volunteers, divided between 5 experimental groups with 15 casts in each groups. Testing groups consisted of 2 groups with a plaster short-arm cast overwrapped with fiberglass to a long arm with either cotton or synthetic cast padding. The 3 remaining groups included fiberglass long-arm casts with cotton, synthetic, or waterproof cast padding. A pediatric blood pressure cuff bladder was placed within the cast and inflated to 100 mm Hg. After inflation, the cast was sequentially released with pressure reading preformed after each stage. Order of release consisted of cast bivalve, cast padding release, and cotton stockinet release. After release, the cast was overwrapped with a loose elastic bandage. Difference in pressure readings were compared based upon the cast material. RESULTS: Pressures within the cast were found to decrease with sequential release of cast. The cast type had no effect of change in pressure. Post hoc testing demonstrated that the type of cast padding significantly affected the cast pressures with waterproof padding demonstrating the highest pressure readings at all time-points in the study, followed by synthetic padding. Cotton padding had the lowest pressure readings at all time-points. DISCUSSION: Type of cast padding significantly influences the amount of pressure within a long-arm cast, even after bivalving the cast and cutting the cast padding. Cotton cast padding allows for the greatest change in pressure. CLINICAL RELEVANCE: Cotton padding demonstrates the greatest change in pressure within a long-arm cast after undergoing bivalve. Synthetic and waterproof cast padding should not be used in the setting of an acute fracture to accommodate swelling.

Volumetric Considerations for Valving Long-Arm Casts: The Utility of the Cast Spacer.

Fiberglass casts are frequently valved to accommodate swelling following injury or surgery. The use of cast spacers has been recommended to bridge this gap between pressure reduction and cast strength, but no studies have assessed their effect on cast pressure. We applied 30 long-arm fiberglass casts to adult volunteers, divided between a univalve group and a bivalve group. A pediatric blood pressure bladder was applied under the cast to simulate soft tissue swelling. Valved casts were secured using an elastic wrap, 10-mm cast spacer, or 15-mm cast spacer. Measurements of cast pressure and circumference were performed at each stage and compared on the basis of type of valve and securement. Our results indicated that cast univalving resulted in an approximately 60% reduction in cast pressures, with a 75% reduction seen in the bivalve group. The addition of cast spacers resulted in significant pressure reductions for both valving groups. The univalve group secured with a 10-mm cast spacer produced reductions in cast pressure similar to those of the elastic-wrapped bivalve cast, both with the cast padding intact and with it released. The use of cast spacers results in significant cast pressure reductions, regardless of valving technique. A univalved cast secured with a cast spacer can produce decreases in cast pressures similar to those seen with an elastic-wrapped bivalved cast, and it is a viable option for reducing cast pressure without compromising cast structural integrity with a bivalve technique.

Improved Chondrotoxic Profile of Liposomal Bupivacaine Compared With Standard Bupivacaine After Intra-articular Infiltration in a Porcine Model.

BACKGROUND: Increasingly, liposomal bupivacaine is being used with multimodal pain management strategies. In vitro investigations have shown decreased chondrotoxicity profiles for liposomal bupivacaine; however, there is no evidence regarding its in vivo effects. Hypothesis/Purpose: This study sought to investigate the in vivo chondrotoxicity of liposomal bupivacaine, hypothesizing that there would be increased chondrocyte viability after exposure to liposomal bupivacaine when compared with standard bupivacaine. STUDY DESIGN: Controlled laboratory study. METHODS: Eight juvenile, female Yorkshire cross piglets underwent a lateral stifle joint injection with either 1.3% liposomal bupivacaine or 0.5% bupivacaine. Injections were performed on one joint per animal with no injection to the contralateral knee, which served as the control. Chondrocyte viability was assessed 1 week after injection with a live-dead staining protocol and histologic examination. RESULTS: Significant chondrocyte death was seen with the live-dead staining in the bupivacaine group (33% nonviable cells) in comparison with liposomal bupivacaine (6.2%) and control (5.8%) groups ( P < .01). However, histologic examination showed no differences in chondral surface integrity, fibrillation, and chondrocyte viability. CONCLUSION: Liposomal bupivacaine was found to be safe for intra-articular injection in this animal model. Although bupivacaine demonstrated decreased chondrocyte viability on a cellular level, histologically there were no changes. This study highlights the dichotomy between fluorescent staining and histologic appearance of articular chondrocytes in short-term analyses of viability. CLINICAL RELEVANCE: This study supports the peri-articular application of liposomal bupivacaine in the setting of preserved articular cartilage. A single injection of standard bupivacaine did not produce histologic changes in the articular cartilage.

Chondrotoxicity of Liposomal Bupivacaine in Articular Chondrocytes: Preliminary Findings.

OBJECTIVE: The chondrotoxicity of local anesthetics has been previously recognized. Recent introduction of a liposomal formulation of bupivacaine has been found to significantly improve postoperative pain control but its effect on chondrocyte viability has yet to be investigated with this new formulation. We sought to assess the in vitro chondrotoxicity of liposomal bupivacaine. METHODS: Chondrocytes were isolated from articular cartilage from fresh stifle joints and grown in culture medium. Cultured chondrocyte-derived cells (CDCs) were treated with 0.9% normal saline solution, 0.5%, 0.25%, and 0.13% bupivacaine and ropivacaine, 1.3% liposomal bupivacaine for 1 hour. Following treatment, cells were washed and incubated in media for 23 hours. The CDCs were then harvested and viability was assessed by flow cytometry using SYTOX green dead cell stain. RESULTS: Treated CDCs demonstrated a dose-response effect for chondrocyte viability when treated with bupivacaine, ropivacaine, and liposomal bupivacaine. Liposomal bupivacaine demonstrated the highest chondrocyte viability following treatment. Ropivacaine demonstrated higher chondrocyte viability than bupivacaine. CONCLUSION: Following 1 hour of treatment, liposomal bupivacaine demonstrated the highest chondrocyte viability. Chondrocyte viability was inversely proportional to anesthetic concentration.

Chondrocyte Viability After a Simulated Blast Exposure.

OBJECTIVES: The effects of blast exposure have gained increasing interest in the military medical community with their continued occurrence on the battlefield. The impact of the direct and indirect energy imparted from blasts to hollow viscera, as well as closed head injuries, have been well studied. However, the injury to articular cartilage has not been investigated, despite previous correlations regarding the development of osteoarthritis. The purpose of this study was to assess the degree of injury to articular chondrocytes after exposure to a simulated blast overpressure wave. METHODS: Fresh juvenile porcine stifle joints were subjected to a simulated blast overpressure wave utilizing a custom fabricated blast simulator with compressed gases, within the reported range of observed battlefield blasts. Chondrocyte viability was assessed with live/dead staining using ethidium homodimer-2 and calcien acetoxymethylester stain and confocal laser scanning microscopy, calculated as a ratio of dead chondrocytes to live chondrocytes. Testing was performed at time points of 2, 4, and 8 hours after blast exposure and was compared with unblasted control samples. RESULTS: Chondrocyte viability decreased after exposure to a blast overpressure wave when compared with control samples. The amount of death was greater closer to the articular surface and dissipated with increasing tissue depth. Chondrocyte death increased with time after exposure. CONCLUSIONS: Chondrocyte death is present after exposure to a simulated blast wave. There is an inverse relationship between chondrocyte viability and the depth from the articular surface. Additional studies are needed to further characterize dose and time effects of blast exposure.

Coccidioidal osteomyelitis of the patella.

Known as "Valley Fever," coccidiomycosis is a soil-borne, fungal infection predominately found in endemic regions of the southwestern United States and Latin America. While most infected individuals are asymptomatic, <1% of patients have hematogenous seeding of bone, skin, and soft tissue. When the musculoskeletal system is involved, the knee is most commonly affected, although infection has been described in the spine, hand, wrist, ankle, foot, and pelvis. Treatment typically includes a combination of surgical debridement and antifungal treatment.An 11-year-old boy presented with a 7-month history of left anterior knee pain. Physical examination revealed mild knee effusion and quadriceps atrophy with focal tenderness to palpation to the distal pole of the patella. Laboratory studies were unremarkable and plain radiographs revealed a radiolucency in the inferomedial aspect of the patella. Magnetic resonance imaging revealed a corresponding focus of increased T2 signal with sclerotic margins and peripheral edema within the patella. Open biopsy with curettage confirmed coccidiomycosis, and the patient was successfully managed with long-term antifungal antibiotics.To our knowledge, this article presents the first known case of coccidioidal osteomyelitis of the patella.