Thread Delamination in 4.5 mm AO Cannulated Screws: A Small Case Series in the Pediatric Trauma Population.

BACKGROUND: Thread delamination associated with cannulated screws have been reported but likely represent an under-recognized complication in the orthopaedic literature. The purpose of this study is to report the occurrence of repeated hardware failures through thread delamination in the setting of a commonly used orthopaedic cannulated screw implant in a small cohort involving pediatric fracture care at a single academic level I trauma center. METHODS: Between August 2015 and December 2020, 9 cases of hardware failure associated with 4.5 mm arbeitsgemeinschaft für osteosynthesefragen cannulated stainless-steel screws were identified within a pediatric orthopaedic division at a single academic level I trauma center. Three cases were excluded, and 6 cases of thread delamination were retrospectively reviewed. RESULTS: Six cases of thread delamination comprised a cohort of patients with a mean age of 13.7 years (range: 12 to 15 y). All cases involved 4.5 mm arbeitsgemeinschaft für osteosynthesefragen cannulated screws, including 5 partially threaded and 1 fully threaded screw. Five cases involved open reduction and internal fixation of incarcerated medial humeral epicondylar fragments and the other case was an open reduction and internal fixation of a displaced medial malleolar fracture. Five of these occurred within a recent 18-month period of time. There were 4 cases of partial, distal thread delamination, 1 case of partial proximal thread delamination and another case of complete thread delamination which had unwound into the tibiotalar joint and required an anterior ankle arthrotomy to retrieve the thread. None of the 5 patients in this series who currently harbor a retained thread have experienced symptoms because of this issue. CONCLUSIONS: Thread delamination associated with cannulated screw implantation likely represents an under-reported phenomenon in orthopaedic surgery. In cases where retained, delaminated threads exist, these do not appear to cause short-term concern. LEVEL OF EVIDENCE: Level IV-case series.

Is There Value in Having Radiology Provide a Second Reading in Pediatric Orthopaedic Clinic?

BACKGROUND: The Joint Commission on Accreditation of Healthcare Organizations specifically mandates the dual interpretation of musculoskeletal radiographs by a radiologist in addition to the orthopaedist in all hospital-based orthopaedic clinics. Previous studies have questioned the utility of this practice. The purpose of this study was to further investigate the clinical significance of having the radiologist provide a second interpretation in a hospital-based pediatric orthopaedic clinic. METHODS: A retrospective review was performed of all patients who had plain radiographs obtained in the pediatric orthopaedic clinic at an academic children's hospital over a 4-month period. For each radiographic series, the orthopaedist's note and the radiology interpretation were reviewed and a determination was made of whether the radiology read provided new clinically useful information and/or a new diagnosis, whether it recommended further imaging, or if it missed a diagnosis that was reflected in the orthopaedist's note. The hospital charges associated with the radiology read for each study were also quantified. RESULTS: The charts of 1570 consecutive clinic patients who were seen in the pediatric orthopaedic clinic from January to April, 2012 were reviewed. There were 2509 radiographic studies performed, of which 2264 had both a documented orthopaedist's note and radiologist's read. The radiologist's interpretation added new, clinically important information in 1.0% (23/2264) of these studies. In 1.7% (38/2264) of the studies, it was determined that the radiologist missed the diagnosis or clinically important information that could affect treatment. The total amount of the professional fees charged for the radiologists' interpretations was $87,362. On average, the hospital charges for each occurrence in which the radiologist's read provided an additional diagnosis or clinically important information beyond the orthopaedist's note were $3798. CONCLUSIONS: The results of this study suggest that eliminating the requirement to have the radiologist interpret radiographs in the pediatric orthopaedic clinic would have few clinical consequences. LEVEL OF EVIDENCE: Level III-This is a diagnostic retrospective cohort study.

The effect of neutron radiation on conventional and highly cross-linked ultrahigh-molecular-weight polyethylene wear.

The effects of a sarcoma therapy dose level neutron radiation on oxidation and wear were compared between conventional (N2\Vac, Stryker Orthopedics, Mahwah, NJ) and highly cross-linked (Crossfire, Stryker Orthopedics) ultrahigh-molecular-weight polyethylene acetabular liners. Liners were exposed to 15 Gy, a typical sarcoma treatment dose. Wear testing was conducted on a hip simulator. Transvinylene and oxidation indices were measured to determine if significant radiolytic reactions and oxidation occurred after the neutron beam exposure. The neutron bombardment produced further oxidation in both N2\Vac and Crossfire liners. Surprisingly, neutron radiation caused 62% increase in wear for N2\Vac but 0% change for the Crossfire acetabular liners. This study suggested that when joint implants are exposed to neutron beam radiation therapy, the conventional polyethylene liner is at risk for rapid wear.

The effect of muscle fatigue on in vivo tibial strains.

Stress fracture is a common musculoskeletal problem affecting athletes and soldiers. Repetitive high bone strains and strain rates are considered to be its etiology. The strain level necessary to cause fatigue failure of bone ex vivo is higher than the strains recorded in humans during vigorous physical activity. We hypothesized that during fatiguing exercises, bone strains may increase and reach levels exceeding those measured in the non-fatigued state. To test this hypothesis, we measured in vivo tibial strains, the maximum gastrocnemius isokinetic torque and ground reaction forces in four subjects before and after two fatiguing levels of exercise: a 2km run and a 30km desert march. Strains were measured using strain-gauged staples inserted percutaneously in the medial aspect of their mid-tibial diaphysis. There was a decrease in the peak gastrocnemius isokinetic torque of all four subjects' post-march as compared to pre-run (p=0.0001), indicating the presence of gastrocnemius muscle fatigue. Tension strains increased 26% post-run (p=0.002, 95 % confidence interval (CI) and 29% post-march (p=0.0002, 95% CI) as compared to the pre-run phase. Tension strain rates increased 13% post-run (p=0.001, 95% CI) and 11% post-march (p=0.009, 95% CI) and the compression strain rates increased 9% post-run (p=0.0004, 95% CI) and 17% post-march (p=0.0001, 95% CI). The fatigue state increases bone strains well above those recorded in rested individuals and may be a major factor in the stress fracture etiology.

The effect of hyaluronic acid on a rabbit model of full-thickness cartilage repair.

The current study investigated whether hyaluronate exerts a beneficial effect on articular cartilage repair. Nineteen rabbits had bilateral knee arthrotomies, and 2-mm full-thickness cartilage defects were created on each medial femoral condyle. Rabbits received intraarticular injections (0.5 mL) of hyaluronic acid once a week for 3 weeks in the right knee, started at either 1 or 3 weeks after injury. The left knees, which served as controls, were injected with 0.5 mL normal saline. Cohorts of each group were euthanized at 2 and 6 months, and histologic sections of the injury sites were evaluated for repair tissue. No significant differences were seen in the quantity or quality of the repair tissue at either 2 or 6 months. Hyaluronate and saline-treated defects showed persistent fibrillation, poor matrix staining, and incomplete void filling, irrespective of the injection timing. Hyaluronate did not provide protection to zones peripheral to the injury site, and did not significantly alter the healing process in this model of acute full-thickness cartilage injuries.

Compartment syndrome after acute rupture of the peroneus longus in a high school football player: a case report.

We report the case of a young athlete who sustained an inversion injury to his ankle and presented several hours later with leg pain out of proportion to the injury. Pressure measurements suggested a lateral compartment syndrome and he underwent an emergency fasciotomy. The case is described and recommendations for diagnosis and treatment are given. Acute compartment syndrome of the lower extremity is an orthopedic emergency. Expedient release by emergent fasciotomy can minimize the likelihood of serious consequences such as myonecrosis and ischemic contracture. Most commonly, compartment syndrome is the result of acute high-energy trauma and typically is managed by the orthopedic traumatologist.

Acute synovitis of the knee resulting from intra-articular knee penetration as a complication of flexible intramedullary nailing of pediatric femur fractures: report of two cases.

Management of pediatric femur fractures using flexible intramedullary nail fixation is widely accepted. Few complications have been reported in the literature; these include primarily malunions and nonunions. The authors present two cases of a previously unreported complication-acute synovitis of the knee following intra-articular penetration of the knee joint by migration of a flexible nail.

Pediatric orthopedic trauma: principles in management.

Optimal management of pediatric orthopedic trauma requires understanding the unique characteristics of the immature musculoskeletal system. The principles of pediatric orthopedic trauma management include anticipating future growth and bone remodeling potential, minimizing physeal injury, and aggressive treatment of open fractures and compartment syndromes. This article discusses the fundamentals of the pediatric musculoskeletal system and pediatric orthopedic trauma management in general and as they apply to specific injuries.