Mark J. Adamczyk

A 50-year Experience With Bone Graft Epiphysiodesis in the Treatment of Slipped Capital Femoral Epiphysis

A “millennium” update of all cases of slipped capital femoral epiphysis treated by bone graft epiphysiodesis between 1950 and 2000 was conducted. All cases were followed for at least 1 year to evaluate the occurrence of re-slippage, avascular necrosis (AVN), chondrolysis, or complications secondary to the surgical approach. This study adds 109 patients and 133 hips to the initial report for a total of 268 patients and 318 hips. The patients include 43 patients with 45 acute slips and 225 patients with 273 chronic slips. The results include three cases of AVN, six cases of re-slippage, one case of chondrolysis, and no surgical approach complications in the acute group. In the chronic group, there were 4 cases of AVN, 17 cases of re-slippage, 4 cases of deep wound infection, and no cases of chondrolysis. The authors suggest that bone graft epiphysiodesis is a reasonable alternative in the treatment of slipped capital femoral epiphysis.

Delayed union and nonunion following closed treatment of diaphyseal pediatric forearm fractures.

Delayed unions and nonunions of diaphyseal pediatric forearm fractures are exceedingly uncommon. In the past they generally have been reported in conjunction with open fracture or initial operative management of these fractures. The authors report six cases that occurred in low-energy, closed fractures initially managed with casting. The cases all occurred in teenage patients from age 13 to 16, and all cases involved the ulna. The mid-diaphysis was the most common location, and this may represent a watershed zone of perfusion with a relatively poor intraosseous blood supply. All of these patients were managed with compression plating with or without bone grafting. Three of these patients had rapid healing in an average of 2 months, while one had an inadequate radiographic record and another was lost to follow-up. The other patient had a more prolonged course to healing after surgery.

Increased chondrocyte apoptosis in growth plates from children with slipped capital femoral epiphysis.

Ultrastructural studies of slipped capital femoral epiphysis (SCFE) growth plates have shown diminished cellularity and marked distortion of the architecture in the proliferative and hypertrophic zones. Chondrocyte degeneration and death were noted at all levels of the hypertrophic and proliferative zones, suggesting an accelerated disturbance in the life-to-death cycle of the chondrocytes. The current study examines the mechanism responsible for the diminished cell number and whether increased programmed cell death (apoptosis) or necrosis was operative. Proximal femoral growth plates from patients with SCFE (three patients) were prepared and sectioned for histochemistry, in situ detection of apoptosis, and immunohistochemistry. The results showed that the diminished cell number is due to an abnormal frequency and distribution of chondrocytes undergoing apoptosis. Although it is unclear whether the increased apoptosis is occurring early or late in the disease, it is highly likely that it is directly linked to pathogenesis.

Clinically Suspected Scaphoid Fractures in Children

Purpose: Scaphoid fractures are often missed in children because of their rarity and difficulty with radiographic diagnosis. Children are often treated for clinically suspected scaphoid fractures although there is no radiographic evidence for fracture on initial evaluation. The 2-fold purpose of this study is (1) to determine how many clinically suspected pediatric scaphoid fractures later became radiographically evident fractures and (2) to identify physical examination findings that suggest a scaphoid fracture when present at initial evaluation. Methods: We performed separate retrospective and longitudinal reviews of children younger than 16 years referred to orthopaedics with traumatic wrist pain from January 1995 to April 2002. A total of 104 cases with high clinical suspicion but no radiographic evidence of scaphoid fracture on initial examination were included. Patients were followed until discharge to determine if they later demonstrated a confirmed fracture. In the longitudinal arm, 7 specific examination findings were recorded. Simple and multiple logistic regressions were used to analyze the data. Results: Thirty-one (30%) of the 104 wrists with no initial radiographic evidence of fracture had a radiographically evident scaphoid fracture at follow-up. In the longitudinal arm (n = 41), the following 3 findings were statistically significant predictors of scaphoid fracture: volar tenderness over the scaphoid (P = 0.010), pain with radial deviation (P = 0.001), and pain with active wrist range of motion (P = 0.015). Presence of any of these findings was associated with a higher likelihood of scaphoid fracture. Conclusion: A high percentage (30%) of clinically suspected scaphoid fractures in children became radiographically evident fractures at follow-up. Volar scaphoid tenderness, radial deviation pain, and pain with active wrist range of motion can be used as signs to increase suspicion for eventual fracture. We recommend that all clinically suspected pediatric scaphoid fractures be immobilized with repeat radiographs and a clinical examination at 2 weeks. Level of Evidence: II

A study in vivo of the effects of a static compressive load on the proximal tibial physis in rabbits

BACKGROUND The effect of compression on the physis is generally defined by the Hueter-Volkmann principle, in which decreased linear growth of the physis results from increased compression. This investigation examined whether mechanically induced compression of rabbit physes causes changes in gene expression, cells, and extracellular components that promote physeal resilience and strength (type-II collagen and aggrecan) and cartilage hypertrophy (type-X collagen and matrix metalloprotease-13). METHODS Static compressive loads (10 N or 30 N) were applied for two or six weeks across one hind limb proximal tibial physis of thirteen-week-old female New Zealand White rabbits (n = 18). The contralateral hind limb in all rabbits underwent sham surgery with no load to serve as an internal control. Harvested physes were divided into portions for histological, immunohistochemical, and quantitative reverse transcription-polymerase chain reaction analysis. Gene expression was statistically analyzed by means of comparisons between loaded samples and unloaded shams with use of analysis of variance and a Tukey post hoc test. RESULTS Compared with unloaded shams, physes loaded at 10 N or 30 N for two weeks and at 10 N for six weeks showed histological changes in cells and matrices. Physes loaded at 30 N for six weeks were decreased in thickness and had structurally disorganized chondrocyte columns, a decreased extracellular matrix, and less intense type-II and X collagen immunohistochemical staining. Quantitative reverse transcription-polymerase chain reaction analysis of loaded samples compared with unloaded shams yielded a significantly (p ≤ 0.05) decreased gene expression of aggrecan and type-II and X collagen and no significant (p > 0.05) changes in the matrix metalloprotease-13 gene expression with increasing load. CONCLUSIONS Compressed rabbit physes generate biochemical changes in collagens, proteoglycan, and cellular and tissue matrix architecture. Changes potentially weaken overall physeal strength, consistent with the Hueter-Volkmann principle, and lend understanding of the causes of pathological conditions of the physis.

Biomechanical stability of bioabsorbable screws for fixation of acetabular osteotomies.

The purpose of this study was to compare the biomechanical stability of triple innominate osteotomies fixed with either bioabsorbable or stainless steel screws. Triple innominate osteotomies were performed on composite hemipelves and fixed with either three 4.5-mm bioabsorbable screws or three stainless steel 4.5-mm screws. Two screws were placed from the iliac wing into the acetabular fragment, and 1 screw was placed from below the acetabular fragment into the iliac wing. Eight specimens for each screw type were biomechanically tested in an anatomical position (replicating weight bearing) and in a flexed and abducted position (replicating spica cast positioning). Specimens were cyclically loaded between 10 and 450 N to simulate the hip contact force in this population. Lower screws were then removed, and specimens were tested under identical conditions. Fragment displacement (mm) and construct stiffness (N/mm) were compared with a 2-way analysis of variance (P < 0.05). There were no significant differences between materials for fragment displacement or construct stiffness. Anatomical position showed significantly less displacement than spica position for both materials. Initial displacement in the spica position was significantly less during lower loads for stainless steel fixation. Bioabsorbable screws demonstrate comparable biomechanical stability to stainless steel screws in anatomical and spica positions at physiological loads. Flexion and abduction of the femur adversely affect the stability of the construct for both materials. Bioabsorbable screws behave similarly to steel screws when stabilizing triple innominate osteotomies and would have the advantage of not requiring a second surgery for screw removal. Confirmation of biocompatibility should be completed before widespread clinical application.

A prospective comparison of computer-navigated and fluoroscopic-guided in situ fixation of slipped capital femoral epiphysis.

Background: Slipped capital femoral epiphysis (SCFE) is usually treated with percutaneous in situ screw fixation to prevent further progression of deformity. The purpose of this investigation is to compare computer navigation (CN) techniques with traditional fluoroscopic (fluoro) techniques for in situ fixation of SCFE. Methods: This study was an IRB-approved prospective study of 39 hip pinnings in 33 children. CN techniques were used in 22 cases and fluoro in 17. The CN and fluoro groups were statistically similar in terms of grade and acuity of the slip. Children were assigned to the groups based on the intraoperative imaging technique used by the attending on call, with 3 surgeons in each group taking equal amounts of call. The “approach-withdraw” technique was used in all cases. Postoperative limited-cut, reduced-dose computed tomography (CT) scans were obtained to evaluate screw placement. This included blinded analysis for screw penetration of the joint, screw tip-to-apex distance, the distance the screw passed to the center of the physis, and attainment of center-center position. The number of pin passes, intraoperative radiation exposure, and operating room (OR) time were also analyzed. Statistics used included ANOVA, the &khgr;2 and median tests. Results: Compared with the fluoro group, CN resulted in more accurate screw placement. There was 1 case of joint penetration in the fluoro group not appreciated intraoperatively but detected on postoperative CT. CN also resulted in statistically significant (P<0.05) reduced screw tip-to-apex distance and distance to the center of the physis. There was no statistically significant difference between the 2 groups in attainment of the center-center position, number of pin passes, or intraoperative radiation exposure. OR time averaged 19 minutes longer in the CN group. There was no case of avascular necrosis or chondrolysis in either of the groups. Conclusions: Compared with traditional fluoro techniques, CN in situ fixation of SCFE results in more accurate screw placement, comparable number of pin passes and intraoperative radiation exposure, and increased OR time. The cost-benefit ratio of this technology requires careful consideration at each individual institution. Level of Evidence: II.

Cranial nerve IX and X impairment after a sports-related Jefferson (C1) fracture in a 16-year-old male: a case report.

Background: Jefferson (C1) fractures are rare cervical spine injuries that usually do not result in cranial nerve (CN) impairment. However, case reports of Collet-Sicard syndrome (impairment of CNs IX-XII) and impairment of CNs IX, X, and XII have been reported. All reported cases involved adult patients in high-impact collisions, such as motor vehicle accidents or falls. To our knowledge, a Jefferson fracture with selective CN impairment due to a low-energy, sports-related injury in a pediatric patient has not been reported. Methods: Chart and radiographic data for a single case were reviewed and reported in a retrospective study approved by the Institutional Review Board of the participating hospital. Results: A 16-year-old male was diagnosed with a Jefferson fracture after a head-to-chest football collision. On computed tomography, the distance between the atlas transverse process and styloid process of the skull was 5 mm right and 10 mm left. Before halo fixation, the patient had vague complaints of dysphagia. These complaints worsened which led to the diagnosis of CN IX and X impairment and placement of a feeding tube. The fracture healed uneventfully, the dysphagia symptoms resolved, and the halo fixation and feeding tube were removed. The patient returned to all activities, but was instructed to avoid participation in contact sports. Conclusions: This was the first report of selective CN impairment in a pediatric patient with a Jefferson fracture resulting from a low-impact sports-related injury. Careful monitoring of the patient complaints led to appropriate treatment. Further studies into the spatial relationship between the transverse process of the atlas in relation to the styloid process of the skull may be warranted. Level of Evidence: Level V, case report.

Evaluation of Limited Screw Density Pedicle Screw Constructs in Posterior Fusions for Adolescent Idiopathic Scoliosis

STUDY DESIGN Retrospective case series. OBJECTIVES To compare radiographic and clinical outcomes in posterior spine fusions with pedicle screw instrumentation of varying screw densities in the treatment of adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA Posterior spinal fusion with pedicle screw instrumentation is the mainstay of surgical treatment for AIS. The most commonly used construct consists of screws placed at every level on the concave side of the deformity and nearly every level on the convex side. However, some surgeons have begun using constructs with fewer pedicle screws. The literature comparing outcomes of these differing pedicle screw constructs is limited. METHODS Fifty-two consecutive cases of posterior spinal fusions for AIS performed by four surgeons were reviewed. High screw density constructs were used in 26 cases and limited screw density constructs in 26 cases. Construct characteristics and radiographic measurements were compared preoperatively and at last follow-up. Operative time and estimated costs were also evaluated. Student t tests were used to compare the groups with p < .05 considered significant. RESULTS There was no significant difference in magnitude of correction for the high versus limited screw density group initially (38.5° vs. 34.9°, p = .093) or at final follow-up (36.9° vs. 32.2°, p = .054). Sagittal alignment, coronal balance, and translation of the major apical vertebra were comparable and stable in both groups. The high versus limited screw density group utilized significantly more pedicle screws (16.8 vs. 11.6 screws, p < .0001), had longer operative times (309 vs. 267 minutes, p = .007), and had additional estimated direct costs of

Fibular Allograft and Demineralized Bone Matrix for the Treatment of Slipped Capital Femoral Epiphysis.

5,800. CONCLUSIONS Excellent curve correction, stability, and balance can be achieved using fewer screws than commonly used in posterior pedicle screw fusions for AIS. Operative time is reduced, and risk and cost are decreased with the use of limited screw density constructs. LEVEL OF EVIDENCE III.