Improved restoration of biomechanical factors using a narrow-box shape reconstruction compared to a wide one in superior capsular reconstruction for irreparable supraspinatus tendon tears. A biomechanical study using a static shoulder simulator.

PURPOSE: To biomechanically compare superior glenohumeral translation, subacromial contact pressures and area in a box-shape reconstruction using the long head of biceps tendon (LHBT) in an irreparable supraspinatus tendon tear model. METHODS: Seven cadaveric shoulders (mean age 61 years; range 32-84 years; SD 22.3) were tested with a custom testing rig used to evaluate superior translation, subacromial contact pressures and areas at 0°, 30° and 60° of glenohumeral abduction. Conditions tested included the native state, a complete tear of the supraspinatus tendon, a wide box-shaped, double-bundle LHBT superior capsular reconstruction (wide BS-SCR), and a narrow box-shaped, double-bundle LHBT superior capsular reconstruction (narrow BS-SCR). RESULTS: Compared to the wide box-shape SCR, the narrow box-shape SCR had statistically significant lower median contact pressure at 30° and 60°. The subacromial contact area showed a statistically significant difference at 0° (p=0.001) and 30° (p=0.004) for the narrow compared to wide box-shape SCR. At an abduction angle of 0°, the narrow SCR could restore superior translation statistically significant better compared to the wide construct. For all angles, the wide and narrow box-shaped SCR increased the median subacromial distance statistically significantly. The contact areas in 30° and 60° of abduction were higher for all scenarios, both peaking in the intact state in 30° with approximately 600 mm2. CONCLUSIONS: In comparison to a wide box-shape, a narrow box-shape SCR using the LHBT has biomechanical advantages in regard of subacromial contact pressures, the subacromial contact areas as well as the acromiohumeral distance. The width of the reconstruction therefore has direct influence in the success of the technique.

Early range of motion results in good elbow function following conservative treatment of non-displaced radial head fractures.

INTRODUCTION: The aim of this study was to evaluate the range of motion (ROM), elbow function and predictors for good elbow function after conservative treatment of non-displaced radial head fractures. MATERIAL AND METHODS: All patients with non-displaced radial head fractures (displacement < 2 mm), that were diagnosed between January 1st 2017 and December 31st 2021 in a level I trauma center, were included in this retrospective case series and the charts were evaluated for ROM and elbow function. Elbow function was categorized as "good" or "bad" depending on the ROM measured defined by Morrey et al. Overall, 73 patients (33 male, 40 female) with an average age of 38 years (+/- 13 years) could be included. RESULTS: Conservative treatment had good clinical results for ROM and elbow function. After 6 weeks mean flexion was 131° (SD 13°), extension 8° (SD 7°), Pronation 83° (SD 11°) and Supination 83° (SD 13). Patients with a good elbow function after one week showed a good elbow function after completing the treatment. CONCLUSIONS: A clinical assessment after one week should always be performed and the study showed that it is a good predictor for good elbow function. In cases of bad elbow function further controls should be considered.

Acetabular cortical and cancellous bone density and radiolucent lines after cemented total hip arthroplasty: a prospective study using computed tomography and plain radiography.

INTRODUCTION: The aim of this prospective study was to evaluate load-transfer mechanisms and stress patterns of periacetabular cortical and cancellous bone after cemented total hip arthroplasty (THA) in vivo using computed tomography (CT) assisted osteodensitometry. In addition we analyzed the efficacy of CT in detecting radiolucent lines around the acetabular component compared to plain radiography. MATERIALS AND METHODS: Twenty-two cemented acetabular cups were investigated using conventional sequential axial CT scans (Ø 8 days and 26 months post-OP) and plain radiography (Ø 5 days and 40 months post-OP). CT assisted osteodensitometry was used to determine cancellous and cortical bone bone density (BD). Radiolucent lines were evaluated using both CT and plain radiography. RESULTS: Significant BD loss at the time of follow-up was only detectable ventral to the cup (cortical bone: -16%, P = 0.001; cancellous bone: -31%, P = 0.001). The BD changes dorsal and cranial to the cup were not significant. Postoperatively no radiolucent lines were observed in the cement-bone interface by CT, while on plain radiography acetabular lucent lines were seen in 12 out of 22 cases. CONCLUSION: CT-osteodensitometry has the technical ability to discriminate between cortical and cancellous bone structures with respect to strain-adapted remodeling: sufficient cancellous and cortical bone stock remained dorsal and cranial to the cup indicative of a balanced load transfer to these regions. CT-osteodensitometry has the potential to become an effective instrument for quality control in THA and the method of choice for in vivo determination of periprosthetic BD. In contrast, plain radiography is more suitable for the early detection of radiolucent lines compared to axial CT scans.

Ultrasound-guided spinal fracture repositioning, ligamentotaxis, and remodeling after thoracolumbar burst fractures.

STUDY DESIGN: Computed tomography aided evaluation of spinal decompression by ultrasound-guided spinal fracture repositioning, ligamentotaxis, and remodeling after thoracolumbar burst fractures. OBJECTIVES: To determine the necessity of spinal canal widening by ultrasound-guided fracture repositioning for fractures with and without neurologic deficit. SUMMARY OF BACKGROUND DATA: Ultrasound-guided spinal fracture repositioning is an alternative new approach. Reports have varied concerning ligamentotaxis and remodeling. METHODS: Computed tomography aided planimetry of the spinal canal (64 consecutive burst fractures) and neurologic evaluation by Frankel grades. RESULTS: Ultrasound-guided spinal fracture repositioning (n = 37) reduced the stenosis of the spinal canal area from 45% before surgery to 20% after surgery of the estimated original area. Fifteen patients had a primary neurologic deficit, which improved markedly in 11 cases after treatment. Patients with neurologic symptoms had a greater preoperative spinal stenosis than those without. No correlation was seen between the degree of pretreatment spinal stenosis, fracture type, and severity of the neurologic deficit. Ligamentotaxis (n = 27) reduced the stenosis from 30% before surgery to 18% after surgery and remodeling (n = 11) from 25% after surgery to 13% after metal removal. CONCLUSION: Ultrasound-guided fracture repositioning is an efficient method for spinal canal decompression of burst fractures with neurologic symptoms. The marked degree of widening of the spinal canal due to the effects of ligamentotaxis and remodeling may render the reposition of retropulsed fragments unnecessary in cases of fractures without a neurologic deficit.