Suprascapular Ligament Release From an Anterior Approach: An Anatomic Feasibility Study.

PURPOSE: The results of spinal accessory to suprascapular nerve transfers have been less reliable than other nerve transfers in the upper limb, possibly owing to compression of the nerve by the suprascapular ligament. The posterior approach has been advocated to allow for release of the ligament. The purpose of this study was to determine whether a ligament release is possible from the anterior approach. METHODS: Nine fresh-frozen cadavers were dissected to determine whether the ligament could be approached and released from the anterior approach. Complete ligament release was demonstrated by subluxation of the nerve out of the suprascapular notch. RESULTS: Ligament release was achieved in all specimens, although in one, confirmation of complete release required a posterior approach. CONCLUSIONS: Release of the suprascapular ligament to eliminate a potential source of compression of the suprascapular nerve during spinal accessory to suprascapular nerve transfer is possible through an anterior approach. CLINICAL RELEVANCE: Release of the suprascapular ligament through an anterior approach allows this procedure to be performed through the same approach as brachial plexus exploration and spinal accessory nerve to suprascapular nerve transfer. This method could reduce surgical time and patient repositioning and avoid additional incisions.

Blinded Ultrasound Examination of the Subscapularis Following Anatomic Shoulder Arthroplasty.

BACKGROUND: The subscapularis tendon is commonly released during shoulder arthroplasty, and its integrity and repair postoperatively have been shown important to help maximize patient function. However, diagnosing subscapular tendon failure can be difficult with magnetic resonance imaging secondary to metal artifact as well as very costly. PURPOSE: The purpose of this study was to assess the utility of ultrasound imaging in evaluating subscapularis integrity at specific time points following shoulder arthroplasty, in a blinded fashion. Secondarily, we report on the correlation between the condition of the subscapularis and quality-of-life outcome measures. STUDY DESIGN: Prospective case series. METHODS: Ultrasounds were completed preoperatively and postoperatively at 1 week as well as at 1, 3, and 6 months. Each was read by a single musculoskeletal radiologist and categorized as "intact," "torn," or "unclear." Clinical outcome was evaluated using the Western Ontario Osteoarthritis Shoulder (WOOS) index at these same time points. RESULTS: The final study group consisted of 35 procedures in 33 patients (19 females and 14 males, mean age 66 ± 9 years). Three patients had postoperative subscapularis failures that were confirmed in the operating room at the time of repair. Of 24 sonographs categorized as "unclear" in the postoperative period, the majority (n = 12, 50%) were taken at 1 week. Compared to preoperative scores, patients had lower WOOS scores at 1, 3, and 6 months postoperatively (P < .001). Correlation analysis did not reveal an association between the ultrasound readings and the WOOS scores postoperatively. CONCLUSION: The utility of ultrasound examination of the subscapularis tendon following shoulder arthroplasty is limited by timing and may be most useful when used by the physician within clinical context. Significant improvement was noted in disease-specific quality-of-life scores regardless of the status of the subscapularis tendon as read on ultrasound.

Elevated Radiation Exposure Associated With Above Surface Flat Detector Mini C-Arm Use.

Background: This study aims to test the hypothesis that: (1) radiation exposure is increased with the intended use of Flat Surface Image Intensifier (FSII) units above the operative surface compared with the traditional below-table configuration; (2) this differential increases in a dose-dependent manner; and (3) radiation exposure varies with body part and proximity to the radiation source. Methods: A surgeon mannequin was seated at a radiolucent hand table, positioned for volar distal radius plating. Thermoluminescent dosimeters measured exposure to the eyes, thyroid, chest, hand, and groin, for 1- and 15-minute trials from a mini C-arm FSII unit positioned above and below the operating surface. Background radiation was measured by control dosimeters placed within the operating theater. Results: At 1-minute of exposure, hand and eye dosages were significantly greater with the flat detector positioned above the table. At 15-minutes of exposure, hand radiation dosage exceeded that of all other anatomic sites with the FSII in both positions. Hand exposure was increased in a dose-dependent manner with the flat detector in either position, whereas groin exposure saw a dose-dependent only with the flat detector beneath the operating table. Conclusions: These findings suggest that the surgeon's hands and eyes may incur greater radiation exposure compared with other body parts, during routine mini C-arm FSII utilization in its intended position above the operating table. The clinical impact of these findings remains unclear, and future long-term radiation safety investigation is warranted. Surgeons should take precautions to protect critical body parts, particularly when using FSII technology above the operating with prolonged exposure time.

Distal Radius Fractures in a Functional Quadruped: Spanning Bridge Plate Fixation of the Wrist.

Patients who require assistive devices with their hands for mobilization are called functional quadrupeds. These patients pose a unique challenge after they have a distal radius fracture, as their injury not only limits the wrist but also compromises ambulation. The authors propose a different treatment strategy for functional quadrupeds to improve mobilization and weight-bearing with the injured limb after a distal radius fracture. In this article, the authors define the functional quadruped and describe their technique of spanning bridge plate fixation with a retrospective review of patient outcomes.

Mini C-Arm Fluoroscopy: Does Its Configuration Matter for Radiation Exposure to the Surgeon?

BACKGROUND: The risk of occupational radiation exposure to the surgeon associated with the use of a mini C-arm has yet to reach a wide consensus. Using a distal radius fracture surgery model, we tested the hypothesis that radiation exposure to the surgeon's critical body parts is independent of mini C-arm configuration. METHODS: An anthropomorphic mannequin (representing the upper body of a 60" male surgeon) was seated at a hand table as if operating on a volar-plated wrist Sawbone model. Thermoluminescent dosimeters measured radiation exposure to the surgeon's eyes, thyroid, chest, hand, and groin from a mini C-arm fluoroscopy unit in 3 commonly used configurations: vertical (source above table), inverted (source below table), and horizontal (with beam parallel to table surface). The fluoroscope scanned the wrist model for 15 continuous minutes in triplicate for each orientation. RESULTS: Radiation to the hand was significantly greatest in all mini C-arm positions compared with all other anatomic sites irrespective of C-arm position. Hand radiation exposure was greatest in the horizontal position (2887.09 mrem), versus the vertical and inverted positions (59.79 mrem, 31.10 mrem, P < .001). Eye radiation exposure was significantly greater in the inverted position (2.33 mrem) compared with the vertical (0.67 mrem, P = .024), and horizontal positions (0.33 mrem, P = .012). No significant difference in radiation exposure was found at the thyroid, chest, and groin sites, at each of the 3 C-arm configurations. CONCLUSIONS: The model's hand received almost 1000 times more radiation exposure than all other anatomic sites with statistically greatest radiation exposure sustained in the horizontal position. Eye radiation exposure with the C-arm in the inverted position (below the table) was also significantly greater.

Combination therapy with BMP-2 and a systemic RANKL inhibitor enhances bone healing in a mouse critical-sized femoral defect.

Recombinant human BMP-2 (rhBMP-2) is a potent osteoinductive agent, but has been associated not only with bone formation, but also osteoclastogenesis and bone resorption. Osteoprotegerin (OPG) is a RANKL inhibitor that blocks differentiation and function of osteoclasts. We hypothesized that the combination of local BMP-2 (recombinant protein or a product of gene therapy) plus systemic OPG-Fc is more effective than BMP-2 alone in promoting bone repair. To test this hypothesis we used a mouse critical-sized femoral defect model. Col2.3eGFP (osteoblastic marker) male mice were treated with rhBMP-2 (group I), rhBMP-2 and systemic OPG (group II), rhBMP-2 and delayed administration of OPG (group III), mouse BM cells transduced with a lentiviral vector containing the BMP-2 gene (LV-BMP-2; group IV), LV-BMP-2 and systemic OPG (group V), a carrier alone (group VI) and administration of OPG alone (group VII). All bone defects treated with BMP-2 (alone or combined with OPG) healed, whereas minimal bone formation was noted in animals treated with the carrier alone or OPG alone. MicroCT analysis showed that bone volume (BV) in rhBMP-2+OPG and LV-BMP-2+OPG groups was significantly higher compared to rhBMP-2 alone (p<0.01) and LV-BMP-2 alone (p<0.001). Similar results were observed in histomorphometry, with rhBMP-2 alone defects exhibiting significantly lower bone area (B.Ar) compared to rhBMP-2+OPG defects (p<0.005) and LV-BMP-2 defects having a significantly lower B.Ar compared to all BMP-2+OPG treated groups (p≤0.01). TRAP staining demonstrated a major osteoclast response in the groups that did not receive OPG (rhBMP-2, LV-BMP-2 and sponge alone) beginning as early as 7days post-operatively. In conclusion, we demonstrated that locally delivered BMP-2 (recombinant protein or gene therapy) in combination with systemically administered OPG improved bone healing compared to BMP-2 alone in a mouse critical-sized bone defect. These data indicate that osteoclasts can diminish healing responses to BMP-2 and that RANKL inhibition may thus accentuate BMP-2 efficacy.

Systemic Administration of Sclerostin Antibody Enhances Bone Morphogenetic Protein-Induced Femoral Defect Repair in a Rat Model.

BACKGROUND: Recombinant human bone morphogenetic protein (rhBMP)-2 is a potent osteoinductive agent; however, its clinical use has been reduced because of safety and efficacy concerns. In preclinical studies involving a critical-sized defect in a rat model, sclerostin antibody (Scl-Ab) treatment increased bone formation within the defect but did not result in reliable healing. The purpose of the current study was to evaluate bone repair of a critical-sized femoral defect in a rat model with use of local implantation of rhBMP-2 combined with systemic administration of Scl-Ab. METHODS: A critical-sized femoral defect was created in rats randomized into three treatment groups: local rhBMP-2 and systemic Scl-Ab (Scl + BMP), local rhBMP-2 alone, and collagen sponge alone (operative control). The Scl + BMP group received local rhBMP-2 (10 µg) on a collagen sponge placed within the defect intraoperatively and then twice weekly injections of Scl-Ab (25 mg/kg) administered postoperatively. The femora were evaluated at twelve weeks with use of radiography, microcomputed tomography (microCT), histomorphometric analysis, and biomechanical testing. RESULTS: At twelve weeks, all Scl + BMP and rhBMP-2 only samples were healed. No femora healed in the operative control group. Histomorphometric analysis demonstrated more bone in the Scl + BMP samples than in the samples treated with rhBMP-2 alone (p = 0.029) and the control samples (p = 0.003). MicroCT revealed that the Scl + BMP group had a 90% greater bone volume within the defect region compared with the rhBMP-2 group and a 350% greater bone volume compared with the operative control group (p < 0.001). Biomechanical testing showed that the group treated with Scl + BMP had greater torsional strength and rigidity compared with the rhBMP-2 group (p < 0.001 and p = 0.047) and the intact femoral control group (p < 0.001). Torque to failure was lower in the rhBMP-2 group compared with the intact femoral control group (p < 0.002). Mean energy to failure was higher in the Scl + BMP samples compared with the rhBMP-2 only samples (p = 0.001). CONCLUSIONS: In a critical-sized femoral defect in a rat model, local rhBMP-2 combined with systemic administration of Scl-Ab resulted in more robust healing that was stronger and more rigid than results for rhBMP-2 alone and intact nonoperative femora. CLINICAL RELEVANCE: Our study demonstrated that combining an osteoinductive agent with a systemically administered antibody that promotes bone formation can enhance bone repair and has potential as a therapeutic regimen in humans.

Combination therapy with PTH and DBM cannot heal a critical sized murine femoral defect.

Orthopaedic surgeons continue to search for cost-effective bone graft substitutes to enhance bone repair. Teriparatide (PTH 1-34) and demineralized bone matrix (DBM) have been used in patients to promote bone healing. We evaluated the efficacy of PTH and DBM in healing a critical sized femoral defect in three lineage-specific transgenic mice expressing Col3.6GFPtopaz (pre-osteoblastic marker), Col2.3GFPemerald (osteoblastic marker) and α-SMA-Cherry (pericyte/myofibroblast marker). Mid-diaphyseal defects measuring 2 mm in length were created in the central 1/3 of mice femora using a circular saw and stabilized with an alveolar distractor device and cerclage wires. Three groups were evaluated: Group I, PTH 30 µg/kg injection daily, Group II, PTH 30 µg/kg injection daily + DBM, and Group III, DBM + 30µL saline injection. PTH was given for 28 days or until the time of sacrifice. Animals were sacrificed at 7, 14, 28, and 56 days. Radiographs at the time of sacrifice were evaluated using a 5-point scaled scoring system. Radiographs showed a lack of healing across all treatment groups at all time points: Group I, 1.57 +/- 0.68; Group II, 3.00 +/- 1.29; and Group III, 2.90 +/- 1.03. Bone formation in the defect as measured by radiographic healing score was significantly better at 56 days in Groups II (p = 0.01) and III (p < 0.01) compared to Group I. Across all treatment groups and time points the defects were largely absent of osteoprogenitor cells based on gross observation of frozen histology and quantitation of cellular based histomorphometric parameters. Quantitation of frozen histologic slides showed a limited osteoprogenitor response to PTH and DBM. Our results suggest that the anabolic agent teriparatide is unable to induce healing in a critical sized mouse femoral defect when given alone or in combination with the DBM preparation we used as a local bone graft substitute.

Pronator syndrome and anterior interosseous nerve syndrome.

Dysfunction of the median nerve at the elbow or proximal forearm can characterize two distinct clinical entities: pronator syndrome (PS) or anterior interosseous nerve (AIN) syndrome. PS is characterized by vague volar forearm pain, with median nerve paresthesias and minimal motor findings. AIN syndrome is a pure motor palsy of any or all of the muscles innervated by that nerve: the flexor pollicis longus, the flexor digitorum profundus of the index and middle fingers, and the pronator quadratus. The sites of anatomic compression are essentially the same for both disorders. Typically, the findings of electrodiagnostic studies are normal in patients with PS and abnormal in those with AIN syndrome. PS is a controversial diagnosis and is typically treated nonsurgically. AIN syndrome is increasingly thought to be neuritis and it often resolves spontaneously following prolonged observation. Surgical indications for nerve decompression include persistent symptoms for >6 months in patients with PS or for a minimum of 12 months with no signs of motor improvement in those with AIN syndrome.

Urine matrix metalloproteinases (MMPs) as biomarkers for the progression of fracture healing.

Whilst the majority of fractures heal normally, it is estimated that ∼10% of fractures exhibit some level of delayed or impaired healing. Although radiography is the primary diagnostic tool to assess the progression of fracture healing, radiographic features only qualitatively correlate with tissue level increases in mineral content and do not quantitatively measure underlying biological processes that are associated with the progression of healing. Specific metaloproteinases have been shown to be essential to processes of both angiogenesis and mineralised cartilage resorption and bone remodelling at different phases of fracture healing. The aim of this study was to determine the potential of using a simple urine based assay of the activity of two MMPs as a means of assessing the biological progression of fracture healing through the endochondral phase of healing. Using a standard mid-diaphyseal murine model of femoral fracture, MMP9 and MMP13 proteins and enzymatic activity levels were quantified in the urine of mice across the time-course of fracture healing and compared to the mRNA and protein expression profiles in the calluses. Both urinary MMP9 and MMP13 protein and enzymatic activity levels, assessed by Western blot, zymogram and specific MMP fluorometric substrate assays, corresponded to mRNA expression and immunohistologic assays of the proteins within callus tissues. These studies suggest that urinary levels of MMP9 and MMP13 may have potential as metabolic markers to monitor the progression of fracture healing.