Clinical results of surgical treatment for femoral neck fractures with the Targon® FN.

84 cases (male 15 cases, female 69 cases) of intracapsular femoral neck fractures treated with the Targon® FN (TFN) were available for review. Mean patient age was 74.0 years (range 36-100 years). 55 fractures were undisplaced whereas 29 were displaced. Mean follow-up term was 16.4 months. We surveyed patient mobility before injury and after operation as well as postoperative complications. On a four-stage mobility scale we found 3/55 patients with undisplaced fractures loosing mobility by more than one grade (5.5%), whereas 5/29 (17.2%) displayed this kind of functional decline after displaced fractures. Overall postoperative complication rate was 10.7% (9 cases). These complications included nonunion (1 case), avascular necrosis (7 cases) and peri-implant fracture (1case). Internal fixation with the TFN seems to have an acceptable complication rate in both undisplaced and displaced fractures compared to other recent studies.

Role of sodium channels in recovery of sciatic nerve-stretch injury in rats.

INTRODUCTION: To elucidate the mechanism of functional recovery after gradual nerve-stretch injury, we used rats in which the femur length was increased by 15 mm at 1.5 mm/day. METHODS: We performed electrophysiology, mRNA analysis of tetrodotoxin-resistant voltage-gated sodium channels (TTX-R VGSCs) in dorsal root ganglia, and histology of unmyelinated sciatic nerve fibers and examined pain thresholds at 1, 10, 20, and 30 days after cessation of lengthening. RESULTS: Electrophysiology revealed conduction block after cessation that recovered after 30 days. TTX-R VGSC levels decreased immediately after cessation but were restored after 10 (Nav1.9) or 20 (Nav1.8) days. Histology revealed that injured unmyelinated nerve fibers regenerate 30 days after cessation. Pain threshold decreased gradually during lengthening but had not recovered to the control group level after 30 days. CONCLUSIONS: Early restoration of TTX-R VGSC mRNA in dorsal root ganglia preceded functional recovery of stretched nerves before regeneration of injured unmyelinated nerve fibers.

Complications and fixation techniques of trochanteric fractures with the TARGON(®) PF.

The purpose of this study was to analyse clinical results of elderly patients with trochanteric fractures that were treated with use of TARGON(®) PF nail. Overall, 494 patients (113 males) were available for this study. On the basis of Jensen classification, there were 76 cases in type I, 164 cases in type II, 70 in type III, 129 in type IV and 55 in type V. (1) Sliding amount of lag screw in relation to the Jensen classification, (2) sliding amount of lag screw according to the Ikuta's classification that categorises the reduction in lateral view in three, Subtype A, Subtype N and Subtype P, (3) sliding amount of lag screw in correlation between Jensen classification and Ikuta's classification and (4) postoperative complications (9 cases; 1.7%) were assessed. Cut-out and back-out cases were seen in 6 cases (1.1%), and these severe complications were evaluated in details. In correlation between Jensen classification and Ikuta's classification, the excessive sliding of lag screw was prominent with the Subtype P, which was preoperatively in Jensen type III or V. Cut-out or back-out cases were caused either from (1) Subtype P that were preoperatively Jensen types III or V, or from (2) the fracture where there was bony defect anteriorly. Therefore, special care must be taken for these types.

Cellular and extracellular matrix changes in anterior cruciate ligaments during human knee aging and osteoarthritis.

INTRODUCTION: Anterior cruciate ligament (ACL) degeneration is observed in most osteoarthritis (OA)-affected knee joints. However, the specific spatial and temporal relations of these changes and their association with extracellular matrix (ECM) degeneration are not well understood. The objective of this study was to characterize the patterns and relations of aging-related and OA-associated changes in ACL cells and the ECM. METHODS: Human knee joints from 80 donors (age 23 through 94) were obtained at autopsy. ACL degeneration was assessed histologically by using a quantitative scoring system. Tissue sections were analyzed for cell density, cell organization, ECM components, ECM-degrading enzymes and markers of differentiation, proliferation, and stem cells. RESULTS: Total cell number in normal ACL decreased with aging but increased in degenerated ACL, because of the formation of perivascular cell aggregates and islands of chondrocyte-like cells. Matrix metalloproteinase (MMP)-1, -3, and -13 expression was reduced in aging ACL but increased in degenerated ACL, mainly in the chondrocyte-like cells. Collagen I was expressed throughout normal and degenerated ACL. Collagen II and X were detected only in the areas with chondroid metaplasia, which also expressed collagen III. Sox9, Runt-related transcription factor 2 (Runx2), and scleraxis expression was increased in the chondrocyte-like cells in degenerated ACL. Alpha-smooth muscle actin (α-SMA), a marker of myofibroblasts and the progenitor cell marker STRO-1, decreased with aging in normal ACL. In degenerated ACL, the new cell aggregates were positive for α-SMA and STRO-1. CONCLUSIONS: ACL aging is characterized by reduced cell density and activation. In contrast, ACL degeneration is associated with cell recruitment or proliferation, including progenitor cells or myofibroblasts. Abnormally differentiated chondrocyte-like cell aggregates in degenerated ACL produce abnormal ECM and may predispose to mechanical failure.

Clinical results of arthroscopic superior capsule reconstruction for irreparable rotator cuff tears.

PURPOSE: The objective of this study was to investigate the clinical outcome and radiographic findings after arthroscopic superior capsule reconstruction (ASCR) for symptomatic irreparable rotator cuff tears. METHODS: From 2007 to 2009, 24 shoulders in 23 consecutive patients (mean, 65.1 years) with irreparable rotator cuff tears (11 large, 13 massive) underwent ASCR using fascia lata. We used suture anchors to attach the graft medially to the glenoid superior tubercle and laterally to the greater tuberosity. We added side-to-side sutures between the graft and infraspinatus tendon and between the graft and residual anterior supraspinatus/subscapularis tendon to improve force coupling. Physical examination, radiography, and magnetic resonance imaging (MRI) were performed before surgery; at 3, 6, and 12 months after surgery; and yearly thereafter. Average follow-up was 34.1 months (24 to 51 months) after surgery. RESULTS: Mean active elevation increased significantly from 84° to 148° (P < .001) and external rotation increased from 26° to 40° (P < .01). Acromiohumeral distance (AHD) increased from 4.6 ± 2.2 mm preoperatively to 8.7 ± 2.6 mm postoperatively (P < .0001). There were no cases of progression of osteoarthritis or rotator cuff muscle atrophy. Twenty patients (83.3%) had no graft tear or tendon retear during follow-up (24 to 51 months). The American Shoulder and Elbow Surgeons (ASES) score improved from 23.5 to 92.9 points (P < .0001). CONCLUSIONS: ASCR restored superior glenohumeral stability and function of the shoulder joint with irreparable rotator cuff tears. Our results suggest that this reconstruction technique is a reliable and useful alternative treatment for irreparable rotator cuff tears. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Effect of scapular orientation on shoulder internal impingement in a cadaveric model of the cocking phase of throwing.

BACKGROUND: Although deviations in scapular orientation are thought to predispose to shoulder injuries in throwing athletes, the biomechanical mechanism underlying shoulder injuries in throwing athletes with an altered scapular orientation remains unclear. METHODS: Seven fresh-frozen cadaveric shoulders were evaluated at 90° of abduction, with the humerus externally rotated from 90° to the maximum angle, to simulate the late cocking phase of the throwing motion. Loads were applied to the deltoid, pectoralis major, latissimus dorsi, teres major, and all rotator cuff muscles. Contact pressure in the glenohumeral joint was measured with use of a pressure sensor. The area of internal impingement was calculated on the basis of three-dimensional position data. Glenohumeral contact pressure and the area of impingement were compared between 20°, 30°, and 40° of internal scapular rotation; between 20°, 30°, and 40° of upward scapular rotation; and between 0° and 10° of anterior scapular tilt. Data were analyzed with use of repeated-measures analysis of variance with the Tukey post hoc test. RESULTS: Contact pressure was at its maximum in the posterior aspect of the glenohumeral joint. The glenohumeral contact pressure and internal impingement area increased with increasing internal scapular rotation. The glenohumeral contact pressure at 40° of internal scapular rotation was significantly (43.4%) greater than that at 20° of internal scapular rotation (p < 0.01), and the impingement area at 40° of internal scapular rotation was significantly (43.1%) greater than that at 20° of internal scapular rotation (p < 0.05). Decreasing upward scapular rotation resulted in an increase in internal impingement area. The internal impingement area at 40° of upward motion was 38.1% less than that at 20° of upward rotation (p < 0.001) and 28.9% less than that at 30° of upward rotation (p < 0.01). CONCLUSIONS: Increasing internal scapular rotation and decreasing upward scapular rotation significantly increase glenohumeral contact pressure and the area of impingement of the rotator cuff tendon between the greater tuberosity and glenoid during simulated throwing motion.

Superior capsule reconstruction to restore superior stability in irreparable rotator cuff tears: a biomechanical cadaveric study.

BACKGROUND: There have been many clinical reports of patch graft surgery for irreparable rotator cuff tears. However, the retear rate of the patch graft is relatively high because of the lack of superior stability, causing subacromial abrasions. PURPOSE: To compare superior stability among 3 types of patch grafting for simulated irreparable rotator cuff tears. STUDY DESIGN: Controlled laboratory study. METHODS: Eight cadaveric shoulders were tested in a custom shoulder testing system. Superior translation of the humerus, subacromial contact pressure, and glenohumeral joint force were quantified in the following 5 conditions: (1) when the rotator cuff was intact, (2) after cutting the supraspinatus tendon, (3) after the patch graft to reconstruct the supraspinatus tendon, (4) after the patch graft to reconstruct the superior capsule, and (5) after the patch graft to reconstruct both the supraspinatus tendon and superior capsule. While the graft was sutured to the torn tendon in condition 3, the graft was attached to the superior glenoid in condition 4. RESULTS: Compared with values for intact rotator cuffs, cutting the supraspinatus tendon significantly increased superior translation (P < .05), significantly increased subacromial contact pressure (P < .05), and significantly decreased glenohumeral compression force (P < .05). Superior translation was restored partially after the supraspinatus tendon patch graft and restored fully after the superior capsule patch graft and after both patch grafts. All patch grafts fully restored the subacromial contact pressure (P < .05) but did not alter the glenohumeral joint force. CONCLUSION: When patch graft surgery is chosen for irreparable rotator cuff tears, the graft should be attached medially to the superior glenoid and laterally to the greater tuberosity to restore superior stability of the humeral head. CLINICAL RELEVANCE: The superior capsule patch graft completely restored superior stability of the glenohumeral joint, while patch grafting to the supraspinatus tendon partially restored superior translation.

A new manual method for assessing elbow valgus laxity.

BACKGROUND: A screening of ulnar collateral ligament insufficiency is required for overhead throwers, since secondary pathologic changes result from an increased elbow valgus laxity. We developed a new manual method for assessing elbow valgus laxity and investigated the reliability of this method and its correlation with ultrasonographic assessment. METHODS: We defined elbow valgus laxity as the difference between the shoulder external rotation angle (ER angle) measured with the elbow in 90 degrees flexion and that measured with the elbow in extension because ER angle measured with the elbow in 90 degrees flexion includes elbow valgus laxity and ER angle with the elbow in extension does not include it. ER angle measurement with the elbow in extension involved the use of a custom arm holder. Three examiners each measured elbow valgus laxity by the new method in 5 healthy volunteers. Intraobserver and interobserver reliability was evaluated by calculating the intraclass correlation coefficient. We then assessed 19 high-school baseball players with no complaints of shoulder or elbow pain. Elbow ultrasonography was performed with a 10-MHz linear transducer with the elbow in 90 degrees flexion, and the forearm in the neutral position, and the width of the medial joint space at the level of the anterior bundle was measured. Elbow valgus laxity assessed by ultrasonography was defined as the difference between the medial joint space width with gravity stress and that without gravity stress. Increased elbow valgus laxity assessed by both our method and ultrasonography was defined as the difference between the laxity of the elbow on the throwing side and that on the contralateral side. Pearson's correlation coefficient (r) was calculated to evaluate the relationship between increased elbow valgus laxity obtained by our manual method and that by ultrasonography. RESULTS: Intraobserver reliability ranged from 0.92 to 0.98, and interobserver reliability was 0.70. The increased elbow valgus laxity assessed by our method was significantly correlated with that assessed by ultrasonographic assessment (P = 0.019, r = 0.53). CONCLUSIONS: Elbow valgus laxity can be assessed by our method. This method may be useful for screening for insufficiency of the ulnar collateral ligament.

In vivo degradation and new bone formation of calcium phosphate cement-gelatin powder composite related to macroporosity after in situ gelatin degradation.

Calcium phosphate cement (CPC) is reported to have excellent biocompatibility and osteoconductivity. However, its biodegradability must be improved to promote bone regeneration. We have mixed gelatin powder with CPC to create a composite containing macropores with interconnectivity. Sixty rabbits were grouped as follows: 85 wt% CPC to 15 wt% gelatin powder (C15), 90 wt% CPC to 10 wt% gelatin powder (C10), 100 wt% CPC (C0) as control group and Sham group. Trabecular bone defects of distal femurs were made and implanted with the composites. The femurs were harvested for histomorphometry at 4, 12, 24 weeks after implantation, and mechanical testing at 3 days, 1, 4, 12, 24 weeks. Compared with C0, X-ray and micro-CT results of the composites revealed a progressive increase in the amount of CPC-gelatin powder composite which was replaced by trabeculae. New bone area increased from 3.8 to 18% in C10, and 4.2 to 22% in C15, residual composite area decreased from 65 to 31% in C10, and 70 to 20% in C15. The compressive strength of C15 was 9.2 MPa, which was inferior to 14.6 MPa (normal cancellous bone), but was 27.4 MPa in C10 at 1 week. Further improvement of this composite may make a suitable scaffold for bone regeneration.

Anterior cruciate ligament changes in the human knee joint in aging and osteoarthritis.

OBJECTIVE: The development and patterns of spontaneous age-related changes in the anterior cruciate ligament (ACL) and their relationship to articular cartilage degeneration are not well characterized. This study was undertaken to investigate the types and temporal sequence of age-related ACL changes and to determine their correlation with cartilage lesion patterns at all stages of osteoarthritis (OA) development in human knee joints without prior joint trauma. METHODS: Human knee joints (n = 120 from 65 donors ages 23-92) were obtained at autopsy, and ACLs and cartilage were graded macroscopically and histologically. Inflammation surrounding the ACL was assessed separately. RESULTS: Histologic ACL substance scores and ligament sheath inflammation scores increased with age. Collagen fiber disorganization was the earliest and most prevalent change. The severity of mucoid degeneration and chondroid metaplasia in the ACL increased with the development of cartilage lesions. A correlation between ACL degeneration and cartilage degeneration was observed, especially in the medial compartment of the knee joint. CONCLUSION: Our findings indicate that ACL degeneration is highly prevalent in knees with cartilage defects and may even precede cartilage changes. Hence, ACL deficiencies may not only be important in posttraumatic OA, but may also be a feature associated with knee OA pathogenesis in general.

Hallux valgus angle as a predictor of recurrence following proximal metatarsal osteotomy.

BACKGROUND: Postoperative recurrence of hallux valgus is a common complication. We hypothesized that patients who are at higher risk for recurrence of hallux valgus following a proximal metatarsal osteotomy could be recognized preoperatively and at the early follow-up on the basis of their radiographic evaluation. The purpose of this study was to clarify the relationship between the hallux valgus angle, intermetatarsal angle, and recurrence of hallux valgus. METHODS: We performed a case-control study of patients treated with a proximal metatarsal osteotomy for hallux valgus. Dorsoplantar weight-bearing radiographs of 72 feet were assessed preoperatively, at the early follow-up interval (mean 10 weeks), and at the most recent follow-up interval (mean 33 months). RESULTS: The rate of recurrence was 13.9% (ten feet). Risk factors for recurrence were preoperative hallux valgus angle >40° [odds ratio (OR) = 5.1; 95% confidence interval (CI) 1.3-20.8]. Decreased risks of hallux valgus recurrence were a hallux valgus angle ≤ 15° (OR = 0.036, 95% CI = 0.0056-0.24, p = 0.0005), and an intermetatarsal angle <10° (OR = 0.083, 95% CI = 0.015-0.46, p = 0.0075) at the time of the early follow-up with the numbers available. CONCLUSIONS: Our radiographic results indicated that a preoperative hallux valgus angle >40° can be a risk factor for hallux valgus recurrence. Decreased risk factors for recurrence included hallux valgus angle ≤ 15° and an intermetatarsal angle <10° at the early follow-up. These risk factors may be helpful for modifying surgical procedures, improving surgical outcome, and predicting hallux valgus recurrence.

Functional and structural outcomes of single-row versus double-row versus combined double-row and suture-bridge repair for rotator cuff tears.

BACKGROUND: Although previous biomechanical research has demonstrated the superiority of the suture-bridge rotator cuff repair over double-row repair from a mechanical point of view, no articles have described the structural and functional outcomes of this type of procedure. HYPOTHESIS: The structural and functional outcomes after arthroscopic rotator cuff repair may be different between the single-row, double-row, and combined double-row and suture-bridge (compression double-row) techniques. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: There were 206 shoulders in 201 patients with full-thickness rotator cuff tears that underwent arthroscopic rotator cuff repair. Eleven patients were lost to follow-up. Sixty-five shoulders were repaired using the single-row, 23 shoulders using the double-row, and 107 shoulders using the compression double-row techniques. Clinical outcomes were evaluated at an average of 38.5 months (range, 24-74 months) after rotator cuff repair. Postoperative cuff integrity was determined using Sugaya's classification of magnetic resonance imaging (MRI). RESULTS: The retear rates after arthroscopic rotator cuff repair were 10.8%, 26.1%, and 4.7%, respectively, for the single-row, double-row, and compression double-row techniques. In the subcategory of large and massive rotator cuff tears, the retear rate in the compression double-row group (3 of 40 shoulders, 7.5%) was significantly less than those in the single-row group (5 of 8 shoulders, 62.5%, P < .001) and the double-row group (5 of 12 shoulders, 41.7%, P < .01). Postoperative clinical outcomes in patients with a retear were significantly lower than those in patients without a retear for all 3 techniques. CONCLUSION: The additional suture bridges decreased the retear rate for large and massive tears. The combination of the double-row and suture-bridge techniques, which had the lowest rate of postoperative retear, is an effective option for arthroscopic repair of the rotator cuff tendons because the postoperative functional outcome in patients with a retear is inferior to that without retear.

Effect of shoulder abduction angle on biomechanical properties of the repaired rotator cuff tendons with 3 types of double-row technique.

BACKGROUND: After rotator cuff repair, the shoulder is immobilized in various abduction positions. However, there is no consensus on the proper abduction angle. PURPOSE: To assess the effect of shoulder abduction angle on the biomechanical properties of the repaired rotator cuff tendons among 3 types of double-row techniques. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty-two fresh-frozen porcine shoulders were used. A simulated rotator cuff tear was repaired by 1 of 3 double-row techniques: conventional double-row repair, transosseous-equivalent repair, and a combination of conventional double-row and bridging sutures (compression double-row repair). Each specimen underwent cyclic testing followed by tensile testing to failure at a simulated shoulder abduction angle of 0° or 40° on a material testing machine. Gap formation and failure loads were measured. RESULTS: Gap formation in conventional double-row repair at 0° (1.2 ± 0.5 mm) was significantly greater than that at 40° (0.5 ± 0.3mm, P = .01). The yield and ultimate failure loads for conventional double-row repair at 40° were significantly larger than those at 0° (P < .01), whereas those for transosseous-equivalent repair (P < .01) and compression double-row repair (P < .0001) at 0° were significantly larger than those at 40°. The failure load for compression double-row repair was the greatest among the 3 double-row techniques at both 0° and 40° of abduction. CONCLUSION: Bridging sutures have a greater effect on the biomechanical properties of the repaired rotator cuff tendon at a low abduction angle, and the conventional double-row technique has a greater effect at a high abduction angle. CLINICAL RELEVANCE: Proper abduction position after rotator cuff repair differs between conventional double-row repair and transosseous-equivalent repair. The authors recommend the use of the combined technique of conventional double-row and bridging sutures to obtain better biomechanical properties at both low and high abduction angles.

Extracellular sulfatases support cartilage homeostasis by regulating BMP and FGF signaling pathways.

The balance between anabolic and catabolic signaling pathways is critical in maintaining cartilage homeostasis and its disturbance contributes to joint diseases such as osteoarthritis (OA). A unique mechanism that modulates the activity of cell signaling pathways is controlled by extracellular heparan endosulfatases Sulf-1 and Sulf-2 (Sulfs) that are overexpressed in OA cartilage. This study addressed the role of Sulfs in cartilage homeostasis and in regulating bone morphogenetic protein (BMP)/Smad and fibroblast growth factor (FGF)/Erk signaling in articular cartilage. Spontaneous cartilage degeneration and surgically induced OA were significantly more severe in Sulf-1(-/-) and Sulf-2(-/-) mice compared with wild-type mice. MMP-13, ADAMTS-5, and the BMP antagonist noggin were elevated whereas col2a1 and aggrecan were reduced in cartilage and chondrocytes from Sulf(-/-) mice. Articular cartilage and cultured chondrocytes from Sulf(-/-) mice showed reduced Smad1 protein expression and Smad1/5 phosphorylation, whereas Erk1/2 phosphorylation was increased. In human chondrocytes, Sulfs siRNA reduced Smad phosphorylation but enhanced FGF-2-induced Erk1/2 signaling. These findings suggest that Sulfs simultaneously enhance BMP but inhibit FGF signaling in chondrocytes and maintain cartilage homeostasis. Approaches to correct abnormal Sulf expression have the potential to protect against cartilage degradation and promote cartilage repair in OA.

Altered expression of sodium channel distribution in the dorsal root ganglion after gradual elongation of rat sciatic nerves.

To elucidate the pathophysiological mechanisms underlying chronic nerve-stretch injury, we gradually lengthened rat femurs by 15 mm at the rate of 0.5 mm/day (group L, n = 13). The control groups comprised sham-operated (group S, n = 10) and naive (group N, n = 8) rats. Immediately after the lengthening, we performed a conduction study on their sciatic nerves and harvested samples. Electrophysiological and histological analyses showed mild conduction slowing and axonal degeneration of unmyelinated fibers in group L rats. Altered mRNA expression of the voltage-gated sodium channels in the dorsal root ganglion was also observed. Tetrodotoxin-resistant (TTX-R) sodium-channel Nav1.8 mRNA expression was significantly decreased and TTX-R sodium-channel Nav1.9 mRNA expression showed a tendency to decrease when compared with the mRNA expressions in the control groups. However, tetrodotoxin-sensitive (TTX-S) sodium-channel Nav1.3 mRNA expression remained unaltered. The immunohistochemical alteration of Nav1.8 protein expression was parallel to the results of the mRNA expression. Previous studies involving neuropathic states have suggested that pain/paresthesia is modulated by a subset of sodium channels, including downregulation and/or upregulation of TTX-R and TTX-S sodium channels, respectively. Our findings indicate that Nav1.8 downregulation may be one of the pathophysiological mechanisms involved in limb lengthening-induced neuropathy.

Tissue neogenesis and STRO-1 expression in immature and mature articular cartilage.

This study determined the potential for neotissue formation and the role of STRO-1+ cells in immature versus mature articular cartilage. Cartilage explants from immature and mature bovine knee joints were cultured for up to 12 weeks and stained with safranin-O, for type II collagen and STRO-1. Bovine chondrocyte pellet cultures and murine knee joints at the age of 2 weeks and 3 months, and surgically injured cartilage, were analyzed for changes in STRO-1 expression patterns. Results show that immature explants contained more STRO-1+ cells than mature explants. After 8 weeks in culture, immature explants showed STRO-1+ cell proliferation and newly formed tissue, which contained glycosaminoglycan and type II collagen. Mature cartilage explants showed only minimal cell expansion and neotissue formation. Pellet cultures with chondrocytes from immature cartilage showed increased glycosaminoglycan synthesis and STRO-1+ staining, as compared to pellets with mature chondrocytes. The frequency of STRO-1+ cells in murine knee joints significantly declined with joint maturation. Following surgical injury, immature explants had higher potential for tissue repair than mature explants. In conclusion, these findings suggest that the high percentage of STRO-1+ cells in immature cartilage changes with joint maturation. STRO-1+ cells have the potential to form new cartilage spontaneously and after tissue injury.

Excessive glenohumeral horizontal abduction as occurs during the late cocking phase of the throwing motion can be critical for internal impingement.

BACKGROUND: The objective of this study was to determine the effects of increased horizontal abduction with maximum external rotation, as occurs during the late cocking phase of throwing motion, on shoulder internal impingement. HYPOTHESIS: An increase in glenohumeral horizontal abduction will cause overlap of the rotator cuff insertion with respect to the glenoid and increase pressure between the supraspinatus and infraspinatus tendon insertions on the greater tuberosity and the glenoid. STUDY DESIGN: Controlled laboratory study. METHODS: Eight cadaveric shoulders were tested with a custom shoulder testing system with the specimens in 60 degrees of glenohumeral abduction and maximum external rotation. The amount of internal impingement was evaluated by assessing the location of the supraspinatus and infraspinatus articular insertions on the greater tuberosity relative to the glenoid using a MicroScribe 3DLX. Pressure in the posterior-superior quadrant of the glenoid was measured using Fuji prescale film. Data were obtained with the humerus in the scapular plane and 15 degrees , 30 degrees , and 45 degrees of horizontal abduction from the scapular plane. RESULTS: At 30 degrees and 45 degrees of horizontal abduction, the articular margin of the supraspinatus and infraspinatus tendons was anterior to the posterior edge of the glenoid and less than 2 mm from the glenoid rim in the lateral direction; the contact pressure was also greater than that found in the scapular plane and 15 degrees of horizontal abduction. Conclusion Horizontal abduction beyond the coronal plane increased the amount of overlap and contact pressure between the supraspinatus and infraspinatus tendons and glenoid. CLINICAL RELEVANCE: Excessive glenohumeral horizontal abduction beyond the coronal plane may cause internal impingement, which may lead to rotator cuff tears and superior labral anterior to posterior (SLAP) lesions.

Adjacent vertebral body fracture following vertebroplasty with polymethylmethacrylate or calcium phosphate cement: biomechanical evaluation of the cadaveric spine.

STUDY DESIGN: A biomechanical study using human cadaveric thoracolumbar spinal columns. OBJECTIVE: To compare the effect of treatment by vertebroplasty (VP) with polymethylmethacrylate cement and VP with calcium phosphate cement on the creation of adjacent vertebral body fracture following VP. SUMMARY OF BACKGROUND DATA: Adjacent vertebral body fractures have been reported as a complication following VP. METHODS: Twenty-four spinal columns (T10-L2) from human cadavers were subjected to dual energy radiograph absorptiometry to assess bone mineral density. They were divided into the P group and C group, and experimental vertebral compression fractures were created at T12 vertebrae. T12 vertebrae were augmented with polymethylmethacrylate and calcium phosphate cement in the P group and C group, respectively. Each spinal column was compressed until a new fracture occurred at any vertebra, and the location of newly fractured vertebra and failure load was investigated. RESULTS: There was no significant difference in bone mineral density at each level within each group. In the P group, a new fracture occurred at T10 in 2 specimens, T11 in 8, and L1 in 2. In the C group, it occurred at T10 in 1 specimen, T11 in 2, L1 in 1, and T12 (treated vertebra) in 8. The failure loads of the spinal column were 1774.8+/-672.3 N and 1501.2+/-556.5 N in the P group and C group, respectively. There was no significant difference in the failure load of the spinal column between each group. CONCLUSION: New vertebral fractures occurred at the vertebra adjacent to augmented vertebrae in the P group and in the augmented vertebrae in the C group. The difference in the fractured site may be because of the difference in strength between the 2 bone filler materials. Therefore, the strength of bone filler materials is considered a risk factor in developing adjacent vertebral body fractures after VP.

Effect of rotator cuff muscle imbalance on forceful internal impingement and peel-back of the superior labrum: a cadaveric study.

BACKGROUND: Throwing athletes with shoulder pain have been shown to have decreased rotator cuff muscle strength. Shoulder internal impingement and labral peel-back mechanism, as may occur during the late cocking phase of throwing motion, are thought to cause rotator cuff injury and type II superior labrum anterior and posterior lesions. Therefore, the objective of this study was to assess the effect of rotator cuff muscle force on internal impingement and the peel-back of the superior labrum by quantifying maximum external rotation, glenohumeral contact pressure, and position of the cuff insertion relative to the glenoid. HYPOTHESIS: A change in rotator cuff muscle force will lead to increased external rotation, glenohumeral contact pressure, and overlap of the cuff insertion relative to the glenoid. STUDY DESIGN: Controlled laboratory study. METHODS: Eight fresh-frozen cadaveric shoulders were tested at the simulated late cocking position. Glenohumeral contact pressure, location of the cuff insertion relative to the glenoid, and maximum humeral external rotation angle were measured. The forces of the supraspinatus, subscapularis, and infraspinatus muscles were determined based on published clinical electromyographic data. To assess the effect of cuff muscle imbalance, each muscle force was varied. Horizontal abduction positions of 20 degrees , 30 degrees , and 40 degrees with respect to the scapular plane were tested. RESULTS: Decreased subscapularis strength resulted in a significant increase in maximum external rotation (P <.001) and increased glenohumeral contact pressure (P <.01). The cuff insertion overlapped the edge of the glenoid at 30 degrees and 40 degrees of horizontal abduction for all muscle loading conditions. CONCLUSION: Decreased subscapularis muscle strength in the position simulating the late cocking phase of throwing motion results in increased maximum external rotation and also increased glenohumeral contact pressure. CLINICAL RELEVANCE: Athletes with decreased subscapularis muscle strength, such as fatigue with repetitive throwing, may be more susceptible to rotator cuff tears and type II superior labrum anterior and posterior lesions. Subscapularis muscle strengthening exercises may be beneficial for preventing these injuries.

Postoperative incomplete reduction of the sesamoids as a risk factor for recurrence of hallux valgus.

BACKGROUND: It is unknown whether postoperative incomplete reduction of the sesamoids is a risk factor for the recurrence of hallux valgus. The purpose of the present study was to clarify the relationship between the postoperative relative sesamoid position and the recurrence of hallux valgus. METHODS: Dorsoplantar weight-bearing radiographs of sixty normal feet (the control group) and sixty-five feet with hallux valgus (the hallux valgus group) in a study of adult women were reviewed. The feet in the hallux valgus group were treated with a proximal metatarsal osteotomy, and the radiographs were assessed preoperatively, at the early follow-up interval (at a mean of 3.1 months), and at the most recent follow-up interval (at a mean of forty-five months). The position of the medial sesamoid was classified with a grading system ranging from I through VII as described by Hardy and Clapham. In the feet with hallux valgus, we defined a grade of IV or less as the normal position of the medial sesamoid (the normal-position group) and grade V or greater as lateral displacement of the sesamoid (the displacement group). RESULTS: Fifty feet (83%) in the control group were classified as grade IV or less and ten, as grade V. All feet in the hallux valgus group were classified as grade V or greater preoperatively, forty-eight feet (74%) were classified as grade IV or less at the early follow-up evaluation, and forty-two feet (65%) were classified as grade IV or less at the most recent follow-up evaluation. The average hallux valgus angle in the hallux valgus group was 38.3 degrees (range, 25 degrees to 60 degrees ) preoperatively, 11.9 degrees (range, 4 degrees to 28 degrees ) at the time of the early follow-up, and 13.9 degrees (range, 0 degrees to 33 degrees ) at the time of the most recent follow-up. There was no significant difference in the average hallux valgus angle between the early and most recent follow-up evaluations in the feet that were considered to be in the normal-position group at the time of the early follow-up (p = 0.084). In the feet that were considered to be in the displacement group at the time of the early follow-up, the average hallux valgus angle at the time of the most recent follow-up was significantly greater than that at the time of the early follow-up (19.5 degrees +/- 8.4 degrees compared with 15.0 degrees +/- 5.8 degrees ) (p = 0.0082). The feet that were in the displacement group at the time of the early follow-up had a greater risk of having recurrence of the hallux valgus at that time than did those in the normal-position group (odds ratio, 10.0; 95% confidence interval, 2.75 to 36.33). CONCLUSIONS: Postoperative incomplete reduction of the sesamoids can be a risk factor for the recurrence of hallux valgus. The identification of incomplete reduction of the sesamoids intraoperatively may allow modification of surgical procedures and improvement of the surgical results.