Association of Traumatic and Atraumatic Posterior Shoulder Instability With Glenoid Retroversion and Outcomes After Arthroscopic Capsulolabral Repair.

PURPOSE: To compare glenoid retroversion and functional outcomes between patients with traumatic onset of posterior shoulder instability (PSI) and patients with atraumatic onset of PSI. METHODS: Patients with PSI who underwent arthroscopic posterior capsulolabral anchor repair, were active in sports, and had undergone surgery a minimum of 2 years earlier were included. Traumatic onset was defined as PSI that occurred after a trauma with the shoulder in adduction, flexion, and internal rotation in patients with no history of instability. Subjective evaluations were obtained with the American Shoulder and Elbow Surgeons (ASES); Quick Disabilities of the Arm, Shoulder and Hand; Single Assessment Numeric Evaluation (SANE); and Short Form 12 Physical Component Summary scores preoperatively and after a minimum 2-year follow-up postoperatively. Additional questions assessed return to sport and shoulder stability. Glenoid version was measured with a 2-dimensional glenoid vault method on magnetic resonance imaging. RESULTS: A total of 41 shoulders in 38 patients were eligible for inclusion (3 female and 35 male patients; mean age, 27.6 years; age range, 13 to 66 years). Three patients refused participation, and 2 patients required subsequent surgery for failure. Postoperative outcomes were available for 32 of the remaining 36 shoulders (89%) with a mean follow-up of 4.1 years (range, 2.0 to 7.8 years; 20 atraumatic and 12 traumatic). The ASES score improved significantly in both groups (P < .03), whereas the SANE; Quick Disabilities of the Arm, Shoulder and Hand; and Short Form 12 Physical Component Summary scores only significantly improved for patients with traumatic PSI (P < .02). Baseline score-adjusted comparison between groups showed that the postoperative median ASES scores (atraumatic, 95.8; traumatic, 99.9) and SANE scores (atraumatic, 86.5; traumatic, 98.0) were significantly more improved in patients with traumatic PSI (P = .01 and P = .012, respectively). Atraumatic PSI was associated with significantly higher glenoid retroversion (-21.8° ± 4.2° vs -17.7° ± 5.5°, P = .032). There was no significant difference regarding return to sport (P = .375) or postoperative re-dislocations (P = .99) between the groups. CONCLUSIONS: Atraumatic onset of PSI was associated with higher degrees of glenoid retroversion and less favorable functional outcomes of arthroscopic posterior capsulolabral anchor repair than traumatic PSI. LEVEL OF EVIDENCE: Level III, retrospective case-control study.

Impact of Arthroscopic Lateral Acromioplasty on the Mechanical and Structural Integrity of the Lateral Deltoid Origin: A Cadaveric Study.

PURPOSE: To determine whether a 5-mm and/or 10-mm arthroscopic lateral acromioplasty (ALA) would weaken the structural and mechanical integrity of the lateral deltoid. METHODS: The acromion and lateral deltoid origin were harvested from 15 pairs (n = 30) of fresh-frozen human cadaveric shoulder specimens. One side of each specimen pair (left or right) was randomly assigned to either a 5-mm (n = 7) or 10-mm (n = 8) ALA group, and the contralateral sides (n = 15) were used as matched controls. Acromion thickness and width were measured pre- and postoperatively. After ALA, specimens were inspected for damage to the lateral deltoid origin. Each specimen was secured within a dynamic testing machine, and the deltoid muscle was pulled to failure. Statistical analysis was performed to determine whether ALA reduced the lateral deltoid's failure load. RESULTS: There was no significant difference in failure load between the 5-mm ALA group (661 ± 207 N) and its matched control group (744 ± 212 N; mean difference = 83 N; 95% confidence interval [CI], -91 to 258; P = .285) nor between the 10-mm ALA group (544 ± 210 N) and its matched control group (598 ± 157 N; mean difference = 54 N; 95% CI, -141 to 250; P = .532). There was no correlation found between the amount of bone resected (measured by percent thickness and width of the acromion after ALA) and the failure load of the deltoid. Visual evaluation of the acromion after ALA revealed the lateral deltoid origin had no damage in any case. CONCLUSIONS: ALA did not weaken the structural or mechanical integrity of the lateral deltoid origin. Neither a 5-mm nor a 10-mm ALA significantly reduced the deltoid's failure load. The lateral deltoid origin was not macroscopically damaged in any case. CLINICAL RELEVANCE: ALA can be performed without the potential risk of macroscopically damaging the lateral deltoid origin or reducing its failure load.

The effect of bone morphogenetic protein-2 injection at different time points on intervertebral disk degeneration in a rat tail model.

STUDY DESIGN: Prospective in vivo rat tail model of disk degeneration comparing the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) injection over various time points and grades of degeneration. OBJECTIVE: To evaluate the effect of timing and disk grade on rhBMP-2 injection in a rat tail model of disk degeneration. SUMMARY OF BACKGROUND DATA: rhBMP-2 stimulates the proliferation of intervertebral disk cells and the secretion of extracellular matrix. However, few in vivo studies have demonstrated whether rhBMP-2 also improves disk degeneration and the severity of disk degeneration beyond which disks cannot be recovered by rhBMP-2 treatment. METHODS: Two coccygeal disks of each rodent subject were punctured percutaneously using an 18 G needle. At 4 weeks after the puncture, disks demonstrating induced degeneration were divided into 3 groups. Groups 1, 2, and 3 were treated with 7.5 µg rhBMP-2 or phosphate buffered saline by injection into the disk at 4, 6, and 8 weeks postpuncture, respectively. Plain radiographs and magnetic resonance images (MRIs) were obtained on the day of puncture and every 2 weeks thereafter until sacrifice. At 6 weeks after injection, each group was killed and examined with histologic and immunohistochemical analysis. RESULTS: According to MRI disk grade evaluation of the degenerative disk, rhBMP-2 significantly improved degeneration grade in group 1 at 2 weeks after injection. According to radiographic disk height index, groups 1 and 2 showed a trend toward improvement at 2 weeks after rhBMP-2 injection. Chondrogenic differentiation was noted on immunohistochemical staining of many disks treated with rhBMP-2. CONCLUSIONS: rhBMP-2 injection of degenerated disks at 4 weeks postpuncture induced a transient improvement in disk grade on MRI and stimulated chondrogenic differentiation. These data suggest rhBMP-2 as a potential therapy for degenerative disk disease.

Demographic analysis of open and arthroscopic distal clavicle excision in a private insurance database.

PURPOSE: The purpose of this study was to evaluate and quantify the demographic characteristics of patients undergoing open and arthroscopic distal clavicle excision (DCE) in the United States while also describing changes in practice patterns over time. METHODS: Patients who underwent DCE from 2004 to 2009 were identified by Current Procedural Terminology (CPT) codes in a national database of orthopaedic insurance records. The year of procedure, age, sex, geographic region, and concomitant rotator cuff repair or subacromial decompression (SAD) were recorded for each patient. Results were reported as the incidence of procedures identified per 10,000 patients searched in the database. RESULTS: Between 2004 and 2009, 73,231 DCEs were performed; 74% were arthroscopic and 26% were open. The incidence of arthroscopic DCE increased from 37.8 in 2004 to 58.5 in 2009 (P < .001), whereas the incidence of open DCE decreased from 21.1 in 2004 to 14.1 in 2009 (P < .001). Sixty-one percent of DCEs were performed in men (P < .001). Women were more likely to undergo an arthroscopic procedure (P < .001). Arthroscopic DCE was most common in patients aged 50 to 59 years (P < .001). Open DCE was most common in patients aged 60 to 69 years (P < .001). Open rotator cuff repair and SAD were concomitantly performed in 38% and 23% of open DCEs, respectively. Arthroscopic rotator cuff repair and SAD were concomitantly performed in 33% and 95% arthroscopic DCEs, respectively. CONCLUSIONS: This analysis of DCE using a private insurance database shows that arthroscopic DCEs progressively increased, whereas open DCEs concomitantly decreased between 2004 and 2009. The majority of DCEs were performed in men between the ages of 50 and 59 years. Both arthroscopic and open DCEs are frequently performed in conjunction with rotator cuff repair or SAD. LEVEL OF EVIDENCE: Level IV, cross-sectional study.

Arthroscopic versus open shoulder stabilization: current practice patterns in the United States.

PURPOSE: The purpose of this study was to investigate current trends in arthroscopic and open shoulder stabilization in the United States. METHODS: Patients who underwent arthroscopic shoulder stabilization (Current Procedural Terminology code 29806) or open stabilization (Current Procedural Terminology codes 23455 [open Bankart repair], 23460 [anterior bone block], and 23462 [coracoid transfer]) were identified using a national database of insurance billing records during the years 2004 through 2009. Demographic data were recorded for each patient. RESULTS: From 2004 through 2009, there were 23,096 cases of shoulder stabilization, of which 84% (19,337) were arthroscopic and 16% (3,759) were open procedures. There were 17,241 male patients (75%) and 5,855 female patients (25%). The incidence of arthroscopic shoulder stabilization nearly doubled during the period studied, increasing from 11.8 cases for every 10,000 patients in 2004 to 22.9 cases for every 10,000 patients in 2009. The percentage of arthroscopic stabilizations increased from 71% of stabilization procedures in 2004 to 89% in 2009, whereas the percentage of open stabilizations decreased from 29% in 2004 to 11% in 2009 (P < .0001). Among open procedures, a significant decline in the incidence of open Bankart repair was observed, from 4.5 cases for every 10,000 patients in 2004 to 2.2 cases for every 10,000 patients in 2009 (P < .0001), whereas the performance of open coracoid transfer increased from 0.17 cases per 10,000 patients in 2004 to 0.40 cases per 10,000 patients in 2009 (P < .0001). For both arthroscopic and open stabilization, the group aged 10 to 19 years had the highest rate of surgery (29%), followed by the group aged 20 to 29 years (25%). CONCLUSIONS: The current data indicate that arthroscopic stabilization is performed in nearly 90% of shoulder stabilization surgeries and nearly doubled in incidence from 2004 to 2009 in the United States. Additional research is needed to further investigate the long-term clinical outcomes of this practice pattern. LEVEL OF EVIDENCE: Level IV, retrospective database review.

Trends in the surgical treatment of articular cartilage defects of the knee in the United States.

PURPOSE: The purpose of this study was to evaluate trends in surgical treatment of articular cartilage defects of the knee in the United States. METHODS: The current procedural terminology (CPT) billing codes of patients undergoing articular cartilage procedures of the knee were searched using the PearlDiver Patient Record Database, a national database of insurance billing records. The CPT codes for chondroplasty, microfracture, osteochondral autograft, osteochondral allograft, and autologous chondrocyte implantation (ACI) were searched. RESULTS: A total of 163,448 articular cartilage procedures of the knee were identified over a 6-year period. Microfracture and chondroplasty accounted for over 98% of cases. There was no significant change in the incidence of cartilage procedures noted from 2004 (1.27 cases per 10,000 patients) to 2009 (1.53 cases per 10,000 patients) (p = 0.06). All procedures were performed more commonly in males (p < 0.001). This gender difference was smallest in patients undergoing chondroplasty (51 % males and 49% females) and greatest for open osteochondral allograft (61% males and 39% females). Chondroplasty and microfracture were most commonly performed in patients aged 40-59, while all other procedures were performed most frequently in patients <40 years old (p < 0.001). CONCLUSIONS: Articular cartilage lesions of the knee are most commonly treated with microfracture or chondroplasty in the United States. Chondroplasty and microfracture were most often performed in middle-aged patients, whereas osteochondral autograft, allograft, and ACI were performed in younger patients, and more frequently in males. LEVEL OF EVIDENCE: Cross-sectional study, Level IV.

Analysis of rotator cuff repair trends in a large private insurance population.

PURPOSE: The purpose of this study was to identify current trends in open and arthroscopic surgical treatment of rotator cuff tears across sex, age, and region in the United States. METHODS: Using the PearlDiver Patient Record Database (PearlDiver, Fort Wayne, IN), a publicly available national database of insurance records, patients who underwent rotator cuff repair from 2004 through 2009 were identified. The number of open (CPT codes 23410, 23412, 23420) and arthroscopic (CPT code 29827) rotator cuff repairs were quantified in isolation and in combination with acromioplasty (CPT codes 23415, 29826). The type of procedure, date, sex, and region of the country was identified for each patient. Trend tests (χ(2) and Cochran-Armitage) were used to determine statistical significance. RESULTS: There were 151,866 rotator cuff repair procedures identified in the database from 2004 through 2009, which represented an incidence of 13.6 for every 1,000 patients assigned an orthopaedic International Classification of Diseases, Ninth Revision (ICD-9) or Current Procedural Terminology (CPT) code. Male patients accounted for 60% of the repairs and female patients for 40%. There were 98,174 arthroscopic cuff repairs (65%) and 53,692 open repairs (35%). The annual percentage of arthroscopic cases increased from 48.8% in 2004 to 74.3% in 2009, whereas the percentage of open cases decreased from 51.2% in 2004 to 25.7% in 2009 (P < .0001). Acromioplasty was also performed in 47.3% of cases, and the rate showed only a slight increase (from 46.6% to 47.8%) between 2004 and 2009 (P < .01). All regions of the United States showed similar surgical trends and trends for sex and age distributions. CONCLUSIONS: Our analysis shows that the majority of rotator cuff repairs in the United States are now performed arthroscopically (>74%) and there has been a recent steady decline in performance of open rotator cuff repair. Concomitant acromioplasty is performed approximately half the time, and this trend is increasing slightly. These findings were consistent across age, sex, and region in the United States. LEVEL OF EVIDENCE: IV, cross-sectional study.

Trends and demographics in hip arthroscopy in the United States.

PURPOSE: The purpose of this study was to evaluate the trends and report on the demographics of patients undergoing hip arthroscopy in the United States. METHODS: Patients who underwent hip arthroscopy from 2004 to 2009 were identified by searching Current Procedural Terminology codes in the PearlDiver Patient Records Database (PearlDiver Technologies, Fort Wayne, IN), a national database of orthopaedic insurance records. The year of procedure, age, gender, and region of the United States were recorded for each patient. Results were reported for each variable as the incidence of procedures identified per 10,000 patients searched in the database. RESULTS: In total, 3,447 cases of hip arthroscopy were identified between 2004 and 2009. The incidence of procedures increased significantly over the study period, from 1.20 cases per 10,000 patients in 2004 to 5.58 in 2009 (P < .001). Hip arthroscopy was performed most commonly in patients aged 20 to 39 years (P < .05), with an incidence of 4.45 cases in each age group. In contrast to other common arthroscopic procedures searched, no gender differences were observed, with a male-to-female ratio of 0.89 (P = .18). The greatest incidence of hip arthroscopy was observed in the Western region with an incidence of 5.24 cases identified compared with 2.94, 2.70, and 2.56 in the Northeast, Midwest, and South, respectively (P < .001). CONCLUSIONS: A 365% increase in the rate of hip arthroscopy was observed in the examined cohort of patients between 2004 and 2009. The majority of cases were performed in patients aged 20 to 39 years, with no difference in gender. The Western region of the United States was found to have a higher incidence of hip arthroscopy compared with the Midwest, South, and Northeast. LEVEL OF EVIDENCE: Level IV, cross-sectional study.

Kinetic magnetic resonance imaging analysis of lumbar segmental mobility in patients without significant spondylosis.

PURPOSE: The purpose of this study was to examine lumbar segmental mobility using kinetic magnetic resonance imaging (MRI) in patients with minimal lumbar spondylosis. METHODS: Mid-sagittal images of patients who underwent weight-bearing, multi-position kinetic MRI for symptomatic low back pain or radiculopathy were reviewed. Only patients with a Pfirrmann grade of I or II, indicating minimal disc disease, in all lumbar discs from L1-2 to L5-S1 were included for further analysis. Translational and angular motion was measured at each motion segment. RESULTS: The mean translational motion of the lumbar spine at each level was 1.38 mm at L1-L2, 1.41 mm at L2-L3, 1.14 mm at L3-L4, 1.10 mm at L4-L5 and 1.01 mm at L5-S1. Translational motion at L1-L2 and L2-L3 was significantly greater than L3-4, L4-L5 and L5-S1 levels (P < 0.007). The mean angular motion at each level was 7.34° at L1-L2, 8.56° at L2-L3, 8.34° at L3-L4, 8.87° at L4-L5, and 5.87° at L5-S1. The L5-S1 segment had significantly less angular motion when compared to all other levels (P < 0.006). The mean percentage contribution of each level to the total angular mobility of the lumbar spine was highest at L2-L3 (22.45 %) and least at L5/S1 (14.71 %) (P < 0.001). CONCLUSION: In the current study, we evaluated lumbar segmental mobility in patients without significant degenerative disc disease and found that translational motion was greatest in the proximal lumbar levels whereas angular motion was similar in the mid-lumbar levels but decreased at L1-L2 and L5-S1.

A Cadaveric Model Evaluating the Influence of Bony Anatomy and the Effectiveness of Partial Scapulectomy on Decompression of the Scapulothoracic Space in Snapping Scapula Syndrome.

BACKGROUND: Snapping scapula syndrome (SSS) is caused by bony and/or soft tissue impingement in the scapulothoracic articulation. Surgical resection of the superomedial angle (SMA) plus bursectomy can provide relief in most cases; however, the amount needed to achieve adequate scapulothoracic space decompression (SSD) is unknown. PURPOSE: The aim of this study was to evaluate the effectiveness of partial scapulectomy and the influence of bony anatomy on SSD. It was hypothesized that the anterior offset and costomedial angle would correlate with the amount of bony resection needed to achieve adequate SSD. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty pairs (n = 40) of shoulder specimens (mean age, 58 years [range, 41-64 years]; 10 male and 10 female specimens) were included. The scapula shape, medial scapula corpus angle (MSCA), anterior offset, and costomedial angle were obtained from computed tomography scans. Specimens were dissected, and each bare bony scapula was rigidly mounted. Points were collected using a 3-dimensional measuring arm. An SMA point and theoretical resection points (incremental 1-cm points up to 3 cm) proceeding laterally and medially were collected. The scapular plane was interpolated using points from the posterior scapular body. The horizontal distances of the anterior offset and each resection point to the scapular plane were calculated. The difference between the native anterior offset and the offset after resection represented the SSD. Adequate SSD was set at 5 mm. One-way analyses of variance and Pearson correlations were used with statistical significance set at P < .05. RESULTS: The maximum SSD with 3-cm resection was significantly correlated with the anterior offset ( R = 0.83, P < .001) as well as the costomedial angle ( R = -0.43, P = .006) but not the MSCA ( R = -0.11, P = .495) or scapula shape ( F2,37 = 0.39, P = .681). For the 5 scapulae with an anterior offset of less than 20 mm, a 5-mm SSD was not achieved. For 18 of 30 (60%) scapulae with an anterior offset between 20 mm and 35 mm, 3-cm resection provided at least a 5-mm SSD. For the 5 scapulae with an anterior offset of greater than 35 mm, 2-cm resection resulted in at least a 5-mm SSD in all cases. CONCLUSION: The anterior offset of the scapula appeared to be the most important bony parameter to consider during preoperative planning and the evaluation of SSD with partial scapulectomy. CLINICAL RELEVANCE: The results of this study may help surgeons with preoperative planning of surgical decompression of the scapulothoracic space for patients with symptomatic SSS.

Intraarticular arthrofibrosis of the knee alters patellofemoral contact biomechanics.

BACKGROUND: Arthrofibrosis in the suprapatellar pouch and anterior interval can develop after knee injury or surgery, resulting in anterior knee pain. These adhesions have not been biomechanically characterized. METHODS: The biomechanical effects of adhesions in the suprapatellar pouch and anterior interval during simulated quadriceps muscle contraction from 0 to 90° of knee flexion were assessed. Adhesions of the suprapatellar pouch and anterior interval were hypothesized to alter the patellofemoral contact biomechanics and increase the patellofemoral contact force compared to no adhesions. RESULTS: Across all flexion angles, suprapatellar adhesions increased the patellofemoral contact force compared to no adhesions by a mean of 80 N. Similarly, anterior interval adhesions increased the contact force by a mean of 36 N. Combined suprapatellar and anterior interval adhesions increased the mean patellofemoral contact force by 120 N. Suprapatellar adhesions resulted in a proximally translated patella from 0 to 60°, and anterior interval adhesions resulted in a distally translated patella at all flexion angles other than 15° (p < 0.05). CONCLUSIONS: The most important finding in this study was that patellofemoral contact forces were significantly increased by simulated adhesions in the suprapatellar pouch and anterior interval. Anterior knee pain and osteoarthritis may result from an increase in patellofemoral contact force due to patellar and quadriceps tendon adhesions. For these patients, arthroscopic lysis of adhesions may be beneficial.

Anatomic and Biomechanical Comparison of the Classic and Congruent-Arc Techniques of the Latarjet Procedure.

BACKGROUND: The Latarjet procedure is commonly performed using either the classic or the congruent-arc technique. Each technique has potential clinical advantages and disadvantages. However, data on the anatomic and biomechanical effects, benefits, and limitations of each technique are limited. Hypothesis/Purpose: To compare the anatomy and biomechanical fixation strength (failure load) between the 2 techniques. It was hypothesized that the classic technique would have superior initial fixation when compared with the congruent-arc technique and that this would be affected by sex and coracoid size. STUDY DESIGN: Controlled laboratory study. METHODS: A biomechanical cadaver study was performed with 20 pairs of male and female shoulders. One of each pair of shoulders was randomly assigned to receive the classic or congruent-arc technique. Coracoid and glenoid anatomic measurements were collected before biomechanical testing. A tensile force was applied through the conjoined tendon to replicate forces experienced by the coracoid graft in the early postoperative period, and the failure load was determined for each specimen. RESULTS: The mean ± SD surface area available for fixation was 263 ± 63 mm2 in the classic technique compared with 177 ± 63 mm2 in the congruent-arc group ( P < .001). 36% of the glenoid width was recreated in the classic group and 50% in the congruent-arc group ( P < .001). The congruent-arc technique resulted in a significantly lower ( P = .005) mean failure load (239 ± 91 N) compared with the classic technique (303 ± 114 N). Failure load was significantly higher in males ( P = .037); male specimens had a mean failure load of 344 ± 122 N for the classic technique and 289 ± 73 N for the congruent-arc technique, and females had a mean failure load of 266 ± 98 N and 194 ± 84 N, respectively. CONCLUSION: In this biomechanical model, the classic technique of the Latarjet procedure provided a greater surface area for healing to the glenoid and superior initial fixation when compared with the congruent-arc technique. The congruent-arc technique allowed restoration of a larger glenoid defect. CLINICAL RELEVANCE: The classic and congruent-arc techniques of coracoid transfer have anatomic and biomechanical advantages and disadvantages that should be considered when choosing between the 2 techniques.

Growth-Factor Nanocapsules That Enable Tunable Controlled Release for Bone Regeneration.

Growth factors are of great potential in regenerative medicine. However, their clinical applications are largely limited by the short in vivo half-lives and the narrow therapeutic window. Thus, a robust controlled release system remains an unmet medical need for growth-factor-based therapies. In this research, a nanoscale controlled release system (degradable protein nanocapsule) is established via in situ polymerization on growth factor. The release rate can be finely tuned by engineering the surface polymer composition. Improved therapeutic outcomes can be achieved with growth factor nanocapsules, as illustrated in spinal cord fusion mediated by bone morphogenetic protein-2 nanocapsules.

Comparison of a novel oxysterol molecule and rhBMP2 fusion rates in a rabbit posterolateral lumbar spine model.

BACKGROUND CONTEXT: The nonunion rate after lumbar spinal fusion is as high as 25%. Recombinant human bone morphogenetic protein 2 (rhBMP2) has been used as a biological adjunct to promote bony fusion. However, recently there have been concerns about BMP2. Oxysterol 133 (Oxy133) has been shown to promote excellent fusion rates in rodent lumbar spine models and offers a potential alternative to rhBMP2. PURPOSE: The purpose of this study was to compare the fusion rate of rhBMP2 and Oxy133 in a randomized controlled trial using a posterolateral lumbar rabbit spinal fusion model. STUDY DESIGN: This was a randomized control animal study. METHODS: Twenty-four male adult white New Zealand rabbits (3-3.5 kg) underwent bilateral posterolateral lumbar spinal fusion at L4-L5. Rabbits were divided into four groups: control (A), 30-µg rhBMP2 (B), 20-mg Oxy133 (C), and 60-mg Oxy133 (D). At 4 weeks, fusion was evaluated by fluoroscopy, and at 8 weeks, the rabbits were sacrificed and fusion was evaluated radiographically, by manual palpation, and with microcomputed tomography. RESULTS: Fusion rates by radiographic analysis at 8 weeks were Group A, 40.0%; Group B, 91.7%; Group C, 91.7%; and Group D, 100%. Evaluation of fusion masses by manual palpation of excised spines after sacrifice showed the following fusion rates: Group A, 0%; Group B, 83.3%; Group C, 83.3%; and Group D, 90%. Microcomputed tomography scanning confirmed these findings. CONCLUSIONS: These findings in a rabbit model demonstrate that both 20- and 60-mg Oxy133 doses promote fusion that is equivalent to fusion induced by 30-µg rhBMP2 and significantly greater than the control group. The present findings confirm that Oxy133 is a promising candidate for therapeutic development as an alternative to rhBMP2 to promote spinal fusion.

Secreted phosphoprotein 24 kD inhibits nerve root inflammation induced by bone morphogenetic protein-2.

BACKGROUND CONTEXT: Bone morphogenetic protein-2 (BMP-2) has been used to successfully promote spine fusion, but side-effects including nerve inflammation have been observed. PURPOSE: To investigate the direct neurotoxic effects of BMP-2 and test the hypotheses that the use of BMP binding proteins, such as secreted phosphoprotein 24 kD (Spp24), can reduce or eliminate these effects. STUDY DESIGN: In vitro experiments and in vivo analysis in a rodent model. METHODS: In vitro, dorsal root ganglion cells were cultured in the presence of BMP-2 with and without Spp24 and calcitonin gene-related peptide and Substance P, markers of neuroinflammation, were measured by immunohistochemistry. In vivo, rats underwent a left-sided laminotomy at L5 to expose the S1 nerve root and were randomized into four different groups according to the intervention at the laminotomy site: collagen sponge only (no BMP-2 or Spp24), BMP-2 in a collagen sponge only, BMP-2 in a collagen sponge+an empty collagen sponge to act as a barrier, and BMP-2 in a collagen sponge+Spp24 in a collagen sponge to act as a barrier. Functional evaluation was done using the Basso, Beattie, and Bresnahan scale and immunohistochemical analyses were performed using calcitonin gene-related peptide and Substance P staining. RESULTS: The neuroinflammatory effects of BMP-2 in vitro were ameliorated by the addition of Spp24. Similarly, in vivo, Spp24 reduced the expression of markers on neuroinflammation in animals treated with BMP-2 and also improved the function after BMP-2 administration. CONCLUSIONS: These results confirm that BMP binding proteins have great potential as adjuvant therapies to limit BMP-2 related side-effects in spine surgery.

Lumbar clinical adjacent segment pathology: predilection for proximal levels.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To evaluate reoperations for lumbar adjacent segment pathology (ASP) during a 10-year period. SUMMARY OF BACKGROUND DATA: ASP after lumbar arthrodesis is an important clinical problem. There remains controversy, however, on the distribution of the most commonly affected levels. METHODS: Thirty-one patients undergoing revision operation for ASP in the lumbar spine were included in this study. Patients' charts were evaluated for demographic data including age at index and revision operations, time to revision operation, and index and revision levels fused. RESULTS: L4-L5 was the most commonly instrumented level in both single-level (n = 12), and multilevel (n = 13) index fusions. The mean length of time from the index operation to revision surgery was 81 months (range, 11-570 mo). Kaplan-Meier analysis predicted a disease-free survival rate of 32.3% at 5 years and of 12.9% at 10 years after the index operation. L3-L4 was the most commonly affected level by ASP with 75% (16/20) requiring reoperation. L2-L3 was the next most commonly affected level at 52% (14/27). The L5-S1 disk was relatively protected from ASP, with only 4/17 (24%) disks at risk developing ASP. A subgroup analysis of patients undergoing revision after a single-level L4-L5 arthrodesis revealed ASP at L3-L4 in 83% (10/12) of patients, compared with only 3/12 (25%) at L5-S1 (P < 0.05). Of all cases of ASP, the proximal segments were involved 90% of the time. CONCLUSION: ASP most commonly affects proximal levels in the lumbar spine. In this cohort of patients undergoing revision fusion for ASP, 90% of affected levels were rostral to the index level(s). In patients undergoing L4-L5 single-level arthrodesis, L3-L4 is at high risk, whereas L5-S1 is somewhat protected. Surgeons should pay particular attention to proximal levels when planning a lumbar arthrodesis, however, motion segments distal to fusion may not be as protected as previously thought. LEVEL OF EVIDENCE: 4.

A novel osteogenic oxysterol compound for therapeutic development to promote bone growth: activation of hedgehog signaling and osteogenesis through smoothened binding.

Osteogenic factors are often used in orthopedics to promote bone growth, improve fracture healing, and induce spine fusion. Osteogenic oxysterols are naturally occurring molecules that were shown to induce osteogenic differentiation in vitro and promote spine fusion in vivo. The purpose of this study was to identify an osteogenic oxysterol more suitable for clinical development than those previously reported, and evaluate its ability to promote osteogenesis in vitro and spine fusion in rats in vivo. Among more than 100 oxysterol analogues synthesized, Oxy133 induced significant expression of osteogenic markers Runx2, osterix (OSX), alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN) in C3H10T1/2 mouse embryonic fibroblasts and in M2-10B4 mouse marrow stromal cells. Oxy133-induced activation of an 8X-Gli luciferase reporter, its direct binding to Smoothened, and the inhibition of Oxy133-induced osteogenic effects by the Hedgehog (Hh) pathway inhibitor, cyclopamine, demonstrated the role of Hh pathway in mediating osteogenic responses to Oxy133. Oxy133 did not stimulate osteogenesis via BMP or Wnt signaling. Oxy133 induced the expression of OSX, BSP, and OCN, and stimulated robust mineralization in primary human mesenchymal stem cells. In vivo, bilateral spine fusion occurred through endochondral ossification and was observed in animals treated with Oxy133 at the fusion site on X-ray after 4 weeks and confirmed with manual assessment, micro-CT (µCT), and histology after 8 weeks, with equal efficiency to recombinant human bone morphogenetic protein-2 (rhBMP-2). Unlike rhBMP-2, Oxy133 did not induce adipogenesis in the fusion mass and resulted in denser bone evidenced by greater bone volume/tissue volume (BV/TV) ratio and smaller trabecular separation. Findings here suggest that Oxy133 has significant potential as an osteogenic molecule with greater ease of synthesis and improved time to fusion compared to previously studied oxysterols. Small molecule osteogenic oxysterols may serve as the next generation of bone anabolic agents for therapeutic development.

Factors affecting dynamic foraminal stenosis in the lumbar spine.

BACKGROUND CONTEXT: Lumbar foraminal stenosis is a common clinical problem and a significant cause of lower extremity radiculopathy. Minimal in vivo data exists quantifying changes in foraminal area (FA) as the spine moves from flexion to extension in the lumbar spine or on the relationship between FA and lumbar segmental angular motion, translational motion (TM), or disc bulge migration. PURPOSE: To use kinetic magnetic resonance imaging (kMRI) to evaluate changes in dimensions of lumbar neural foramina during weight bearing in neutral, flexion, and extension positions. To evaluate the relationship between foraminal stenosis and lumbar segmental angular motion, TM, and disc bulge migration. STUDY DESIGN: A retrospective radiographic study. PATIENT SAMPLE: Forty-five patients with a mean age of 44 years undergoing kMRI for symptoms of low back pain or radiculopathy. OUTCOME MEASURES: Magnetic resonance imaging measurements of FA, angular motion, TM, and disc bulge migration. METHODS: Kinetic magnetic resonance imaging of the lumbar spine was reviewed in 45 patients with low back pain or radiculopathy, and parasagittal images were evaluated for changes in neural foraminal dimensions in various degrees of motion with weight bearing. The changes in foraminal dimension were correlated to the amount of segmental angular motion, TM, and disc bulge migration at each level. Neural foramina were also assessed qualitatively by Wildermuth criteria. Only those foramina that were clearly visualized with well-defined anatomic boundaries in all three positions were taken into consideration. Patients with previous surgery, tumor, and scoliosis were excluded from the study. RESULTS: There was a significant decrease in the FA from flexion to neutral (p<.05) at all levels except L5-S1 and from neutral to extension at all levels (p<.05). The average percent decrease in FA was 30.0% with the greatest decrease from flexion to extension occurring at L2-L3 (167-107 mm(2)) and the smallest change occurring at L5-S1 (135-106 mm(2)) (p<.05). The magnitude of change in FA increased as angular motion at a segment increased. The mean change in FA was 32.3 mm(2) when angular motion was less than 5° and was 75.16 mm(2) when angular motion exceeded 15°. The extent of disc bulging posteriorly in the neural foramen was also correlated with the reduction in the FA from flexion to extension, but TM had no effect. CONCLUSIONS: Foraminal area decreased significantly in extension compared with flexion and neutral on MRI. Lumbar disc bulge migration and angular motion at each level contributed independently to the decrease in FA in extension, whereas TM had no effect on FA.

Surgical management of PCL injuries: indications, techniques, and outcomes.

The ideal treatment for posterior cruciate ligament (PCL) injuries is controversial and remains an active area of orthopedic research. The indications for surgery and the ideal method of reconstruction continue to be evaluated in biomechanical and clinical studies. Recent research has provided information on the anatomy and biomechanics of the PCL, and the merits and drawbacks of the transtibial compared with the tibial inlay technique, the use of single vs double-bundle reconstruction, and different graft options for reconstruction. This review discusses important factors in the surgical treatment of PCL injuries, with attention to the most current literature on these topics.

Cross-sectional analysis of trends in meniscectomy and meniscus repair.

Knee arthroscopy to address meniscus tears is among the most common orthopedic procedures performed, and technical advances in the treatment of meniscus tears have affected the treatment options available to orthopedic surgeons. The purpose of this study was to perform a large cross-sectional analysis of orthopedic patients to investigate trends in arthroscopic meniscectomy and meniscus repair in the United States. Patients who underwent arthroscopic meniscectomy (Current Procedural Terminology codes 29881 and 29880) and arthroscopic meniscus repair (Current Procedural Terminology codes 29882 and 29883) were identified using the PearlDiver Patient Record Database, which is a national database of insurance records. The authors identified 187,607 arthroscopic medial or lateral meniscectomies and repairs performed between 2004 and 2009. Ninety-six percent of patients underwent meniscectomy and 4% underwent repair. No change occurred in the incidence of medial or lateral meniscectomy. The incidence of medial meniscus repair decreased from 5.3 cases per 10,000 patients in 2004 to 3.8 in 2009 (P<.001), although no significant change occurred in the incidence of lateral meniscus repair. Medial meniscectomy was most commonly performed in patients aged 50 to 59 years, whereas lateral meniscectomy demonstrated a bimodal age distribution. Conversely, meniscus repairs were most frequently performed in patients aged 10 to 19 years. Sex differences were more pronounced with meniscus repair (63% male vs 37% female) compared with meniscectomy (53% male vs 47% female). A high frequency of meniscus debridement can be expected in arthroscopic knee surgery. Despite advances in meniscus repair techniques and devices, no increase occurred in the performance of meniscus repair compared with meniscectomy.