Isolated pelvic ring injuries: functional outcomes following percutaneous, posterior fixation.

OBJECTIVES: To characterize pelvic-specific functional outcomes in patients with isolated, partially unstable (AO/OTA 61-B), pelvic ring injuries treated with posterior only percutaneous screw fixation of the pelvic ring. PATIENTS AND METHODS: Between September 2007 and October 2011, 16 subjects (mean age 42.4 years; range 18-90 years) with isolated, partially unstable pelvic ring injuries (AO/OTA 61-B) were treated with percutaneous, posterior pelvic ring fixation. Subjects underwent an evaluation of pelvic ring function with a modification of Majeed's pelvic functional outcome assessment tool. Subjects were excluded if they sustained a concomitant long-bone fracture, visceral injury requiring surgery, spinal cord injury, and an injury to the anterior pelvic ring or acetabulum requiring additional fixation. RESULT: Mean follow-up was 30.8 (range 14-55) months. Eleven subjects sustained unilateral posterior ring injuries, and five subjects sustained bilateral posterior ring injuries. All fractures healed uneventfully, and no hardware failures were noted. Average pelvic functional outcome score at final follow-up was 85.3 % (good). All but subjects required assistive walking devices and gait and sitting comfort scored "excellent." High rates of sexual dysfunction and persistent difficulty with daily activities were noted in this series. CONCLUSIONS: This series demonstrates that activity-specific dysfunction persists years after definitive percutaneous posterior fixation of isolated pelvic ring injuries. Radiographic outcomes were excellent as were subjects' ability to ambulate independently and sit comfortably without pain. Many complained of persistent discomfort with both daily activities and sexual activity, suggesting persistent pathology to the non-osseous structures about the pelvis.

Arthroscopic repair of large rotator cuff tears using the double-row technique: an analysis of surgeon experience on efficiency and outcomes.

BACKGROUND: Arthroscopic rotator cuff repair is one of the most commonly performed procedures in the orthopaedic specialty. The goal of this study was to evaluate the effect(s) of surgical experience on efficiency and patient outcomes after double-row rotator cuff repair. METHODS: A retrospective review of 69 consecutive patients with large rotator cuff tears who underwent double-row arthroscopic rotator cuff repair by 1 surgeon from the start of practice was conducted. We divided the patients into 2 cohorts: group 1, early (first 18 months of study period) (n = 35), and group 2, recent (final 12 months of study period) (n = 34). Outcome measures including American Shoulder and Elbow Surgeons score, Penn Shoulder Score, and range of motion were assessed preoperatively and at final follow-up. In addition, we compared the operative times between the groups. RESULTS: At a mean follow-up of 13.25 months, both cohorts showed significant improvement (P < .001) in American Shoulder and Elbow Surgeons scores (from 47.9 to 76.5 and from 43.6 to 79.4 in groups 1 and 2, respectively) and Penn Shoulder Scores (from 45.8 to 80 and from 38.7 to 79.6 in groups 1 and 2, respectively) postoperatively. The magnitude of change and final scores were similar between the groups. Similar improvements in range of motion were noted in both groups. Patients in group 1 had a statistically significantly longer mean operative time than those in group 2 (116 minutes vs 99.7 minutes, P = .036). CONCLUSION: Double-row rotator cuff repair provides predictable improvement in pain and function. It can be performed effectively early in a surgeon's career. However, with experience, efficiency is improved.

Foot and ankle infections: diagnosis and management.

Infections of the foot are a common source of morbidity, disability, and potential limb loss. A large proportion of lower extremity infections occurs in the setting of diabetic neuropathy, with or without circulatory compromise, and are potentially preventable with regular surveillance. Adequate diagnosis and treatment of foot infections can be challenging. Successful treatment is dependent on factors such as etiology; vascular, neurologic, and immune status; and the identity of the offending organism.

Thoracic Curve Correction Ratio: An Objective Measure to Guide against Overcorrection of a Main Thoracic Curve in the Setting of a Structural Proximal Thoracic Curve.

Purpose: The correction of double thoracic (Lenke 2) curves has been associated with higher rates of postoperative shoulder imbalance that may compromise long-term outcomes following spinal deformity correction. A number of methods have been proposed to mitigate this risk, though no accepted standard measurement exists. The purpose of this study is to validate a novel quantitative method of determining the relative curve correction magnitude in double thoracic curves. Methods: Retrospective data from a multi-center database of patients undergoing surgical correction of left-proximal thoracic, right-main thoracic Lenke 2 curves were analyzed. A novel measurement tool, the Thoracic Curve Correction Ratio (TCCR), was applied for the purposes of validation against historical data. Results: A total of 305 patients with complete two-year follow-up data were included. The TCCR, or the ratio of postoperative percent correction of the thoracic curves divided by the ratio of the preoperative curve magnitudes, displayed a significant negative correlation (Pearson R = −0.66; p < 0.001) with T1 tilt at two years postoperatively. Conclusions: The TCCR could be added as an important factor in the preoperative planning process and intraoperative assessment in order to reduce postoperative T1 tilt. While T1 tilt remains an imperfect surrogate measure for clinical shoulder balance, it serves as one of many potential measures that the surgeon may evaluate quantitatively and radiographically.

Limb salvage after infected knee arthroplasty with bone loss and extensor mechanism deficiency using a modular segmental replacement system.

Multiple total knee arthroplasty revisions pose significant surgical challenges, such as bone loss and soft tissue compromise. For patients with bone loss and extensor mechanism insufficiency after total knee arthroplasty, arthrodesis is a treatment option for the avoidance of amputation. However, arthrodesis is both difficult to achieve in situations with massive bone loss and potentially undesirable due to the dramatic shortening that follows. Although intramedullary nailing for knee arthrodesis has been widely reported, this technique has traditionally relied on the achievement of bony union. We report a case of a patient with massive segmental bone loss in which a modular intercalary prosthesis was used for arthrodesis to preserve limb length without bony union.

Change in rates of primary atlantoaxial spinal fusion surgeries in the United States (1993-2015).

OBJECTIVE: The objective of this study was to investigate revision burden and associated demographic and economic data for atlantoaxial (AA) fusion procedures in the US. METHODS: Patient data from the National Inpatient Sample (NIS) database for primary AA fusion were obtained from 1993 to 2015, and for revision AA fusion from 2006 to 2014 using ICD-9 procedure codes. Data from 2006 to 2014 were used in comparisons between primary and revision surgeries. National procedure rates, hospital costs/charges, length of stay (LOS), routine discharge, and mortality rates were investigated. RESULTS: Between 1993 and 2014, 52,011 patients underwent primary AA fusion. Over this period, there was a 111% increase in annual number of primary surgeries performed. An estimated 1372 patients underwent revision AA fusion between 2006 and 2014, and over this time period there was a 6% decrease in the number of revisions performed annually. The 65-84 year-old age group increased as a proportion of primary AA fusions in the US from 35.9% of all AA fusions in 1997 to 44.2% in 2015, an increase of 23%. The mean hospital cost for primary AA surgery increased 32% between 2006 and 2015, while the mean cost for revision AA surgery increased by 35% between 2006 and 2014. Between 2006 and 2014, the mean hospital charge for primary AA surgery increased by 67%; the mean charge for revision surgery over that same period increased by 57%. Between 2006 and 2014, the mean age for primary AA fusions was 60 years, while the mean age for revision AA fusions was 52 years. The mean LOS for both procedures decreased over the study period, with primary AA fusion decreasing by 31% and revision AA fusion decreasing by 24%. Revision burden decreased by 21% between 2006 and 2014 (mean 4.9%, range 3.2%-6.4%). The inpatient mortality rate for primary AA surgery decreased from 5.3% in 1993 to 2.2% in 2014. CONCLUSIONS: The number of primary AA fusions between 2006 and 2014 increased 22%, while the number of revision procedures has decreased 6% over the same period. The revision burden decreased by 21%. The inpatient mortality rate decreased 62% (1993-2014) to 2.2%. The increased primary fusion rate, decreased revision burden, and decreased inpatient mortality determined in this study may suggest an improvement in the safety and success of primary AA fusion.

The impact of prophylactic intraoperative vancomycin powder on microbial profile, antibiotic regimen, length of stay, and reoperation rate in elective spine surgery.

BACKGROUND CONTEXT: There is growing concern that the microbial profile of surgical site infection (SSI) in the setting of prophylactic vancomycin powder may favor more resistant and uncommon organisms. PURPOSE: To demonstrate the impact of prophylactic intraoperative vancomycin powder on microbial profile, antibiotic regimen, length of stay (LOS), and reoperation rate in spine surgical site infection. STUDY DESIGN AND/OR SETTING: Retrospective cohort study. PATIENT SAMPLE: the study included 115 postoperative spine patients who were required to return to the operating room for SSI. OUTCOME MEASURES: The outcome measures were microbial profile, reoperation rate, antibiotic regimen, and LOS for patients with postoperative spine infection who either did (treated) or did not (untreated) receive prophylactic vancomycin powder during their index procedure. METHODS: A retrospective review of patients who underwent posterior thoracic and/or lumbar spine surgery between 2010 and 2017 was conducted. Those undergoing surgical treatment of SSI were identified, and patients were divided into two groups - those who were treated with intraoperative vancomycin (treated) and those who were not (untreated). The organism profile for each group was compared. The average LOS, reoperation rate, and number of patients requiring more than 1 antibiotic were calculated for each patient in both groups. RESULTS: There were 5,909 procedures performed. One hundred and fifteen SSIs were identified, resulting in a 1.9% infection rate. Prophylactic vancomycin powder was used in the index procedure for 42 of those cases. 23.8% of cultures in the vancomycin group were polymicrobial and 16.7% were gram-negative compared with 9.6% (p=0.039) and 4.1% (p=0.021) in the untreated group, respectively. In the vancomycin-treated group, 26.1% of patients underwent repeat irrigation and debridement compared with 38.4% in the untreated group (p=0.184). The percentage of patients in the treatment and untreated group who required more than 1 antibiotic was 26.0% and 26.1%, respectively (p=0.984). Mean LOS in the treatment group was 8.0 versus 7.9 for the untreated group (p=0.945) CONCLUSIONS: In this series, vancomycin powder was associated with a higher prevalence of gram-negative and polymicrobial organisms in patients that ultimately developed postoperative SSI. However, this did not adversely affect the need for multiple reoperations, antibiotic regimen, or LOS for these patients.

Total Disk Replacement Adjacent to a Multilevel Fusion in the Cervical Spine: A Biomechanical Motion Analysis.

OBJECTIVE: Cervical total disk replacement (TDR) has emerged as a motion-preserving alternative to anterior cervical diskectomy fusion (ACDF). Biomechanical studies have demonstrated that the TDR preserves motion at the diseased segment and minimizes motion and stress at adjacent segments compared with fusion. There has been growing interest in performing a TDR adjacent to a cervical fusion. The purpose of this study was to investigate the kinematics of a TDR after sequentially fusing adjacent segments. METHODS: Seven fresh-frozen human cadaveric cervical spine specimens from C1-T1 were used (average age, 56.2 ± 7.3 years). The effect on cervical flexion-extension motion, by instrumenting a TDR above or below a 1-, 2-, or 3-level fusion, was measured. The protocol consisted of taking fluoroscopic images of each cervical specimen obtained at maximal angular displacement in flexion and extension during force application. Cobb angles were measured on digital radiographs to determine flexion-extension range of motion (ROM). RESULTS: Segmental ROM of the C6-7 TDR in the unfused spine was 11.3° ± 1.9°. After performing a 3-level fusion at C3-6, the motion of the C6-7 TDR increased to 12.9° ± 1.3° (P = 0.33). ROM of the C2-3 TDR in the unfused spine was 5.0° ± 1.1°. After performing a 3-level fusion of C3-6, the C2-3 TDR segmental motion was 6.1° ± 1.3° (P = 0.09). CONCLUSIONS: Biomechanically performing a cervical TDR adjacent to a long-segment fusion did not subject the implant to significantly greater motion than when the TDR was instrumented alone.

Prevalence of cervical spinal injury in trauma.

OBJECT: Diagnosis of cervical spinal injury (CSI) is an essential aspect of the trauma evaluation. This task is especially difficult in patients who are not clinically able to be evaluated (unevaluable) because of distracting painful injuries, intoxication, or concomitant head injury. For this population, the appropriate use of advanced imaging techniques for cervical spinal clearance remains undetermined. This study was undertaken to estimate the prevalence of unstable CSI, particularly among patients in whom clinical evaluation is impossible or unreliable. METHODS: Estimates of the prevalence of CSI in populations consisting of all trauma patients, alert patients only, and clinically unevaluable patients only were determined by variance-weighted pooling of data from 65 publications (281,864 patients) that met criteria for review. RESULTS: The overall prevalence of CSI among all trauma patients was 3.7%. The prevalence of CSI in alert patients was 2.8%, whereas unevaluable patients were at increased risk of CSI with a prevalence of 7.7% (p = 0.007). Overall, 41.9% of all CSI cases were considered to exhibit instability. CONCLUSIONS: Trauma patients who are clinically unevaluable have a higher prevalence of CSI than alert patients. Knowledge of the prevalence and risk of such injuries may help establish an evidence-based approach to the detection and management of clinically occult CSI.

In vivo performance of an acellular disc-like angle ply structure (DAPS) for total disc replacement in a small animal model.

Total intervertebral disc replacement with a biologic engineered disc may be an alternative to spinal fusion for treating end-stage disc disease. In previous work, we developed disc-like angle ply structures (DAPS) that replicate the structure and function of the native disc and a rat tail model to evaluate DAPS in vivo. Here, we evaluated a strategy in which, after in vivo implantation, endogenous cells could colonize the acellular DAPS and form an extracellular matrix organized by the DAPS topographical template. To do so, acellular DAPS were implanted into the caudal spines of rats and evaluated over 12 weeks by mechanical testing, histology, and microcomputed tomography. An external fixation device was used to stabilize the implant site and various control groups were included to evaluate the effect of immobilization. There was robust tissue formation within the DAPS after implantation and compressive mechanical properties of the implant matched that of the native motion segment. Immobilization provided a stable site for fibrous tissue formation after either a discectomy or a DAPS implantation, but bony fusion eventually resulted, with segments showing intervertebral bridging after long-term implantation, a process that was accelerated by the implanted DAPS. Thus, while compressive mechanical properties were replicated after DAPS implantation, methods to actively prevent fusion must be developed. Future work will focus on limiting fusion by remobilizing the motion segment after a period of integration, delivering pro-chondrogenic factors, and pre-seeding DAPS with cells prior to implantation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:23-31, 2017.

Referral Patterns of Emergent Pediatric Hand Injury Transfers to a Tertiary Care Center.

Several studies have identified the inappropriate use of emergent interfacility transfer as an opportunity to improve health care use. The authors sought to identify common characteristics among children who were transferred from a community hospital to a pediatric tertiary care center for definitive treatment of hand/wrist injuries. All patients undergoing emergent transfer to a pediatric Level I trauma center and academic tertiary referral center for evaluation and management of injuries to the hand/wrist during the 2-year study period were retrospectively identified. Demographic and transfer data were abstracted from the medical record. Referring hospitals were subcategorized by the presence or absence of hand surgical emergency department coverage and the capability to admit/operate on children. Overall, 169 patients were identified who transferred to the authors' institution for hand injuries. There were no differences in the day or time of transfer. Of those transferred, 59 (35%) were admitted for definitive care, of whom 51 (86%) required a surgical intervention within 24 hours. Of the remaining 110 (65%) patients discharged from the emergency department, 27 (25%) underwent elective surgical intervention within 2 weeks. There were a greater number of transfers from institutions without the ability to admit children, regardless of hand surgical emergency department coverage status. Understanding pediatric referral patterns may improve use of emergency department facilities because most patients who were transferred were discharged the same day. Educational outreach and improved interfacility communication may result in enhanced resource use for evaluation and management of pediatric hand injuries.

Outcomes of Lisfranc Injuries in the National Football League.

BACKGROUND: Tarsometatarsal (Lisfranc) joint injuries commonly occur in National Football League (NFL) competition; however, the career effect of these injuries is unknown. PURPOSE: To define the time to return to competition for NFL players who sustained Lisfranc injuries and to quantify the effect on athletic performance. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Data on NFL players who sustained a Lisfranc injury between 2000 and 2010 were collected for analysis. Outcomes data included time to return to competition, total games played after season of injury, yearly total yards and touchdowns for offensive players, and yearly total tackles, sacks, and interceptions for defensive players. Offensive power ratings (OPR = [total yards/10] + [total touchdowns × 6]) and defensive power ratings (DPR = total tackles + [total sacks × 2] + [total interceptions × 2]) were calculated for the injury season and for 3 seasons before and after the injury season. Offensive and defensive control groups consisted of all players without an identified Lisfranc injury who competed in the 2005 season. RESULTS: The study group was composed of 28 NFL athletes who sustained Lisfranc injuries during the study period, including 11 offensive and 17 defensive players. While 2 of 28 (7.1%) players never returned to the NFL, 26 (92.9%) athletes returned to competition at a median of 11.1 (interquartile range [IQR], 10.3-12.5) months from time of injury and missed a median of 8.5 (IQR, 6.3-13.0) regular-season games. Analysis of pre- and postinjury athletic performance revealed no statistically significant changes after return to sport after Lisfranc injury. The magnitude of change in median OPR and DPR observed in offensive and defensive Lisfranc-injured study groups, -34.8 (IQR, -64.4 to 1.4) and -13.5 (-30.9 to 4.3), respectively, was greater than that observed in offensive and defensive control groups, -18.8 (-52.9 to 31.5) and -5.0 (-22.0 to 14.0), respectively; however, these differences did not reach statistical significance (P = .33 and .21, respectively). Evaluation of the durability of injured players after the season of injury revealed no statistically significant difference in career length compared with controls. CONCLUSION: More than 90% of NFL athletes who sustained Lisfranc injuries returned to play in the NFL at a median of 11.1 months from time of injury. Offensive and defensive players experienced a decrease in performance after return from injury that did not reach statistical significance compared with their respective control groups over a similar time period.

Delayed Postoperative Neurologic Deficits in Spinal Deformity Surgery.

STUDY DESIGN: A cross-sectional survey of surgeon members of the Scoliosis Research Society (SRS). OBJECTIVE: This study sought to characterize the incidence, clinical presentation, diagnostic workup, treatment, and neurologic prognosis following delayed postoperative neurologic deficit (DPND) in patients undergoing spinal deformity surgery. SUMMARY OF BACKGROUND DATA: DPND is a potentially devastating condition following spinal surgery, characterized by the development of a neurological deficit within hours or days of the surgical procedure. To date, only case reports and small case series have been published on the topic. METHODS: We developed a survey to characterize DPND following spinal deformity surgery. This survey was distributed to surgeon members of the SRS through email and standard mail. The overall response rate was 38% (352/929). RESULTS: Our results suggest an estimated DPND incidence of 1 of 9910 cases (0.01%). Eighty-one surgeons (23%) experienced at least 1 DPND in the past 10 years (92 total cases). Most common diagnoses were scoliosis (69%), kyphosis (23%), and spondylolisthesis (14%); 20% were revision surgeries. The number of hours to deficit onset was as follows: 1 to 12 (36%), 13 to 24 (27%), 25 to 48 (27%), more than 48 (10%). The most commonly cited sources of injury included ischemic injury (38%) and cord compression (15%). Forty-one percent experienced complete neurologic recovery, 26% partial, and 33% no recovery. Twenty-one percent of patients achieved final neurologic status within 1 week, 38% by 1 month, and 73% by 6 months. Patients with compression-related DPND had a significantly greater likelihood of experiencing some neurologic recovery (≥1 ASIA Grade) than ischemia-related DPND (86% versus 51%, P = 0.049). CONCLUSIONS: DPND occurs at an estimated incidence of 0.01%. Sixty-three percent of DPND cases occurred within the first 24 hours and 90% within 48 hours. Complete (41%) or partial (26%) neurologic recovery may be expected, especially in compression-related DPND, emphasizing the need for perioperative vigilance, prompt recognition, and early intervention. LEVEL OF EVIDENCE: 4.

Effects of Mesenchymal Stem Cell and Growth Factor Delivery on Cartilage Repair in a Mini-Pig Model.

OBJECTIVE: We have recently shown that mesenchymal stem cells (MSCs) embedded in a hyaluronic acid (HA) hydrogel and exposed to chondrogenic factors (transforming growth factor-ß3 [TGF-ß3]) produce a cartilage-like tissue in vitro. The current objective was to determine if these same factors could be combined immediately prior to implantation to induce a superior healing response in vivo relative to the hydrogel alone. DESIGN: Trochlear chondral defects were created in Yucatan mini-pigs (6 months old). Treatment groups included an HA hydrogel alone and hydrogels containing allogeneic MSCs, TGF-ß3, or both. Six weeks after surgery, micro-computed tomography was used to quantitatively assess defect fill and subchondral bone remodeling. The quality of cartilage repair was assessed using the ICRS-II histological scoring system and immunohistochemistry for type II collagen. RESULTS: Treatment with TGF-ß3 led to a marked increase in positive staining for collagen type II within defects (P < 0.05), while delivery of MSCs did not (P > 0.05). Neither condition had an impact on other histological semiquantitative scores (P > 0.05), and inclusion of MSCs led to significantly less defect fill (P < 0.05). For all measurements, no synergistic interaction was found between TGF-ß3 and MSC treatment when they were delivered together (P > 0.05). CONCLUSIONS: At this early healing time point, treatment with TGF-ß3 promoted the formation of collagen type II within the defect, while allogeneic MSCs had little benefit. Combination of TGF-ß3 and MSCs at the time of surgery did not produce a synergistic effect. An in vitro precultured construct made of these components may be required to enhance in vivo repair in this model system.

A radiopaque electrospun scaffold for engineering fibrous musculoskeletal tissues: Scaffold characterization and in vivo applications.

Tissue engineering strategies have emerged in response to the growing prevalence of chronic musculoskeletal conditions, with many of these regenerative methods currently being evaluated in translational animal models. Engineered replacements for fibrous tissues such as the meniscus, annulus fibrosus, tendons, and ligaments are subjected to challenging physiologic loads, and are difficult to track in vivo using standard techniques. The diagnosis and treatment of musculoskeletal conditions depends heavily on radiographic assessment, and a number of currently available implants utilize radiopaque markers to facilitate in vivo imaging. In this study, we developed a nanofibrous scaffold in which individual fibers included radiopaque nanoparticles. Inclusion of radiopaque particles increased the tensile modulus of the scaffold and imparted radiation attenuation within the range of cortical bone. When scaffolds were seeded with bovine mesenchymal stem cells in vitro, there was no change in cell proliferation and no evidence of promiscuous conversion to an osteogenic phenotype. Scaffolds were implanted ex vivo in a model of a meniscal tear in a bovine joint and in vivo in a model of total disc replacement in the rat coccygeal spine (tail), and were visualized via fluoroscopy and microcomputed tomography. In the disc replacement model, histological analysis at 4 weeks showed that the scaffold was biocompatible and supported the deposition of fibrous tissue in vivo. Nanofibrous scaffolds that include radiopaque nanoparticles provide a biocompatible template with sufficient radiopacity for in vivo visualization in both small and large animal models. This radiopacity may facilitate image-guided implantation and non-invasive long-term evaluation of scaffold location and performance. STATEMENT OF SIGNIFICANCE: The healing capacity of fibrous musculoskeletal tissues is limited, and injury or degeneration of these tissues compromises the standard of living of millions in the US. Tissue engineering repair strategies for the intervertebral disc, meniscus, tendon and ligament have progressed from in vitro to in vivo evaluation using a variety of animal models, and the clinical application of these technologies is imminent. The composition of most scaffold materials however does not allow for visualization by methods available to clinicians (e.g., radiography), and thus it is not possible to assess their performance in situ. In this work, we describe a radiopaque nanofibrous scaffold that can be visualized radiographically in both small and large animal models and serve as a framework for the development of an engineered fibrous tissue.

Development of a Large Animal Model of Osteochondritis Dissecans of the Knee: A Pilot Study.

BACKGROUND: Treatment of osteochondritis dissecans (OCD) of the knee is challenging, and evidence for stage-dependent treatment options is lacking. Basic science approaches utilizing animal models have provided insight into the etiology of OCD but have yet to produce a reliable and reproducible large animal model of the disease on which to test new surgical strategies. PURPOSE/HYPOTHESES: The purpose of this study was to develop an animal model featuring an OCD-like lesion in terms of size, location, and International Cartilage Repair Society (ICRS) grading. The hypothesis was that surgical creation of an osteochondral defect followed by placement of a barrier between parent bone and progeny fragment would generate a reproducible OCD-like lesion. STUDY DESIGN: Controlled laboratory study. METHODS: Bilateral osteochondral lesions were created in the medial femoral condyles of 9 Yucatan minipigs. After lesion creation, a biodegradable membrane was interposed between the progeny and parent bone. Five different treatment groups were evaluated at 2 weeks: a control with no membrane (ctrl group; n = 4), a slowly degrading nanofibrous poly(∊-caprolactone) membrane (PCL group; n = 4), a fenestrated PCL membrane with 1.5-mm holes covering 25% of surface area (fenPCL group; n = 4), a collagen membrane (Bio-Gide) (CM group; n = 3), and a fenestrated CM (fenCM group; n = 3). Five unperturbed lateral condyles (1 from each treatment group) served as sham controls. After euthanasia on day 14, the lesion was evaluated by gross inspection, fluoroscopy, micro-computed tomography (micro-CT), and histology. To quantify changes between groups, a scoring system based on gross appearance (0-2), fluoroscopy (0-2), and micro-CT (0-6) was established. Micro-CT was used to quantify bone volume per total volume (BV/TV) in a defined region surrounding and inclusive of the defect. RESULTS: The no scaffold group showed healing of the subchondral bone at 2 weeks, with continuity of subchondral bone elements. Conversely, condyles treated with PCL or CM showed substantial remodeling, with loss of bone in both the progeny fragment and surrounding parent bone. When these membranes were fenestrated (fenPCL and fenCM groups), bone loss was less severe. Histological analysis showed no integration in the cartilage layer in any treatment group, while fibrous tissue formed between the parent and progeny fragments. Micro-CT showed significant differences in mean BV/TV between the PCL (27.4% ± 2.3%) and the sham (47.7% ± 1.4%) or no scaffold (54.9% ± 15.1%) groups (P < .01 and P < .05, respectively). In addition, a significant difference in bone loss was evident between the PCL and fenPCL groups (mean BV/TV, 46.6% ± 15.2%; P < .05), as well as between the PCL and fenCM (mean BV/TV, 50.9% ± 3.5%) and fenPCL groups (P < .01). Grading by 6 blinded reviewers using an OCD scoring system with 3 subcategories showed a significant difference between control and PCL groups. CONCLUSION: This study successfully developed a large animal model of OCD-like lesions in the knee joint of Yucatan minipigs. The lesions generated matched characteristics of an ICRS grade 3 OCD lesion in humans. These findings set the stage for ongoing model refinement as well as exploration of novel interventional therapies to restore function and bone and cartilage patency in individuals affected by this rare but significant disease. CLINICAL RELEVANCE: This developed model will serve as a platform on which to further investigate the natural course as well as emerging treatment options for OCD.

Cartilage repair and subchondral bone remodeling in response to focal lesions in a mini-pig model: implications for tissue engineering.

OBJECTIVE: Preclinical large animal models are essential for evaluating new tissue engineering (TE) technologies and refining surgical approaches for cartilage repair. Some preclinical animal studies, including the commonly used minipig model, have noted marked remodeling of the subchondral bone. However, the mechanisms underlying this response have not been well characterized. Thus, our objective was to compare in-vivo outcomes of chondral defects with varied injury depths and treatments. DESIGN: Trochlear chondral defects were created in 11 Yucatan minipigs (6 months old). Groups included an untreated partial-thickness defect (PTD), an untreated full-thickness defect (FTD), and FTDs treated with microfracture, autologous cartilage transfer (FTD-ACT), or an acellular hyaluronic acid hydrogel. Six weeks after surgery, micro-computed tomography (µCT) was used to quantitatively assess defect fill and subchondral bone remodeling. The quality of cartilage repair was assessed using the ICRS-II histological scoring system and immunohistochemistry for type II collagen. A finite element model (FEM) was developed to assess load transmission. RESULTS: Using µCT, substantial bone remodeling was observed for all FTDs, but not for the PTD group. The best overall histological scores and greatest type II collagen staining was found for the FTD-ACT and PTD groups. The FEM confirmed that only the FTD-ACT group could initially restore appropriate transfer of compressive loads to the underlying bone. CONCLUSIONS: The bony remodeling observed in this model system appears to be a biological phenomena and not a result of altered mechanical loading, with the depth of the focal chondral defect (partial vs. full thickness) dictating the bony remodeling response. The type of cartilage injury should be carefully controlled in studies utilizing this model to evaluate TE approaches for cartilage repair.

Translation of an engineered nanofibrous disc-like angle-ply structure for intervertebral disc replacement in a small animal model.

Intervertebral disc degeneration has been implicated in the etiology of low back pain; however, the current surgical strategies for treating symptomatic disc disease are limited. A variety of materials have been developed to replace disc components, including the nucleus pulposus (NP), the annulus fibrosus (AF) and their combination into disc-like engineered constructs. We have previously shown that layers of electrospun poly(ε-caprolactone) scaffold, mimicking the hierarchical organization of the native AF, can achieve functional parity with native tissue. Likewise, we have combined these structures with cell-seeded hydrogels (as an NP replacement) to form disc-like angle-ply structures (DAPS). The objective of this study was to develop a model for the evaluation of DAPS in vivo. Through a series of studies, we developed a surgical approach to replace the rat caudal disc with an acellular DAPS and then stabilized the motion segment via external fixation. We then optimized cell infiltration into DAPS by including sacrificial poly(ethylene oxide) layers interspersed throughout the angle-ply structure. Our findings illustrate that DAPS are stable in the caudal spine, are infiltrated by cells from the peri-implant space and that infiltration is expedited by providing additional routes for cell migration. These findings establish a new in vivo platform in which to evaluate and optimize the design of functional disc replacements.

Major complications and comparison between 3-column osteotomy techniques in 105 consecutive spinal deformity procedures.

STUDY DESIGN: A retrospective review. OBJECTIVE: To characterize the risk factors for the development of major complications in 3-column osteotomies and determine whether the presence of a major complication affects ultimate clinical outcomes. SUMMARY OF BACKGROUND DATA: Three-column spinal osteotomies, including pedicle subtraction osteotomy (PSO) and vertebral column resection (VCR), are common techniques to correct severe and/or rigid spinal deformities. METHODS: Two hundred forty consecutive PSO (n = 156) and VCR (n = 84) procedures in 237 patients were performed at a single institution between 1995 and 2008. Of these, 105 patients (87 PSOs, 18 VCRs) had complete preoperative and minimum 2-year postoperative clinical outcomes data available for analysis. Using established criteria, we reported complications as major or minor and further stratified complications as surgical versus medical and permanent versus transient. Risk factors for complications and their effect on Scoliosis Research Society (SRS) clinical outcomes at baseline and at 2 years or more were assessed. RESULTS: Major medical and surgical complications occurred at similar rates in both PSOs and VCRs (38%, 33 of 87 vs. 22%, 4 of 18; P = 0.28). Overall, 24.8% (26 of 105) experienced major surgical complications (3 permanent) and 15.2% (16 of 105) experienced major medical complications (4 permanent). Patients with PSO were older (53 vs. 29 yr; P < 0.001), had greater estimated blood loss (1867 vs. 1278 mL; P = 0.02), and showed a trend toward fewer fused levels (10.1 vs. 12.2; P = 0.06). Risk factors for major complications included preoperative sagittal imbalance of 40 mm or more (P = 0.01), age 60 years and older (P = 0.01), and the presence of 3 or more medical comorbidities (P = 0.04). Both groups improved significantly from baseline in SRS subscores; however, patients with PSO started off worse but improved more than VCRs in both the pain (+1.0 vs. +0.1; P < 0.001) and function (+0.6 vs. +0.2; P = 0.01) domains, with no differences in final satisfaction (4.1 vs. 4.3; P = 0.54). PSO and VCR patients with no complications had slightly higher satisfaction scores than patients with minor-only complications, major transient complications, and major permanent complications. There were no significant differences among the groups with respect to change in SRS subscores from baseline, and all complication groups improved significantly from baseline (P = 0.04). CONCLUSION: Major complications occurred in 35% of 3-column osteotomies and at similar rates for both PSO (38%) and VCR (22%) procedures. The presence of a major complication did not affect the ultimate clinical outcomes at 2 years or more.