Anna V. Cuomo

Mesenchymal stem cell concentration and bone repair: potential pitfalls from bench to bedside.

BACKGROUND Mesenchymal stem cells are multipotent and have the ability to differentiate into bone. We conducted a preclinical trial comparing the osteogenic potential of human bone marrow aspirate with that of mesenchymal stem cell-enriched bone marrow aspirate (both mixed with demineralized bone matrix) in a critical-sized rat femoral defect model. METHODS The buffy coat was extracted from human bone marrow aspirate to obtain mesenchymal stem cell-enriched bone marrow aspirate. Fifty-nine athymic rats, each with a 6-mm femoral defect, were divided into six treatment groups: defect only (Group I), demineralized bone matrix and saline solution (Group II), demineralized bone matrix and bone marrow aspirate (Group III), demineralized bone matrix and mesenchymal stem cell-enriched bone marrow aspirate (Group IV), demineralized bone matrix and recombinant human bone morphogenetic protein-2 (rhBMP-2) (Group V [positive control]), and absorbable collagen sponge and rhBMP-2 (Group VI [positive control]). All animals were killed at twelve weeks for radiographic, micro-computed tomography, histomorphometric, and histologic analysis. RESULTS There was wide variability in the mesenchymal stem cell concentrations obtained from the human donors. All ten defects healed in the positive control groups (Groups V and VI). Only one defect healed in each experimental group (Groups II, III, and IV) (i.e., three of forty-four defects healed). There was no significant difference among the radiographic scores of Groups II, III, and IV (p = 0.59), and the score for each of those groups was significantly higher than that for Group I (p <or= 0.005) and significantly lower than those for Groups V and VI (p <or= 0.001). The bone volume and mineral density did not differ among Groups III, IV, and V (p = 0.53). The percent total bone volume and percent normal bone volume in Group VI were significantly higher than those values in Groups I, III, and IV (p < 0.0001) and those in Group II (p = 0.048). In Groups II through V, the cortical bone was more dense than the lace-like bone in Group VI. CONCLUSIONS Neither bone marrow aspirate nor mesenchymal stem cell-enriched bone marrow aspirate mixed with demineralized bone matrix resulted in reliable healing of critical-sized bone defects. It is possible that a greater number of mesenchymal stem cells or an enhanced osteoinductive signal is required for adequate bone-healing. Mesenchymal stem cell and/or carrier variability may also contribute to differences in bone formation.

Influence of short-term adenoviral vector and prolonged lentiviral vector mediated bone morphogenetic protein-2 expression on the quality of bone repair in a rat femoral defect model

The objective of this study was to compare the efficacy of adenoviral and lentiviral regional gene therapy in a rat critical sized femoral defect model. The healing rates and quality of bone repair of femoral defects treated with syngeneic rat bone marrow cells (RBMCs) transduced with either lentiviral vector (Group I) or adenoviral vector (Group II) expressing bone morphogenetic protein-2 (BMP-2) gene were assessed. RBMCs transduced with the adenoviral vectors produced more than 3 times greater (p<0.001) BMP-2 when compared to RBMCs transduced with lentiviral vectors in an in vitro evaluation. Serial bioluminescent imaging demonstrated short duration luciferase expression (less than 3 weeks) in defects treated with RBMCs co-transduced with two adenoviral vectors (Group IV; adenovirus expressing BMP-2 and luciferase [Ad-BMP-2+Ad-Luc]). In contrast, the luciferase signal was present for 8 weeks in defects treated with RBMCs co-transduced with two lentiviral vectors (Group III; lentivirus expressing BMP-2 and luciferase gene [LV-BMP-2+LV-Luc]). There were no significant differences with respect to the radiological healing rates (p=0.12) in defects treated with lentiviral versus adenoviral mediated BMP-2 gene transfer. Biomechanical testing of healed Group I femoral specimens demonstrated significantly higher energy to failure (p<0.05) when compared to Group II defects. Micro CT analysis revealed higher bone volume/tissue volume fraction (p=0.04) in Group I defects when compared to Group II defects. In conclusion, prolonged BMP-2 expression associated with lentiviral mediated gene transfer demonstrated a trend towards superior quality of bone repair when compared to adenoviral mediated transfer of BMP-2. These results suggest that the bone repair associated with regional gene therapy is influenced not just by the amount of protein expression but also by duration of protein production. This observation needs validation in a more biologically challenging environment where differences in healing rates and quality of bone repair are more likely to be significantly different.

Health-Related Quality of Life Outcomes Improve After Multilevel Surgery in Ambulatory Children With Cerebral Palsy

Background: Studies evaluating multilevel surgery to treat spastic deformity and functional deficits in cerebral palsy (CP) usually focus on data from instrumented gait analysis and clinical examination without examining functional and health-related quality of life (HRQOL) outcomes. Recently, outcome measures for well-being in children with a variety of musculoskeletal disorders have also been validated specifically for CP. Therefore, this study aimed to investigate the impact of multilevel surgery on the function and HRQOL in a group of ambulatory children with CP. Methods: In a multicenter prospective trial, 57 ambulatory children with CP, mean age 9.5 years, underwent multilevel soft tissue surgery to correct sagittal imbalance. Validated clinical outcome measures for HRQOL were administered preoperatively and postoperatively with an average follow-up time of 15.2 months. The functional and psychosocial components of the Pediatric Outcomes Data Collection Instrument (PODCI), Pediatric Quality of Life Questionnaire (PedsQL), and the Functional Assessment Questionnaire Walking Score were used. Results: Significant improvements in outcome scores occurred postoperatively in the following: PedsQL parent-total (17.6%; P < 0.001) and parent-physical sections (25.0%; P < 0.001), the Functional Assessment Questionnaire Walking Score (15.3%; P < 0.001), and the PODCI sections for transfers and basic mobility (15.8%; P < 0.001), sports and physical function (23.9%; P = 0.012), and global (12.9%; P < 0.001). Improvements also occurred in the PedsQL child-total (8.4%; P = 0.104) and child-physical sections (8.6%; P = 0.189), but these were not statistically significant. There were no significant changes in the PODCI parent-derived pain (−3.2%; P = 0.504) and happiness sections (1.9%; P = 0.645). Conclusions: Multilevel surgery in ambulatory patients with CP improves function and HRQOL. However, improved functional well-being does not imply improved psychosocial well-being, and patients and their families should be counseled accordingly. Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.

Evidence into practice: Emergency physician management of common pediatric fractures

Objectives Randomized trials have shown that removable immobilization devices are at least as good as circumferential casts for the management of common specific types of pediatric wrist and ankle fractures. Our main objective was to determine the proportion of emergency physicians who prescribe removable devices for distal radius buckle fractures and/or nondisplaced distal fibular Salter-Harris I fractures. We also examined follow-up referral patterns for these injuries. Methods This was an online survey of members of 2 national emergency physician associations in Canada: Pediatric Emergency Research Canada and the Canadian Association of Emergency Physicians. Results Of the 849 eligible participants, 447 responded to the survey, yielding an aggregate response rate of 52.7%. Organization-specific response rates were 169 (70.4%) of 240 for the Pediatric Emergency Research Canada and 278 (45.6%) of 609 for the Canadian Association of Emergency Physicians. Overall, 263 of 416 (63.2%; 95% confidence interval [CI], 58.6–67.8) of emergency physicians treat buckle fractures of the distal radius with a removable splint and refer 212 of 398 (53.3%; 95% CI, 48.4–58.2) of these injuries to the primary care physician for follow-up. For Salter-Harris I fractures of the distal fibula, emergency physicians treat 201 of 416 (48.3%; 95% CI, 43.5–53.1) with a removable ankle support and refer 94 of 398 (23.6%; 95% CI, 19.4–27.8) to the primary care physician for follow-up. Conclusions At least 50% of the surveyed Canadian emergency physicians treat distal radius buckle fractures and/or Salter-Harris I fibular fractures with a removable immobilization device, and the primary care physician follow-up of these injuries occur with some regularity for both these injuries.

Static and dynamic gait parameters before and after multilevel soft tissue surgery in ambulating children with cerebral palsy

Background Recent studies have questioned the efficacy of releasing hip flexion contractures and the resulting ankle position after tendoachilles lengthening in ambulating children with cerebral palsy (CP). Methods Twenty-three ambulatory children with CP underwent 96 soft tissue-lengthening procedures without bony surgery. Preoperative and postoperative clinical and computerized gait data were reviewed. Results Static contractures improved reliably, with improvements in all areas measured, including hip flexion contracture (14 degree improvement), hip abduction (19 degree improvement), popliteal angle (26 degree improvement), and ankle dorsiflexion (11 degree improvement). The changes in computerized gait data were less uniform. The knees showed significant benefits, as evidenced by improved maximal knee extension in stance phase (37.3 degree preop and 19.9 degree postop) and at initial contact (51.6 degree preop and 34.8 degree postop). At the hip, a statistically significant improvement was only seen in maximum hip extension in stance phase (minimum hip flexion), and the magnitude of this change was only 4.6 degree (15.3 to 10.7 degree). There were no significant changes at the pelvis. At the ankle, the tendency was toward calcaneal gait after Achilles tendon lengthening, with excessive dorsiflexion seen both in stance (17.3 degree) and at toe off (−6.9 degree). Temperospatial parameters showed improved stride length, but no significant changes in gait velocity or cadence. Discussion The persistence of crouch postoperatively, though improved, likely limited the potential changes in hip kinematics. As this study excluded patients undergoing osseous surgery, it is possible that lever arm dysfunction may have contributed to the ongoing crouch. The results of this study suggest that static contractures and knee kinematics improve reliably after soft tissue surgery in children with CP, but that caution must be exercised when considering heel cord lengthening in these children. Level of Evidence Therapeutic level II. See Instructions to Authors for a complete description of levels of evidence.

Evidence into practice: Pediatric orthopaedic surgeon use of removable splints for common pediatric fractures

Objectives: Removable splints when compared with circumferential casts in randomized trials have been shown to be a safe and cost-effective method of managing many common minor distal radius and fibular fractures. This study estimated the extent to which this evidence is being implemented in clinical practice, and determined the perceived barriers to the adoption of this evidence. Methods: A cross-sectional survey of practicing orthopaedic surgeon members of the Pediatric Orthopedic Surgeons of North America (POSNA) was conducted, using a 22-item online questionnaire, and distributed using a modified Dillman technique. Survey questions were derived from and validated by literature review, expert opinion, and pilot-testing on the targeted sample before implementation. Results: Of the 826 eligible participants, 558 (67.6%) responded to the survey. Of these, 505 (90.5%) had completed a fellowship in pediatric orthopaedics, 335 (60.0%) worked in a university-affiliated setting, and 377 (67.6%) had been in practice for <20 years. Only 158/543 [29.1%; 95% confidence interval (CI), 25.28, 32.92] reported using a removable splint to treat buckle fractures of the distal radius; 32 (5.9%; 95% CI, 3.9, 7.9) and 8 (1.5%; 95% CI, 0.5, 2.5) would use such splints for minimally displaced greenstick and transverse fractures of the distal radius, respectively. For distal fibular avulsion fractures, 122 (22.5%; 95% CI, 19.0, 26.0) would use a removable splint; 57 (10.5%; 95% CI, 7.9, 13.1) and 28 (5.6%; 95% CI, 3.7, 7.5) would do so for nondisplaced Salter-Harris I and II fractures of the distal fibula, respectively. The most commonly reported perceived barriers to application of a removable device were concerns about patient compliance, potential complications, and possible medicolegal implications. Conclusions: Only a relatively small proportion of practicing POSNA use such splints for minor distal radius and distal fibular fractures. These data support the need for implementation of knowledge translation strategies (eg, education) targeted at all the stakeholders to encourage pediatric orthopaedic surgeons to change practice in keeping with the best evidence for these common and stable injuries. Level of Evidence: Level II.

Gartland type I supracondylar humerus fractures in children: is splint immobilization enough?

Objective The primary objective of this study was to determine if Gartland type I supracondylar humerus (SCH) fractures undergo significant displacement resulting in a change in management when treated with a long-arm splint. Secondary objectives included measured changes at follow-up in displacement and/or angulation. Methods This was a retrospective review of children who presented with elbow injuries to a children’s hospital. Patients were included if they were diagnosed with a Gartland type I SCH fracture, managed with a long-arm splint, and had at least 1 follow-up visit 2 to 3 weeks from the emergency department visit. The primary outcome was the proportion of cases that required the placement of a circumferential cast and/or an operative intervention. Secondary outcomes included the proportion of cases with significant changes in displacement on any view, Baumann or the lateral humerocapitellar angle, and/or category of position of anterior humeral line relative to capitellum. Results Of 804 elbow injuries that presented from 2003 to 2008, 53 patients met the inclusion criteria. The median age of the patients was 4.1 years (interquartile range, 3.4–6.1 years) years. Of the 53, there were no cases that required a change in management. One case had a change in the humerocapitellar angle, and another had a change of 1 category in position of the capitellum relative to the anterior humeral line. There were no other cases of significant changes in displacement or angulation. Conclusions These data support that Gartland type I SCH fractures can be treated effectively with long-arm posterior splinting for the duration of therapy.

The Future of Musculoskeletal Tissue Regeneration: A Clinical Perspective

Over the past decade significant advances have occurred with our understanding of the molecular pathways related to the repair for hard and soft tissues of the musculoskeletal system. It is essential that this information be translated from the bench to the bedside to create novel treatment regimens that advance the care of patients. The purpose of this chapter is to elucidate therapeutic regimens that may be developed in the future. Over the next two to 10 years there will be an intense focus on developing targeted delivery of bioactive substances that employ minimally invasive surgical techniques. Treatments in the remote future will require knowledge related to the host biologic potential, disease risk stratification and prevention strategies for the musculoskeletal patient. A case study is presented to explore the potential clinical future.

Management of Terminal Osseous Overgrowth of the Humerus With Simple Resection and Osteocartilaginous Grafts.

Background: Osseous overgrowth is a common complication in children after humeral transcortical amputation. Capping tibial overgrowth with the proximal fibula has been shown to be the most effective treatment. However, best treatment practices are not clear for the humerus. We compared patients treated surgically for humeral osseous overgrowth with simple resection or autologous osteocartilaginous graft to determine if this treatment were as effective in the humerus as it has been in the tibia. Methods: A retrospective review of humeral amputees from 1987 to 2011 at a pediatric hospital was performed. Patients with 2 years follow-up who underwent surgical treatment for established humeral overgrowth were included. Patients initially managed with simple resection were compared with those managed with autologous osteocartilaginous grafts. Descriptive statistics were calculated for demographic and outcome variables. T tests and &khgr;2 tests were used to compare differences between groups. Results: Eighteen humeri in 16 patients met inclusion criteria. Mean age at surgery was 8.3 (2.6 to 13.6) years and mean follow-up was 6.3 (1.5 to 10.4) years. Thirteen humeri underwent simple resection, with recurrent overgrowth in 9, and revision surgery in 8 at a mean 2.6 years. Five humeri were primarily managed with autologous osteocartilaginous grafts. Two developed non–overgrowth-related complications at 1 and 42 months. Including revision procedures after simple resection, 10 humeri were managed with autologous osteocartilaginous grafts. Thirty percent (3/10) required revision surgery; however, there were no cases of recurrent overgrowth. &khgr;2 comparison showed lower rates of complications (P=0.004) and reoperation (P=0.012) with capping as compared with simple resection. Conclusions: Autologous osteocartilaginous capping of the humerus has a significantly lower rate of complications and reoperation compared with simple resection. However, the capping procedure has the potential for other complications related to difficulty with graft fixation. Surgeons should be aware that the outcomes are not as consistent as when the technique is applied to osseous overgrowth of the tibia and anticipate the possibilities of hardware prominence and difficulty with fixation. Level of Evidence: Level 3—therapeutic-retrospective comparative.

A practical approach to determining the center of the femoral head in subluxated and dislocated hips

Background: Mistaking the ossific nucleus as the surrogate for the center of the femoral head affects treatment decisions in hip dysplasia. Previous studies of ossific nucleus position within the femoral head have been qualitative, or, have not included both subluxated and dislocated hips. The purpose of this study was, first, to determine the most accurate radiographic landmark to define the center of the immature femoral head in hip dysplasia, and, second, to quantitatively analyze the position of the ossific nucleus relative to the center of the femoral head. Methods: The center of the femoral head was determined from hip arthrograms for 19 consecutive patients with untreated hip dysplasia. Three radiographic proxies for the center were defined on each film: (1) the center of the proximal physis; (2) the center of the ossific nucleus; and (3) a modification of Mose’s concentric circles. Each point was compared with the true center of the head on an arthrogram. Results: Nineteen patients of an average age of 35.5 months (range, 9 to 76 mo) yielded 22 dysplastic hips. Modified Mose circle was the most accurate technique. In subluxated hips, the center of the femoral physis was equally accurate. The ossific nucleus was the poorest estimation of the center of the femoral head. All of the ossific nuclei were located cephalad and lateral to the center of the femoral head as determined on arthrogram. Conclusions: The modified Mose technique is the most accurate technique for determining the center of the femoral head. In subluxated hips, the center of the physis is a practical, equivalent, technique. The ossific nucleus is a poor proxy for the center of the head in hip dysplasia. Clinical Relevance: A modification of Mose’s technique is the most accurate assessment of the center of the femoral head in both subluxated and dislocated hips. The center of the physis is a practical, reliable, surrogate for the center of the head in subluxated hips without requiring an arthrogram.