Patient Self-Reported Allergies and Their Correlation with Thoracic Outlet Syndrome Outcomes

OBJECTIVES

Thoracic outlet syndrome (TOS) is an uncommon neurovascular disorder that presents as neck and upper extremity pain secondary to brachial plexus trunk or subclavian vasculature compression. The orthopedic literature has correlated patient-reported allergies to postoperative patient-reported outcome (PRO) scores for a variety of surgical procedures. We sought to evaluate patient-reported allergies and PROs following surgical decompression for TOS.

METHODS

A chart review was conducted after identifying patients who underwent surgical thoracic outlet decompression by a single surgeon. Patients were contacted and administered five PRO questionnaires via telephone: the QuickDASH Outcome Measure questionnaire (disabilities of the arm, shoulder, and hand [DASH]), the Cervical Brachial Symptom Questionnaire, the Single Assessment Numeric Evaluation, the 12-Item Short Form Survey, and the Numeric Rating Scale (a visual analogue scale). A bivariate analysis of Pearson's correlation coefficient (r) was used to determine the associations of allergies with questionnaires and demographic variables.

RESULTS

Of the 393 patients (128 males and 265 females) identified in the study, 75 (24%) responded and completed all of the questionnaires, 18 (24%) males and 57 (76%) females. A significant correlation was found between the number of allergies reported and the QuickDASH Outcome Measure questionnaire (r = 0.375, P < 0.001), the Cervical Brachial Symptom Questionnaire (r = 0.295, P = 0.01), change in the Single Assessment Numeric Evaluation score (r = -0.310, P < 0.01), change in the visual analogue scale (r = 0.244, P = 0.035), sex (r = 0.245, P = 0.034), and the number of medications (r = 0.642, P < 0.001).

CONCLUSIONS

The increased frequency of patient-reported allergies is significantly associated with worse PRO scores for women undergoing TOS surgical decompression. Better understanding this association can help physicians counsel patients on expected outcomes.

Impact of irradiation on load-to-failure in bone-patellar tendon-bone allografts: A systematic review and meta-analysis

Introduction

To evaluate the impact various levels of irradiation have on bone-patellar tendon-bone (BTB) allograft load-to-failure.

Materials and methods

Pubmed, Google Scholar and Embase were searched for studies reporting load-to-failure measurements of BTB allografts following gamma or eBeam irradiation. All systematic reviews, editorials, as well as studies that utilized animal models and/or other graft sources (achilles, hamstring, quadriceps) were excluded. Meta-analysis was performed to compare the impact of low dose (19 ≤ kGy), intermediate (20-49 kGy) and high dose (>50 kGy) gamma and eBeam radiation on load-to-failure.

Results

Twelve studies, containing a total of 429 BTB allografts (159 controls, 270 irradiated), were identified. Load-to-failure of BTB allograft was significantly decreased at intermediate (20-49 kGy) doses of radiation, while low (≤19 kGy) and high (>50 kGy) doses did not significantly change load-to-failure.

Conclusions

Intermediate doses of radiation may negatively impact the biomechanical integrity of BTB allograft in vitro. Future studies are required to examine clinical outcomes at varying irradiation levels.

Is the Synovium the First Responder to Posttraumatic Knee Joint Stress? The Molecular Pathogenesis of Traumatic Cartilage Degeneration

OBJECTIVE

The aim of this study was to evaluate if a similar catabolic and inflammatory gene pattern exists between the synovium, hyaline cartilage, and blood of patients with the knee joint tissues and if one precedes the other.

DESIGN

A total of fifty-eight patients (34 females and 24 males) with a mean age of 44.7 years (range, 18-75) underwent elective knee arthroscopy due to previously diagnosed pathology. Full blood samples were collected preoperatively from synovium and cartilage samples intraoperatively. Real time PCR with spectrophotometric analysis was performed. Following genes taking part in ECM (extracellular matrix) remodeling were selected for analysis: MMP-1, MMP-2, MMP-8, MMP-9, MMP-13, MMP-14, ADAMTS-4 (Agg1) and ADAMTS-5 (Agg2) proteases, TIMP-1, and TIMP-2 - their inhibitors - and IL-1 and TNF-α cytokines.

RESULTS

Analysis revealed a strong and significant correlation between gene expression in synovial and systemic blood cells (p <0.05 for all studied genes) with ADAMTS-4, ADAMTS-5, IL-1, TNF-α and TIMP-2 expression most positively correlated with an R>0.8 for each. An analysis between chondrocytes and systemic blood gene expression shown no significant correlation for all genes. Bivariate correlation of International Cartilage Repair Society grading and genes expression revealed significant associations with synovial MMP-1, MMP-2, MMP-8, MMP-9, IL-1, TNF-α and TIMP-2.

CONCLUSION

We suggest that the synovial tissue is the first responder for knee joint stress factors in correlation with the response of blood cells. The chondrocyte's genetic response must be further investigated to elucidate the genetic program of synovial joints, as an organ, during OA development and progression.

Orthopedic consequences of modern gladiators: a systematic review of lower extremity musculoskeletal issues in retired NFL players

OBJECTIVES

The stressors that National Football League (NFL) athletes face are well-described and documented with regard to multisystem afflictions and injury prevalence. However, the majority of literature discusses the short-term effects rather than long-term outcomes of playing professional football. The purpose of this study was to characterize the long-term musculoskeletal issues in the retired NFL population.

METHODS

Publications from CENTRAL, Scopus, Medline, PubMed, Embase, and Google Scholar were searched from database inception to February 2021. A total of 9 cohort studies evaluating lower extremity arthritis in retired NFL athletes were included for review. Two reviewers extracted data from the individual studies, including demographic information (age, body mass index, length of career, position), injury descriptions (location of injury, number of injuries, diagnoses), and procedure (total knee and or hip arthroplasty) frequency.

RESULTS

Arthritis in retired NFL players was more than twice as prevalent than the general United States male population (95% CI: 2.1-2.3). Ankle osteoarthritis was directly correlated with the number of foot and ankle injuries. Players <50 years of age had a 16.1 and 13.8 times higher risk of undergoing TKA and THA, respectively, when compared to the general population. In older age groups, this trend held with retired NFL players being at least 4.3 and 4.6 times more likely than members of the general population to undergo TKA and THA, respectively.

CONCLUSION

This review demonstrates that the effects of NFL-related lower extremity injuries extend beyond the players' careers and present a higher risk for early-onset osteoarthritis and overall frequency of undergoing total knee and hip arthroplasty.

Gender Disparities Among Professional Team Sports Medicine Physicians

OBJECTIVE

Although recent trends from the Accreditation Council for Graduate Medical Education (ACGME) present encouraging growth of female representation in sports medicine, the field is still lagging behind other specialties. This study investigates gender disparities among physicians providing care for professional sports teams in male and female sports leagues.

DESIGN

Information regarding physicians providing sports medicine care to professional teams obtained by database queries (May 2021). Chi-square analysis compared gender data of orthopaedic team physicians with American Orthopaedic Society for Sports Medicine (AOSSM) and American Academy of Orthopaedic Surgeons (AAOS) membership, residency, and fellowship census data. Primary care sports medicine physicians were compared with American Medical Society for Sports Medicine (AMSSM) and primary-care sports medicine fellowship census data.

SETTING

Professional sports health care.

STUDY POPULATION

Professional league physicians.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Gender, residency, and fellowship training of professional league physicians.

RESULTS

Among a total of 608 team physicians, 572 (93.5%) were male and 40 (6.5%) were female. Orthopedic surgeons comprised 64.7% of the physicians. Fourteen (3.6%) team orthopedic surgeons were female. Thirty-five percent of team physicians were primary care sports medicine physicians. Twenty-six primary care sports medicine physicians (11.6%) were female. Orthopaedic female team physician representation overall was comparable with AOSSM and AAOS membership but significantly less than orthopaedic surgery residents and sports medicine fellows ( P < 0.01). Women's National Basketball Association orthopaedic team physicians were more represented than female membership among AOSSM, AAOS, and orthopaedic sports medicine fellows ( P < 0.01). Except for the WNBA, Premiere Hockey Federation, National Women's Soccer League, and United States Football League, female primary care sports medicine physicians were underrepresented in professional sports compared with AMSSM membership and primary care sports fellows ( P < 0.01).

CONCLUSION

Overall, female representation is poor among orthopaedic surgeons and primary care physicians providing sports medicine care to professional teams. Leagues encompassing female athletes tend to have better representation of female physicians.

LEVEL OF EVIDENCE

IV.

The incidence of shoulder arthroplasty infection presents a substantial economic burden in the United States: a predictive model

Background

Periprosthetic joint infections (PJIs) are a major cause of morbidity after shoulder arthroplasty. Prior national database studies have estimated the trends of shoulder PJI up to 2012.²¹ Since 2012, the landscape of shoulder arthroplasty has changed drastically with the expanding popularity of reverse total shoulder arthroplasty. The dramatic growth in primary shoulder arthroplasties is likely paralleled with an increase of PJI case volume. The purpose of this study is to quantify the rise in shoulder PJIs and the economic stress they currently place on the American healthcare system as well as the toll they will incur over the coming decade.

Methods

The Nationwide Inpatient Sample database was queried for primary and revision anatomic total shoulder arthroplasty, reverse total shoulder arthroplasty, and hemiarthroplasty from 2011-2018. Multivariate regression was used to predict cases and charges through the year 2030 adjusted to 2021 purchasing power parity.

Results

From 2011 to 2018, PJI was found to be 1.1% shoulder arthroplasties, from 0.8% (2011) to 1.4% (2018). Anatomic total shoulder arthroplasty experienced the greatest proportion of infections at 2.0%, followed by hemiarthroplasty at 1.0% and reverse total shoulder arthroplasty at 0.3%. Total hospital charges grew 324%, from $44.8 million (2011) to $190.3 million (2018). Our regression model projects 176% growth in cases and 141% growth in annual charges by 2030.

Conclusion

This study demonstrates the large economic burden that shoulder PJIs pose on the American healthcare system, which is predicted to reach nearly $500 million in charges annually by 2030. Understanding trends in procedure volume and hospital charges will be critical in evaluating strategies to reduce shoulder PJIs.

Home-Based Physical Therapy Results in Similar Outcomes to Formal Outpatient Physical Therapy after Reverse Shoulder Arthroplasty: a Randomized Control Trial

INTRODUCTION

Outcomes following reverse total shoulder (RTSA) arthroplasty are influenced by surgical indications, surgical technique, implant design and patient variables. The role of self-directed postoperative physical therapy (PT) is poorly understood following RTSA. The purpose of this study was to compare the functional and patient reported outcomes (PRO) of a formal physical therapy program to a home therapy program after undergoing a reverse total shoulder arthroplasty.

METHODS

One hundred patients were prospectively randomized into two groups: formal PT (F-PT) and home-based PT (H-PT). Patient demographic variables along with range of motion (ROM), strength measurements and SST, ASES, SANE, VAS, PHQ-2 outcomes were collected preoperatively and at 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively. Patient perceptions regarding their individual group, F-PT versus H-PT, were also assessed.

RESULTS

Sixty-eight patients were included for analysis with 37 in the H-PT group and 33 in the F-PT group. Thirty patients in both groups had a minimum of 6 months follow-up. Average follow-up was 20.8 months. Forward flexion, abduction, internal rotation and external rotation ROM did not differ between groups at final follow-up. Strength did not differ between groups with the exception of external rotation, which was greater with formal physical therapy by 0.8 kg/f (p=0.04). PRO at final follow-up did not differ between therapy groups. Patients receiving home-based therapy appreciated the convenience and cost-savings and the majority felt this was less burdensome.

CONCLUSION

Formal physical therapy and home-based physical therapy programs after reverse shoulder arthroplasty result in similar improvements in range of motion, strength, and PRO scores.

LEVEL OF EVIDENCE

Level I; Randomized Controlled Trial; Treatment Study.

Extensor Mechanism Reconstruction for Chronic Patellar Tendon Tears

OBJECTIVES

Reconstruction for a chronic patellar tendon rupture in a native knee is an uncommon surgical procedure. Although there have been case series investigating patient-reported outcomes, there is no systematic review of these studies to date. The purpose of this review is to synthesize the literature on this procedure to better understand its outcomes, complications, and surgical technique options.

METHODS

A systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify studies that reported outcomes and techniques of patellar tendon reconstruction for chronic disruption in native knees. Searches were conducted through MEDLINE using PubMed, Cochrane Database of Systematic Reviews, and clinicaltrials.gov.

RESULTS

Ten studies with 103 patients and 105 knees were included. Results for nonnative (arthroplasty) knees were excluded. The mean patient age was 40.3 years, and the mean postsurgical follow-up time was 53.8 months. Of the 105 knees, 75% received a hamstring tendon graft, whereas 13% received a bone-tendon-bone graft and 7% received a whole extensor mechanism allograft. The mean preoperative range of motion was 113.8°, which improved to 126.0° postoperatively. The mean preoperative Lysholm score was 58.6, which improved to 86.0 postoperatively; 100% of patients returned to their normal work activities and 76% returned to their prior level of physical activity. There were no major complications reported in any of the included studies.

CONCLUSIONS

Chronic patellar tendon disruption in a native knee is an uncommon injury that can result in significant limitations for patients. Although more research is needed to better elucidate which graft is best, outcomes after patellar tendon reconstruction for chronic tears appear to be satisfactory with current techniques.

Nerve block with liposomal bupivacaine yields fewer complications and similar pain relief when compared to an interscalene catheter for arthroscopic shoulder surgery: a randomized controlled trial

BACKGROUND

Following orthopedic surgery, patients frequently experience pain and discomfort. Multiple methods of regional anesthesia are available; however, the optimal technique to adequately manage pain while minimizing complications remains under investigation. This study aims to compare the complication rates and pain relief of single-injection, liposomal bupivacaine brachial plexus nerve block to a conventional, indwelling ropivacaine interscalene catheter (ISC) in patients undergoing arthroscopic shoulder surgery. We hypothesize that liposomal bupivacaine will have fewer patient complications with similar pain relief than an indwelling catheter.

METHODS

Patients undergoing arthroscopic shoulder surgery were prospectively assessed after randomization into either ropivacaine ISC or single-injection liposomal bupivacaine brachial plexus nerve block (LB) arms. All patients were discharged with 5 analgesics (acetaminophen, methocarbamol, gabapentin, acetylsalicylic acid, and oxycodone) for as-needed pain relief. Preoperatively, patient demographics and baseline Visual Analog Scale, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons, and Penn Shoulder Scores were obtained. For the first four days postoperatively, complication rates (nausea, dyspnea, anesthetic site discomfort and/or irritation and/or leakage, and self-reported concerns and complications), pain, medication usage, and sleep data were assessed by phone survey every 12 hours. The primary outcome was overall complication rate. At 12 weeks postoperatively, Visual Analog Scale, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons, and Penn scores were reassessed. Outcome scores were compared with Mann-Whitney U tests, and demographics were compared with chi-squared tests. Significance was set at P < .05.

RESULTS

A total of 63 individuals were allocated into ISC (N = 35) and in the LB arms (N = 28) for analysis. Demographics and preoperative patient-reported outcomes were not different between the arms. Patients in the LB arm experienced fewer (13.1%) overall complications than those in the ISC arm (29.8%) (P < .001), with patients in the ISC arm specifically reporting more anesthetic site discomfort (36.4% vs. 7.1%, P = .007), leakage (30.3% vs. 7.1%, P = .023), and 'other,' free-response complications (ISC: 21.2%; LB: 3.6%; P = .042). No differences were noted in pain, sleep, opioid use, or satisfaction between arms during the perioperative period. More nonopioid medications were consumed on average in the ISC (1.8 ± 1.4) than in the LB arm (1.4 ± 1.3) (P = .001), with greater reported use of acetylsalicylic acid (40.9% vs. 23.4% P < .001) and acetaminophen (69.5% vs. 59.6% P = .013). Patient-reported outcome scores did not differ between groups preoperatively or at 12 weeks.

DISCUSSION

Patients receiving liposomal bupivacaine experienced fewer complications than traditional ISCs after arthroscopic shoulder surgery. Analgesia, sleep, satisfaction, and functional scores were similar between the 2 groups.

Anatomic Structures at Risk When Utilizing Percutaneous Intramedullary Fibular Screw Fixation for Lateral Malleolus Fractures: A Cadaveric Study

Category:

Ankle

Introduction/Purpose:

Isolated lateral malleolus fractures are a common ankle fracture that a foot and ankle surgeon will encounter. Retrograde intramedullary fixation for unstable lateral malleolus fractures has become a viable option for patients at higher risk for potentially devastating wound complications. The aim of this cadaveric study was to assess the relative risk of injuring adjacent anatomic structures with percutaneous implantation of an intramedullary fibular screw for lateral malleolus fractures to minimize iatrogenic injury.

Methods:

Seven fresh-frozen below-the-knee cadaver specimens were used for this study. Prior to investigations, specimens were inspected with fluoroscopic radiographs for preexisting pathology or prior surgical intervention. Lateral dissection of the lateral malleolus was performed after screw placement to determine the proximity of the peroneus longus (PL), peroneus brevis (PB), and sural nerve (SN) to the inserted hardware. The mean, standard deviation, and range for distances were calculated for all structures. Analysis of variance (ANOVA) was used to determine statistical significance.

Results:

Percutaneous intramedullary fibular screw placement was performed in seven specimens, six females and one male, with an average age of 79.3 +- 8.1 years. Amongst the seven specimens, only one resulted in an injury to a structure of interest (sural nerve). The peroneus longus and peroneus brevis were not injured in any of the specimens. Table 1 shows the average distance between the guidewire and each structure of interest.

Conclusion:

This study shows the potential risks to lateral structures when placing an intramedullary fibular screw for unstable lateral malleolus fractures. We suggest that orthopedic surgeons exercise caution when performing critical steps of the procedure to minimize avoidable injury to structures of importance that may increase the morbidity of the patient.

Patient Reported Outcomes Following Hindfoot Fusion Utilizing the Triple Arthrodesis Procedure

Category:

Hindfoot; Ankle Arthritis

Introduction/Purpose:

Fusions are used as a salvage procedure to improve stability and return patient to regular functions of daily activities. Triple Arthrodesis is a fusion of three joints, talonavicular, subtalar, calcaneocuboid. There is limited literature on the patient-reported long-term outcomes for this procedure. The aim of this study is to quantify the patient-reported outcomes for the Triple Arthrodesis procedure.

Methods:

A retrospective analysis was conducted for patients that underwent Triple Arthrodesis at our facility from 2014-2021. Using the electronic medical record (EMR), basic patient demographics, time since surgery, presence of osteoarthritis or rheumatoid arthritis, development of infection, nonunion, hardware failure, and history of previous foot and ankle procedures were all noted. Additionally, we recorded the hardware used during the operation and whether concomitant procedures were performed during the time of surgery. To evaluate outcomes, we used the Patient Reported Outcomes Measurement Information System (PROMIS) survey and Foot Function Index (FFI) scores.

Results:

A total of 132 patients were included in this study with 50 participants completing the PROMIS and FFI surveys. The average time point at which the outcomes were collected was 5.50 years postoperatively. Postoperative PROMIS scores for physical function, pain interference, and depression were all within one standard deviation of the reference population. The average PROMIS physical function was 38.35, pain interference was 61.52, and depression was 49.82 for this population. The mean FFI scores were 58.56 for pain, 60.06 for disability, 48.06 for activity limitation. There was a significant decrease in postoperative pain scores when compared to preoperative pain of 5.4 to 2.55 (p=0.023). Four patients experienced wound infection, four patients experienced nonunion, six patients required revisional surgery, and three patients experienced hardware failure.

Conclusion:

Preliminary results Triple Arthrodesis may be beneficial in decreasing pain and lead variable long-term patient satisfaction. We plan to include further statistical analysis comparing the various types of fixation techniques used and the resultant PROMIS and FFI scores. Additionally, we are currently continuing patient calls to collect more completed PROMIS and FFI reports.

Tarsometatarsal Joint Preparation using a Modified Dorsal Approach vs Standard Approach: A Cadaver Study

Category:

Midfoot/Forefoot

Introduction/Purpose:

Lisfranc injuries are a relatively common midfoot injury involving the tarsometatarsal (TMT) joint. Surgical fixation typically involves open reduction with internal fixation or primary arthrodesis of the joint(s). The standard surgical approach to the TMT joint involves two dorsal incisions however, a recent study has suggested the use of a modified single dorsal incision approach. The goal of this paper is to compare the total surface area of the joint that can be prepared for primary arthrodesis of the TMT using the standard vs modified single dorsal approach.

Methods:

Ten fresh frozen below-the-knee cadaver specimens were randomly assigned to receive either the standard or modified dorsal single incision operative approach to the TMT joint. Prior to initiating the study, specimens were inspected with fluoroscopic radiographs for preexisting pathology or prior surgical intervention. The joint surface was visualized and then underwent articular preparation as for a joint fusion. After adequate joint preparation, the TMT joint was disarticulated and the surface was photographed for image analysis. Using ImageJ, articular joint surface preparation areas were measured by two blinded reviewers. to assess the joint surface preparation and this was compared by surgical approach.

Results:

After ImageJ and Mann-Whitney U statistical analysis, there was no significant difference in the amount of joint prepared when comparing the standard versus modified dorsal approach for the first three TMT joints (p= 0.548, p=0.310, p= 0.548). The percentage of joint preparation utilizing the standard dorsal approach versus the modified dorsal approach for TMT joints one through three are as follows (percentages utilized are listed as the median value with its correlating range): First TMT- 67.6% (range 26%) by the standard approach versus 71.7% (range 9%) by the modified dorsal approach, second TMT- 67.9% (range 24%) versus 65.7% (range 12%), and third TMT- 65.9% (range 42%) versus 59.6% (range 24%). Table 1 summarizes our results between each operative approach.

Conclusion:

With our findings, we demonstrate that a modified single dorsal approach to the Lisfranc joint provided comparable joint preparation for primary arthrodesis as the standard dual incision approach. However, the modified dorsal approach may be beneficial in that it avoids creating a skin bridge which has potential for necrosis with the standard two incision approach. The authors believe the comparable joint preparation combined with its potential to alleviate soft tissue complications make the modified dorsal approach a viable surgical approach for a TMT arthrodesis.

Lentiviral Gene Therapy for Bone Repair Using Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells

Umbilical cord blood (UCB) has been increasingly explored as an alternative source of stem cells for use in regenerative medicine due to several advantages over other stem-cell sources, including the need for less stringent human leukocyte antigen matching. Combined with an osteoinductive signal, UCB-derived mesenchymal stem cells (MSCs) could revolutionize the treatment of challenging bone defects. This study aimed to develop an ex vivo regional gene-therapy strategy using BMP-2-transduced allogeneic UCB-MSCs to promote bone repair. To this end, human UCB-MSCs were transduced with a lentiviral vector carrying the cDNA for BMP-2 (LV-BMP-2). In vitro assays to determine the UCB-MSC osteogenic potential and BMP-2 production were followed by in vivo implantation of LV-BMP-2-transduced UCB-MSCs in a mouse hind-limb muscle pouch. Non-transduced and LV-GFP-transduced UCB-MSCs were used as controls. Transduction with LV-BMP-2 was associated with abundant BMP-2 production and induction of osteogenic differentiation in vitro. Implantation of BMP-2-transduced UCB-MSCs led to robust heterotopic bone formation 4 weeks postoperatively, as seen on radiographs and histology. These results, along with the fact that UCB-MSCs can be easily collected with no donor-site morbidity and low immunogenicity, suggest that UCB might be a preferable allogeneic source of MSCs to develop an ex vivo gene-therapy approach to treat difficult bone-repair scenarios.

CaMKII inhibition in human primary and pluripotent stem cell-derived chondrocytes modulates effects of TGFβ and BMP through SMAD signaling

OBJECTIVE

Upregulation of calcium/calmodulin-dependent kinase II (CaMKII) is implicated in the pathogenesis of osteoarthritis (OA) and reactivation of articular cartilage hypertrophy. However, direct inhibition of CaMKII unexpectedly augmented symptoms of OA in animal models. The role of CaMKII in OA remains unclear and requires further investigation.

METHODS

Analysis of CaMKII expression was performed in normal human and OA articular chondrocytes, and signaling mechanisms were assessed in articular, fetal and Pluripotent Stem Cell (PSC)-derived human chondrocytes using pharmacological (KN93), peptide (AC3-I) and small interfering RNA (siRNA) inhibitors of CaMKII.

RESULTS

Expression levels of phospho-CaMKII (pCaMKII) were significantly and consistently increased in human OA specimens. BMP2/4 activated expression of pCaMKII as well as COLII and COLX in human adult articular chondrocytes, and also increased the levels and nuclear localization of SMADs1/5/8, while TGFβ1 showed minimal or no activation of the chondrogenic program in adult chondrocytes. Targeted blockade of CaMKII with specific siRNAs decreased levels of pSMADs, COLII, COLX and proteoglycans in normal and OA adult articular chondrocytes in the presence of both BMP4 and TGFβ1. Both human fetal and PSC-derived chondrocytes also demonstrated a decrease of chondrogenic differentiation in the presence of small molecule and peptide inhibitors of CaMKII. Furthermore, immunoprecipitation for SMADs1/5/8 or 2/3 followed by western blotting for pCaMKII showed direct interaction between SMADs and pCaMKII in primary chondrocytes.

CONCLUSION

Current study demonstrates a direct role for CaMKII in TGF-β and BMP-mediated responses in primary and PSC-derived chondrocytes. These findings have direct implications for tissue engineering of cartilage tissue from stem cells and therapeutic management of OA.

Mapping molecular landmarks of human skeletal ontogeny and pluripotent stem cell-derived articular chondrocytes

Tissue-specific gene expression defines cellular identity and function, but knowledge of early human development is limited, hampering application of cell-based therapies. Here we profiled 5 distinct cell types at a single fetal stage, as well as chondrocytes at 4 stages in vivo and 2 stages during in vitro differentiation. Network analysis delineated five tissue-specific gene modules; these modules and chromatin state analysis defined broad similarities in gene expression during cartilage specification and maturation in vitro and in vivo, including early expression and progressive silencing of muscle- and bone-specific genes. Finally, ontogenetic analysis of freshly isolated and pluripotent stem cell-derived articular chondrocytes identified that integrin alpha 4 defines 2 subsets of functionally and molecularly distinct chondrocytes characterized by their gene expression, osteochondral potential in vitro and proliferative signature in vivo. These analyses provide new insight into human musculoskeletal development and provide an essential comparative resource for disease modeling and regenerative medicine.