Rotator cuff repair: an analysis of utility scores and cost-effectiveness

Value-based shoulder surgery: practicing outcomes-driven, cost-conscious care

BACKGROUND

Pathology of the shoulder contributes significantly to the increasing burden of musculoskeletal disease. Currently, there exists high variability in the nature and quality of shoulder care, and outcomes and cost reporting are not uniform. Value-based practice aims to simultaneously maximize outcomes and minimize costs for given disease processes.

METHODS

The current state of the shoulder care literature was examined with regards to cost and outcomes data, initiatives in streamlining care delivery, and evidence-based practice improvements. This was synthesized with value-based care theory to propose new avenues to improve shoulder care in the future.

CONCLUSION

The treatment of shoulder disorders is ideal for the value-based model but has been slow to adopt its principles thus far. We can begin to advance value-based practices through (1) the universal reporting of outcomes and costs, (2) integrating shoulder care across provider specialties, and (3) critically analyzing data to formulate best practices.

The science of rotator cuff tears: translating animal models to clinical recommendations using simulation analysis

PURPOSE

The purpose of this article is to review basic science studies using various animal models for rotator cuff research and to describe structural, biomechanical, and functional changes to muscle following rotator cuff tears. The use of computational simulations to translate the findings from animal models to human scale is further detailed.

METHODS

A comprehensive review was performed of the basic science literature describing the use of animal models and simulation analysis to examine muscle function following rotator cuff injury and repair in the ageing population.

RESULTS

The findings from various studies of rotator cuff pathology emphasize the importance of preventing permanent muscular changes with detrimental results. In vivo muscle function, electromyography, and passive muscle-tendon unit properties were studied before and after supraspinatus tenotomy in a rodent rotator cuff injury model (acute vs chronic). Then, a series of simulation experiments were conducted using a validated computational human musculoskeletal shoulder model to assess both passive and active tension of rotator cuff repairs based on surgical positioning.

CONCLUSION

Outcomes of rotator cuff repair may be improved by earlier surgical intervention, with lower surgical repair tensions and fewer electromyographic neuromuscular changes. An integrated approach of animal experiments, computer simulation analyses, and clinical studies may allow us to gain a fundamental understanding of the underlying pathology and interpret the results for clinical translation.

Composite growth factor supplementation strategies to enhance tenocyte bioactivity in aligned collagen-GAG scaffolds

Biomolecular environments encountered in vivo are complex and dynamic, with combinations of biomolecules presented in both freely diffusible (liquid-phase) and sequestered (bound to the extracellular matrix) states. Strategies for integrating multiple biomolecular signals into a biomimetic scaffold provide a platform to simultaneously control multiple cell activities, such as motility, proliferation, phenotype, and regenerative potential. Here we describe an investigation elucidating the influence of the dose and mode of presentation (soluble, sequestered) of five biomolecules (stromal cell-derived factor 1α [SDF-1α], platelet-derived growth factor BB [PDGF-BB], insulin-like growth factor 1 [IGF-1], basic fibroblast growth factor [bFGF], and growth/differentiation factor 5 [GDF-5]) on the recruitment, proliferation, collagen synthesis, and genomic stability of equine tenocytes within an anisotropic collagen-GAG scaffold for tendon regeneration applications. Critically, we found that single factors led to a dose-dependent trade-off between driving tenocyte proliferation (PDGF-BB, IGF-1) versus maintenance of a tenocyte phenotype (GDF-5, bFGF). We identified supplementation schemes using factor pairs (IGF-1, GDF-5) to rescue the tenocyte phenotype and gene expression profiles while simultaneously driving proliferation. These results suggest coincident application of multi-biomolecule cocktails has a significant value in regenerative medicine applications where control of cell proliferation and phenotype are required. Finally, we demonstrated an immobilization strategy that allows efficient sequestration of bioactive levels of these factors within the scaffold network. We showed sequestration can lead to a greater sustained bioactivity than soluble supplementation, making this approach particularly amenable to in vivo translation where diffusive loss is a concern and continuous biomolecule supplementation is not feasible.

Outcomes of rotator cuff surgery: what does the evidence tell us?

Rotator cuff disease accounts for more than 4.5 million annual visits to a physician, and more than 75,000 surgical repairs are performed a year. Surgical techniques have evolved from all open repairs to all arthroscopic repairs being the most commonly used. The purpose of this article is to review the current evidence regarding the outcomes of surgical techniques in rotator cuff surgery. Reported outcomes have been favorable with open, mini-open, and arthroscopic repairs. Recently, a committee sponsored by the AAOS published a clinical practice guideline summary regarding the management of rotator cuff tears. The guidelines touched aspects of both nonoperative and operative repair. In regard to operative repair, the committee could not recommend a modality of surgical repair (eg, arthroscopic vs open) as a superior method, citing a lack of comparative studies. The theoretical advantage of arthroscopic surgery lies in smaller soft tissue dissection and the ability to evaluate and treat the glenohumeral joint. However, no study using patient-based outcomes has shown superiority compared with open or mini-open repairs. With the method of surgical repair not changing outcomes, investigation has recently focused on optimizing bone-tendon healing in rotator cuff repair. Double-row fixation allows for a more anatomic reapproximation of the rotator cuff footprint on the greater tuberosity versus single-row and has been shown to be biomechanically superior. Despite this, no clinical studies have shown superiority of one type of repair versus the other. The AAOS committee citing similar evidence gave a weak recommendation for the use of achieving tendon-to-bone healing with double-row fixation. Transosseous-equivalent repair, which provides a high compressive force on the tendon-to-bone interface of repair, is the newest fixation method under investigation to optimize healing. The use of collagen and biologic augmentation has gained interest as researchers are attempting to optimize rotator cuff healing. There is moderate evidence against the use of porcine small intestine submucosa xenograft patches. Other commercially available collagen augments have yet to be proven as either beneficial or detrimental. Other than PRP, which has not shown to have any benefit augmenting repair, no biologic augment has been investigated clinically. Overall, rotator cuff surgery portends a good outcome for appropriately selected patients. However, there is not much high-quality evidence-based research that can be used to conclude what surgical treatments are superior or appropriate for a given patient. Future research should be aimed at identifying whether and in whom rotator cuff healing is appropriate to better identify surgical candidates as well as to determine the best surgical repair strategy.

Cost analysis in shoulder arthroplasty surgery

Cost in shoulder surgery has taken on a new focus with passage of the Patient Protection and Affordable Care Act. As part of this law, there is a provision for Accountable Care Organizations (ACOs) and the bundled payment initiative. In this model, one entity would receive a single payment for an episode of care and distribute funds to all other parties involved. Given its reproducible nature, shoulder arthroplasty is ideally situated to become a model for an episode of care. Currently, there is little research into cost in shoulder arthroplasty surgery. The current analyses do not provide surgeons with a method for determining the cost and outcomes of their interventions, which is necessary to the success of bundled payment. Surgeons are ideally positioned to become leaders in ACOs, but in order for them to do so a methodology must be developed where accurate costs and outcomes can be determined for the episode of care.

Healing rates for challenging rotator cuff tears utilizing an acellular human dermal reinforcement graft

PURPOSE

This study presents a retrospective case series of the clinical and structural outcomes (1.5 T MRI) of arthroscopic rotator cuff repair with acellular human dermal graft reinforcement performed by a single surgeon in patients with large, massive, and previously repaired rotator cuff tears.

MATERIALS AND METHODS

Fourteen patients with mean anterior to posterior tear size 3.87 ± 0.99 cm (median 4 cm, range 2.5-6 cm) were enrolled in the study and were evaluated for structural integrity using a high-field (1.5 T) MRI at an average of 16.8 months after surgery. The Constant-Murley scores, the Flexilevel Scale of Shoulder Function (Flex SF), scapular plane abduction, and strength were analyzed.

RESULTS

MRI results showed that the rotator cuff repair was intact in 85.7% (12/14) of the patients studied. Two patients had a Sugaya Type IV recurrent tear (2 of 14; 14.3%), which were both less than 1 cm. The Constant score increased from a preoperative mean of 49.72 (range 13-74) to a postoperative mean of 81.07 (range 45-92) (P value = 0.009). Flexilevel Scale of Shoulder Function (Flex SF) Score normalized to a 100-point scale improved from a preoperative mean of 53.69 to a postoperative mean of 79.71 (P value = 0.003). The Pain Score improved from a preoperative mean of 7.73 to a postoperative mean of 13.57 (P value = 0.008). Scapular plane abduction improved from a preoperative mean of 113.64° to a postoperative mean of 166.43° (P value = 0.010). The strength subset score improved from a preoperative mean of 1.73 kg to a postoperative mean of 7.52 kg (P value = 0.006).

CONCLUSIONS

This study presents a safe and effective technique that may help improve the healing rates of large, massive, and revision rotator cuff tears with the use of an acellular human dermal allograft. This technique demonstrated favorable structural healing rates and statistically improved functional outcomes in the near term.

LEVEL OF EVIDENCE

4. Retrospective case series.

Does augmentation with a reinforced fascia patch improve rotator cuff repair outcomes?

BACKGROUND

Scaffold devices are used to augment rotator cuff repairs in humans. While the strength of a novel poly-L-lactic acid-reinforced (human) fascia patch has been documented, it is unclear whether such patches will enhance the strength or likelihood of healing of rotator cuff repairs.

QUESTIONS/PURPOSES

In a canine shoulder model, we asked: Do tendon repairs augmented with a reinforced fascia patch have (1) increased biomechanical properties at Time 0 and (2) less tendon retraction and increased cross-sectional area and biomechanical properties after 12 weeks of healing compared to repairs without augmentation? (3) Do the biomechanical properties of tendon repairs reach normal values by 12 weeks of healing? And (4) is the host response associated with use of the reinforced fascia patch biocompatible?

METHODS

Eleven dogs underwent bilateral shoulder surgery with partial release and acute repair of the infraspinatus tendon, one shoulder with augmentation and one without augmentation. Repair retraction, cross-sectional area, biomechanical properties, and biocompatibility were assessed at 12 weeks.

RESULTS

At Time 0, the mean ± SD ultimate load of augmented repairs was 296 ± 130 N (46% ± 25%) more than nonaugmented repairs, with no difference in stiffness between groups. At 12 weeks, the ultimate load of augmented repairs averaged 192 ± 213 N (15% ± 16%) less than nonaugmented repairs, with no difference in stiffness between groups. At the tendon repair site at 12 weeks, the fascia patch showed a biocompatible host tissue response.

CONCLUSIONS

The biomechanical properties of repairs augmented with a reinforced fascia patch demonstrated greater ultimate load at Time 0 than nonaugmented repairs but remained essentially unchanged after 12 weeks of healing, despite improvements in the ultimate load of nonaugmented controls in the same time frame.

The cost-effectiveness of single-row compared with double-row arthroscopic rotator cuff repair

BACKGROUND

Interest in double-row techniques for arthroscopic rotator cuff repair has increased over the last several years, presumably because of a combination of literature demonstrating superior biomechanical characteristics and recent improvements in instrumentation and technique. As a result of the increasing focus on value-based health-care delivery, orthopaedic surgeons must understand the cost implications of this practice. The purpose of this study was to examine the cost-effectiveness of double-row arthroscopic rotator cuff repair compared with traditional single-row repair.

METHODS

A decision-analytic model was constructed to assess the cost-effectiveness of double-row arthroscopic rotator cuff repair compared with single-row repair on the basis of the cost per quality-adjusted life year gained. Two cohorts of patients (one with a tear of <3 cm and the other with a tear of ≥3 cm) were evaluated. Probabilities for retear and persistent symptoms, health utilities for the particular health states, and the direct costs for rotator cuff repair were derived from the orthopaedic literature and institutional data.

RESULTS

The incremental cost-effectiveness ratio for double-row compared with single-row arthroscopic rotator cuff repair was $571,500 for rotator cuff tears of <3 cm and $460,200 for rotator cuff tears of ≥3 cm. The rate of radiographic or symptomatic retear alone did not influence cost-effectiveness results. If the increase in the cost of double-row repair was less than $287 for small or moderate tears and less than $352 for large or massive tears compared with the cost of single-row repair, then double-row repair would represent a cost-effective surgical alternative.

CONCLUSIONS

On the basis of currently available data, double-row rotator cuff repair is not cost-effective for any size rotator cuff tears. However, variability in the values for costs and probability of retear can have a profound effect on the results of the model and may create an environment in which double-row repair becomes the more cost-effective surgical option. The identification of the threshold values in this study may help surgeons to determine the most cost-effective treatment.

Cost-utility analysis in spine care: a systematic review

BACKGROUND CONTEXT

Despite the importance of the information provided by cost-utility analyses (CUAs), there has been a lack of these types of studies performed in the area of spinal care.

PURPOSE

To systematically review cost-utility studies published on spinal care between 1976 and 2010.

STUDY DESIGN

Systematic review.

METHODS

All CUAs pertaining to spinal care published between 1976 and 2010 were identified using the cost-effectiveness analysis (CEA) registry database (Tufts Medical Center, Institute for Clinical Research and Health Policy) and National Health Service Economic Evaluation Database (NHS EED). The keywords used to search both the registry databases were the following: spine, spinal, neck, back, cervical, lumbar, thoracic, and scoliosis. Search of the CEA registry provided a total of 28 articles, and the NHS EED yielded an additional 5, all of which were included in this review. Each article was reviewed for the study subject, methodology, and results. Data contained within the databases for each of the 33 articles were recorded, and the manuscripts were reviewed to provide insight into the funding source, analysis perspective, discount rate, and cost-utility ratios.

RESULTS

There was wide variation among the 33 studies in methodology. There were 17 operative, 13 nonoperative, and 3 imaging studies. Study subjects included lumbar spine (n=27), cervical spine (n=4), scoliosis (n=1), and lumbar and cervical spine (n=1). Twenty-three of the studies were based on the clinical data from prospective randomized studies, 7 on decision models, 2 on prospective observational data, and 1 on a retrospective case series. Sixty cost-utility ratios were reported in the 33 articles. Of the ratios, 19 of 60 (31.6%) were cost saving, 27 of 60 (45%) were less than $100,000/quality-adjusted life year (QALY) gain, and 14 of 60 (23.3%) were greater than $100,000/QALY gain. Only four of 33 (12%) studies contained the four key criteria of cost-effectiveness research recommended by the US Panel on Cost-Effectiveness in Health and Medicine.

CONCLUSIONS

Thirty-three CUA studies and 60 cost-utility ratios have been published on various aspects of spinal care over the last 30 years. Certain aspects of spinal care have been shown to be cost effective. Further efforts, however, are needed to better define the value of many aspects of spinal care. Future CUA studies should consider societal cost perspective and carefully consider the durability of clinical benefit in determining a study time horizon.

The biomechanical role of scaffolds in augmented rotator cuff tendon repairs

BACKGROUND

Scaffolds continue to be developed and used for rotator cuff repair augmentation; however, the appropriate scaffold material properties and/or surgical application techniques for achieving optimal biomechanical performance remains unknown. The objectives of the study were to simulate a previously validated spring-network model for clinically relevant scenarios to predict: (1) the manner in which changes to components of the repair influence the biomechanical performance of the repair and (2) the percent load carried by the scaffold augmentation component.

MATERIALS AND METHODS

The models were parametrically varied to simulate clinically relevant scenarios, namely, changes in tendon quality, altered surgical technique(s), and different scaffold designs. The biomechanical performance of the repair constructs and the percent load carried by the scaffold component were evaluated for each of the simulated scenarios.

RESULTS

The model predicts that the biomechanical performance of a rotator cuff repair can be modestly increased by augmenting the repair with a scaffold that has tendon-like properties. However, engineering a scaffold with supraphysiologic stiffness may not translate into yet stiffer or stronger repairs. Importantly, the mechanical properties of a repair construct appear to be most influenced by the properties of the tendon-to-bone repair. The model suggests that in the clinical setting of a weak tendon-to-bone repair, scaffold augmentation may significantly off-load the repair and largely mitigate the poor construct properties.

CONCLUSIONS

The model suggests that future efforts in the field of rotator cuff repair augmentation may be directed toward strategies that strengthen the tendon-to-bone repair and/or toward engineering scaffolds with tendon-like mechanical properties.

The effect of tear size and nerve injury on rotator cuff muscle fatty degeneration in a rodent animal model

BACKGROUND

Irreversible muscle changes after rotator cuff tears is a well-known negative prognostic factor after shoulder surgery. Currently, little is known about the pathomechanism of fatty degeneration of the rotator cuff muscles after chronic cuff tears. The purposes of this study were to (1) develop a rodent animal model of chronic rotator cuff tears that can reproduce fatty degeneration of the cuff muscles seen clinically, (2) describe the effects of tear size and concomitant nerve injury on muscle degeneration, and (3) evaluate the changes in gene expression of relevant myogenic and adipogenic factors after rotator cuff tears using the animal model.

MATERIALS AND METHODS

Rotator cuff tears were created in rodents with and without transection of the suprascapular nerve. The supraspinatus and infraspinatus muscles were examined at 2, 8, and 16 weeks after injury for histologic evidence of fatty degeneration and expression of myogenic and adipogenic genes.

RESULTS

Histologic analysis revealed adipocytes, intramuscular fat globules, and intramyocellular fat droplets in the tenotomized and neurotomized supraspinatus and infraspinatus muscles. Changes increased with time and were most severe in the muscles with combined tenotomy and neurotomy. Adipogenic and myogenic transcription factors and markers were upregulated in muscles treated with tenotomy or tenotomy combined with neurotomy compared with normal muscles.

CONCLUSIONS

The rodent animal model described in this study produces fatty degeneration of the rotator cuff muscles similar to human muscles after chronic cuff tears. The severity of changes was associated with tear size and concomitant nerve injury.

Cost-effectiveness analysis of autologous chondrocyte implantation: a comparison of periosteal patch versus type I/III collagen membrane

BACKGROUND

Autologous chondrocyte implantation (ACI) involves the use of a periosteal patch (ACI-P) as a cover for transplanted chondrocytes. Theoretically, this periosteal patch provides mesenchymal stem cells and growth factors that encourage chondrocyte development/differentiation. However, there is a significant rate of graft hypertrophy with the use of periosteum compared with using a type I/III collagen patch (ACI-C). This type I/III collagen patch, although not approved by the United States Food and Drug Administration for ACI, has been used extensively in Europe and in an "off-label" nature in the United States as a cover during ACI.

PURPOSE

To examine the cost effectiveness of ACI and determine whether ACI-C is more cost effective than ACI-P.

STUDY DESIGN

Economic and decision analysis; Level of evidence, 2.

METHODS

Outcome data and complication rates from patients undergoing ACI (ACI-P and ACI-C) were derived from the best evidence in the literature. Costs were determined by examining the typical patient charges undergoing ACI at a local orthopaedic hospital. The costs, results, and complication rates were used to develop a decision analysis model comparing ACI-P to ACI-C.

RESULTS

The cost of ACI-P was $66,752 and for ACI-C was $66,939.50 ($187.50 difference). The cost per quality-adjusted life year (QALY) for ACI-P was $9466 compared with $9243 for ACI-C. Sensitivity analysis was performed regarding the additional cost of the type I/III collagen patch ($780) in ACI-C as well as the rate of graft hypertrophy after ACI-P (25%). This analysis revealed that the cost of the type I/III collagen patch would have to reach $1721, or the rate of graft hypertrophy after ACI-P reduced to almost 11%, before ACI-P became more cost effective than ACI-C.

CONCLUSION

This cost-effectiveness analysis reveals that, while both ACI-P and ACI-C are cost effective, ACI-C is slightly more cost effective than ACI-P. This is likely secondary to the significant rate of patch-related complications associated with ACI-P, which is significantly reduced with ACI-C. Although the model is very sensitive to differences in outcomes between ACI-P and ACI-C, there is no high-quality evidence to suggest that there is a significant difference between the two. Thus, ACI-P becomes more cost effective if the cost of the type I/III collagen membrane is significantly increased or if the rate of graft hypertrophy after ACI-P were to be markedly reduced.

Does age or bilateral disease influence the value of hip arthroplasty?

BACKGROUND

Measuring value in medicine is an increasingly important issue as healthcare spending continues to rise and cost containment becomes even more important. However, value assessments can be affected by patient factors and comorbidities.

QUESTIONS/PURPOSES

We therefore quantified the approximate value of total hip arthroplasty and determined if patient age and Charnley classification affected the EuroQol5D (EQ5D) after hip arthroplasty.

METHODS

Using charge data and an institutional joint registry, we evaluated 1442 patients after hip arthroplasty. Using the Charnley case-mix index to define bilateral disease and age of 65 years to distinguish between elderly and young patients, statistical comparisons were made among all groups. We obtained subspecialty physician charges and hospital charges.

RESULTS

Patients with both unilateral and bilateral disease in both age groups had improved EQ5D scores after total hip arthroplasty, and the average change in scores was 0.27. There was no difference in the change in utility scores when patients older than 65 years of age were compared with patients younger than 65 years or when patients with unilateral disease were compared with those with bilateral disease. The average cost per quality-adjusted life-year (QALY) gained was $9773/QALY.

CONCLUSIONS

Our data suggest the value of total hip arthroplasty compares favorably with other medical and surgical interventions for other patient groups. No adjustments for patient age or disease status of the contralateral limb are necessary when reporting the value of total hip arthroplasty.

LEVEL OF EVIDENCE

Level IV, economic and decision analyses study. See Guidelines for Authors for a complete description of levels of evidence.

Full thickness tears: retaining the cuff

Repair of rotator cuff tears is technically challenging. Full thickness rotator cuff tears have no potential for spontaneous healing, no reliable tendons substitutes are available, and their management is only partially understood. Many factors seem to contribute to the final outcome, and considerable variations in the decision-making process exist. For these reasons, decisions are often taken on the basis of surgeon's clinical experience. Accurate and prompt diagnosis is fundamental to guide correct management, and the tear pattern should be carefully evaluated to planning the most appropriate repair.

Evaluation of utility in shoulder pathology: Correlating the American Shoulder and Elbow Surgeons and Constant scores to the EuroQoL

AIM: To study whether health utility scores can be derived from shoulder-specific scores.

METHODS: Authors investigated two questions: (1) do the American Shoulder and Elbow Surgeons (ASES) score and the Constant score correlate with the EuroQoL (EQ-5D), a measure of health utility? (2) can the ASES and Constant scores be obtained from a complete study sample without bias? Thirty subjects with various shoulder diagnoses completed ASES, Constant, and EQ-5D instruments. Pearson correlations were calculated to assess the associations between EQ-5D score and ASES and Constant scores.

RESULTS: The correlation between EQ-5D score and ASES score was 0.60 (P < 0.001); it was 0.54 for EQ-5D and Constant scores (P < 0.003). A multiple regression model containing ASES score, Constant score, age, and gender failed to adequately predict EQ-5D. Moreover, 25% of patients meeting the inclusion criteria did not complete the ASES questionnaire because they did not feel that specific questions, such as “do usual sport - list” and “throw ball overhand,” applied to them.

CONCLUSION: Authors’ results do not support the use of the ASES and Constant scores in predicting EuroQol health utility values. However, the Constant score was more suitable for this patient population because all patients were able to complete it.

Quality of life after arthroscopic rotator cuff repair: evaluation using SF-36 and an analysis of affecting clinical factors

BACKGROUND

Despite its importance, few studies regarding health-related quality of life (HRQOL) after rotator cuff repair have been reported.

PURPOSE

To evaluate the outcomes of rotator cuff repair in terms of HRQOL using SF-36 and to analyze factors affecting postoperative HRQOL.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We included 309 patients who were followed-up for a mean 26.3 months (range, 12-48 months) after arthroscopic rotator cuff repair, between November 2004 and August 2008, and who underwent periodic measurement of HRQOL using SF-36 preoperatively, 1 year postoperatively, and at the final follow-up. The correlation between SF-36 and shoulder-specific functional outcome measures (American Shoulder and Elbow Surgeons [ASES], Simple Shoulder Test [SST], and Constant score) was evaluated using correlation analysis, and the relationship between various clinical factors, including rotator cuff healing and HRQOL, was assessed using univariate and multivariate analyses.

RESULTS

The SF-36 scores for physical HRQOL and mental HRQOL showed significant improvement, from 40.40 to 47.53 and from 44.45 to 50.55 at 12 months after surgery, respectively (all P < .001), and improvement was maintained with 48.24 and 50.45, respectively, at the final follow-up (all P < .001). Scores also showed improvement according to all clinical variables, even after stratification of each variable. The correlation between SF-36 and shoulder-specific functional outcome measures was fair to moderate (Pearson correlation coefficients, 0.199-0.528). Various factors had significant effects on preoperative physical and mental HRQOL; however, postoperatively (at 12 months and final follow-up, respectively), only older age (P = .008 and .013), female sex (P = .036 and .043), presence of diabetes (P = .026 and .027), and low level of sports activity (P = .049 at final follow-up) had a negative effect on postoperative physical HRQOL in multivariate analysis, and female sex (P = .010 and .001) was the only factor leading to worse postoperative mental HRQOL.

CONCLUSION

Arthroscopic rotator cuff repair significantly improved the patients' HRQOL both physically and mentally. Older age, female sex, diabetes, and low level of sports activity were related to low postoperative physical HRQOL, and female sex was also related to low postoperative mental HRQOL.

Economic evaluations in shoulder pathologies: a systematic review of the literature

BACKGROUND

Economic evaluations provide decision makers with a tool for reducing health care costs because they assess both the costs and consequences of health care interventions. This study reviewed the quality of published economic evaluations for shoulder pathologies.

MATERIALS AND METHOD

A MEDLINE search was conducted to identify articles published from 1980 to 2010 that contained "cost" or "economic" combined with terms for several shoulder disorders and treatments. We selected studies that fit the definition of 1 of the 4 routinely performed economic evaluations: cost-minimization, cost-effectiveness, cost-utility, and cost-benefit analyses. Study quality was determined by measuring adherence to 6 established health economic principles, as described in the literature.

RESULTS

The search retrieved 942 studies. Of these, 32 were determined to be economic evaluations, and 53% of the economic evaluations were published from 2005 to 2010. Only 8 of the 32 studies (25%) adhered to all 6 health economic principles. Publication in a nonsurgical journal (P < .05) or in more recent years (P < .01) was significantly associated with higher quality.

CONCLUSION

Future health care resource allocation will likely be based on the economic feasibility of treatments. Although the number and quality of economic evaluations of shoulder disorders have risen in recent years, the current state of the literature is poor. Given that availability of such data may factor in private and public reimbursement decisions, there is a clear demand for more rigorous economic evaluations.

Scaffold devices for rotator cuff repair

Rotator cuff tears affect 40% or more of those aged older than 60 years, and repair failure rates of 20% to 70% remain a significant clinical challenge. Hence, there is a need for repair strategies that can augment the repair by mechanically reinforcing it, while at the same time biologically enhancing the intrinsic healing potential of the tendon. Tissue engineering strategies to improve rotator cuff repair healing include the use of scaffolds, growth factors, and cell seeding, or a combination of these approaches. Currently, scaffolds derived from mammalian extracellular matrix, synthetic polymers, and a combination thereof, have been cleared by the U.S. Food and Drug Administration and are marketed as medical devices for rotator cuff repair in humans. Despite the growing clinical use of scaffold devices for rotator cuff repair, there are numerous questions related to their indication, surgical application, safety, mechanism of action, and efficacy that remain to be clarified or addressed. This article reviews the current basic science and clinical understanding of commercially available synthetic and extracellular matrix scaffolds for rotator cuff repair. Our review will emphasize the host response and scaffold remodeling, mechanical and suture-retention properties, and preclinical and clinical studies on the use of these scaffolds for rotator cuff repair. We will discuss the implications of these data on the future directions for use of these scaffolds in tendon repair procedures.

Fiber-aligned polymer scaffolds for rotator cuff repair in a rat model

BACKGROUND

Repair techniques of rotator cuff tendon tears have improved in recent years; nonetheless, the failure rate remains high. Despite the availability of various graft materials for repair augmentation, there has yet to be a biomechanical study using fiber-aligned scaffolds in vivo. The objective of this study was to evaluate the efficacy of fiber-aligned nanofibrous polymer scaffolds as a potential treatment-delivery vehicle in a rat rotator cuff injury model.

MATERIALS AND METHODS

Scaffolds with and without sacrificial fibers were fabricated via electrospinning and implanted to augment supraspinatus repair in rats. Repairs without scaffold augmentation were also performed to serve as controls. Rats were sacrificed at 4 and 8 weeks postoperatively, and repairs were evaluated histologically and biomechanically.

RESULTS

Both scaffold formulations remained in place, with more noticeable cellular infiltration and colonization at 4 and 8 weeks after injury and repair for scaffolds lacking sacrificial fibers. Specimens with scaffolds were larger in cross-sectional area compared with controls. Biomechanical testing revealed no significant differences in structural properties between the groups. Some apparent material properties were significantly reduced in the scaffold groups. These reductions were due to increases in cross-sectional area, most likely caused by the extra thickness of the implanted scaffold material. No differences were observed between the 2 scaffold groups.

CONCLUSIONS

No adverse effect of surgical implantation of overlaid fiber-aligned scaffolds on structural properties of supraspinatus tendons in rat rotator cuff repair was demonstrated, validating this model as a platform for targeted delivery.

Measurement of in vivo tendon function

Chronic tendon pathologies (eg, rotator cuff tears, Achilles tendon ruptures) are common, painful, debilitating, and a significant source of medical expense. Treatment strategies for managing tendon pathologies vary widely in invasiveness and cost, with little scientific basis on which to base treatment selection. Conventional techniques for assessing the outcomes of physical therapy or surgical repair typically rely on patient-based assessments of pain and function, physical measures (eg, strength, range of motion, or stability), and qualitative assessments using magnetic resonance imaging or ultrasound. Unfortunately, these conventional techniques provide only an indirect assessment of tendon function. The inability to make a direct quantitative assessment of the tendon's mechanical capabilities may help to explain the relatively high rate of failed tendon repairs and has led to an interest in the development of tools for directly assessing in vivo tendon function. The purpose of this article is to review methods for assessing tendon function (ie, mechanical properties and capabilities) during in vivo activities. This review will describe the general principles behind the experimental techniques and provide examples of previous applications of these techniques. In addition, this review will characterize the advantages and limitations of each technique, along with its potential clinical utility. Future efforts should focus on developing broadly translatable technologies for quantitatively assessing in vivo tendon function. The ability to accurately characterize the in vivo mechanical properties of tendons would improve patient care by allowing for the systematic development and assessment of new techniques for treating tendon pathologies.

Basic mechanisms of tendon fatigue damage

Pathologic processes intrinsic and extrinsic to the tendons have been proposed as the underlying cause of rotator cuff disease, but the precise etiology is not known. Tear formation is, in part, attributable to the accumulation of subrupture tendon fatigue damage. We review the molecular, mechanical, and structural changes induced in tendons subjected to controlled amounts of fatigue loading in an animal model of early tendinopathy. The distinct tendon responses to low and moderate levels of loading, as opposed to high levels, provide insight into the potential mechanisms for the therapeutic benefits of exercise in the treatment of rotator cuff tendinopathy. The progression of damage accumulation leading to fiber rupture and eventual tendon tearing seen with higher loading illustrates the progression from tendinopathy to full-thickness tearing. We hope that this more realistic animal model of tendon fatigue damage will allow better assessment of biologic, mechanical, tissue-engineering, and rehabilitation strategies to improve repair success.

Tissue-engineering strategies for the tendon/ligament-to-bone insertion

Injuries to connective tissues are painful and disabling and result in costly medical expenses. These injuries often require reattachment of an unmineralized connective tissue to bone. The uninjured tendon/ligament-to-bone insertion (enthesis) is a functionally graded material that exhibits a gradual transition from soft tissue (i.e., tendon or ligament) to hard tissue (i.e., mineralized bone) through a fibrocartilaginous transition region. This transition is believed to facilitate force transmission between the two dissimilar tissues by ameliorating potentially damaging interfacial stress concentrations. The transition region is impaired or lost upon tendon/ligament injury and is not regenerated following surgical repair or natural healing, exposing the tissue to risk of reinjury. The need to regenerate a robust tendon-to-bone insertion has led a number of tissue engineering repair strategies. This review treats the tendon-to-bone insertion site as a tissue structure whose primary role is mechanical and discusses current and emerging strategies for engineering the tendon/ligament-to-bone insertion in this context. The focus lies on strategies for producing mechanical structures that can guide and subsequently sustain a graded tissue structure and the associated cell populations.

Biologic and pharmacologic augmentation of rotator cuff repairs

As rotator cuff repair techniques have improved, failure of the tendon to heal to the proximal humerus is less likely to occur from weak tendon-to-bone fixation. More likely causes of failure include biologic factors such as intrinsic tendon degeneration, fatty atrophy, fatty infiltration of muscle, and lack of vascularity of the tendons. High failure rates have led to the investigation of biologic augmentation to potentially enhance the healing response. Histologic studies have shown that restoration of the rotator cuff footprint during repair can help reestablish the enthesis. In animal models, growth factors and their delivery scaffolds as well as tissue engineering have shown promise in decreasing scar tissue while maintaining biomechanical strength. Platelet-rich plasma may be a safe adjuvant to rotator cuff repair, but it has not been shown to improve healing or function. Many of these strategies need to be further defined to permit understanding of, and to optimize, the biologic environment; in addition, techniques need to be refined for clinical use.

Common generic measures of health related quality of life in injured patients

The measurement of health-related quality of life (HRQOL) through generic outcome instruments is important for comparisons of populations across disease states and interventions. The growing number of questionnaires available has made selection and interpretation more difficult. Profile instruments such as the SF-36 and Sickness Impact Profile provide insight into various domains of health with established population norms. Preference-based measures, including the EQ-5D, Health Utilities Index, SF-6D, and QWB-SA are used to generate utility scores, which can be used for cost-effectiveness analysis and therefore have particular relevance in health policy. Both types of generic measures have been used in clinical trials in injured populations to assess the relative impact of interventions on quality-of-life. Comparisons of internal consistency and test-retest reliability across measures reveal minimal differences between instruments, and reported values are acceptable for group comparisons but insufficient for individual clinical use. There is a dearth of studies evaluating the validity of these measures in the trauma population, but available data suggest most of the available instruments are acceptable. Populations that may require special consideration are patients with head, spinal cord, and upper-extremity injuries. Practical issues to consider in selecting a questionnaire include time for completion, which ranges from less than 2 min for the EQ-5D to 20-30 min for the Sickness Impact Profile. Selection of the appropriate measure ultimately depends largely on the population to be studied and whether utility-estimation is desired.

An analytical model for rotator cuff repairs

BACKGROUND

Currently, natural and synthetic scaffolds are being explored as augmentation devices for rotator cuff repair. When used in this manner, these devices are believed to offer some degree of load sharing; however, no studies have quantified this effect. Furthermore, the manner in which loads on an augmented rotator cuff repair are distributed among the various components of the repair is not known, nor is the relative biomechanical importance of each component. The objectives of this study are to (1) develop quasi-static analytical models of simplified rotator cuff repairs, (2) validate the models, and (3) predict the degree of load sharing provided by an augmentation scaffold.

METHODS

The individual components of the repair constructs were modeled as non-linear springs, and the model equations were formulated based on the physics of springs in series and parallel. The model was validated and used to predict the degree of load sharing provided by a scaffold. Parametric sensitivity analysis was used to identify which of the component(s)/parameter(s) most influenced the mechanical behavior of the augmented repair models.

FINDINGS

The validated models predict that load will be distributed approximately 70-80% to the tendon repair and approximately 20-30% to the augmentation component. The sensitivity analysis suggests that the greatest improvements in the force carrying capacity of a tendon repair may be achieved by improving the properties of the bone-suture-tendon interface. Future studies will perform parametric simulation to illustrate the manner in which changes to the individual components of the repair, representing different surgical techniques and scaffold devices, may influence the biomechanics of the repair construct.

Nonoperative treatment of superior labrum anterior posterior tears: improvements in pain, function, and quality of life

BACKGROUND

Although there are multiple reports documenting successful outcomes with operative treatment of superior labrum anterior posterior (SLAP) tears, there are few reports on the results of nonoperative treatment.

HYPOTHESIS

Nonoperative treatment of SLAP tears will result in improved outcomes over pretreatment values using validated, patient-derived outcome instruments.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 371 patients with a diagnosis of labral tear at our institution were mailed a questionnaire that included the following validated, patient-derived outcome assessment instruments: Short Form 36 (SF-36), European Quality of Life measure (EuroQol), visual analog pain scale (VAS), American Shoulder and Elbow Surgeons (ASES) score, and simple shoulder test (SST). Sixty-six surveys did not reach the patients because of incorrect addresses, and 50 surveys were returned, for a 16.4% (50 of 305) response rate. Of the patients with a clinically documented SLAP lesion (positive O'Brien test, pain at the bicipital groove, and positive magnetic resonance imaging) and sufficient follow-up data (minimum 1 year), 39 patients who met the criteria returned the survey and 19 had nonoperative treatment. Twenty patients (51%) from the overall surveyed group were considered nonoperative treatment failures and had arthroscopic surgical reconstruction. Nonoperative treatment consisted of nonsteroidal anti-inflammatory drugs and a physical therapy protocol focused on scapular stabilization exercises and posterior capsular stretching. Statistical analysis was performed using the paired t test; values of P < .05 were considered significant.

RESULTS

At an average follow-up of 3.1 years, function improved significantly (ASES function 30.8 to 45.0 [P < .001]; ASES total 58.5 to 84.7 [P = .001], SST 8.3 to 11.0 [P = .02]) in those patients with successful nonoperative treatment. Quality of life also improved after treatment (EuroQol 0.76 to 0.89, P = .009). Pain relief was significant, as VAS pain scores decreased from 4.5 to 2.1 (P = .043). All patients with successful nonoperative treatment returned to sports. Seventy-one percent of all athletes were able to return to preparticipation levels, but only 66% of overhead athletes returned to their sport at the same or higher level.

CONCLUSION

Using validated, patient-derived outcome instruments, the present study shows that successful nonoperative treatment of superior labral tears results in improved pain relief and functional outcomes compared with pretreatment assessments. Although 20 patients (51%) in this group elected surgery and may be considered nonoperative treatment failures, those patients with successful nonoperative treatment had significant improvements in pain, function, and quality of life. Return to sports was comparable with patients with successful surgical treatment, although return to overhead sports at the same level was difficult to achieve (66%). Based on these findings, a trial of nonoperative treatment may be considered in patients with the diagnosis of isolated superior labral tear. In overhead athletes and in those patients where pain relief and functional improvement is not achieved, surgical treatment should be considered.

Stem cells genetically modified with the developmental gene MT1-MMP improve regeneration of the supraspinatus tendon-to-bone insertion site

BACKGROUND

Rotator cuffs heal through a scar tissue interface after repair, which makes them prone to failure. Membrane type 1 matrix metalloproteinase (MT1-MMP) is upregulated during embryogenesis in areas that develop into tendon-bone insertion sites.

HYPOTHESIS

Bone marrow-derived stem cells in the presence of the developmental signal from MT1-MMP will drive the healing process toward regeneration and away from scar formation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sixty Lewis rats underwent unilateral detachment and repair of the supraspinatus tendon. Thirty animals received mesenchymal stem cells (MSCs) in a fibrin glue carrier, and 30 received adenoviral MT1-MMP (Ad-MT1-MMP)-transduced MSCs. Animals were sacrificed at 2 weeks and 4 weeks and evaluated for the presence of fibrocartilage and collagen fiber organization at the insertion. Biomechanical testing was performed to determine the structural and material properties of the repaired tissue. Statistical analysis was performed with a Wilcoxon rank-sum test with significance set at P = .05.

RESULTS

There were no differences between the Ad-MT1-MMP and MSC groups in any outcome variable at 2 weeks. At 4 weeks, the Ad-MT1-MMP group had more fibrocartilage (P = .05), higher ultimate load to failure (P = .01), higher ultimate stress to failure (P = .005), and higher stiffness values (P = .02) as compared with the MSC group.

CONCLUSION

Mesenchymal stem cells genetically modified to overexpress the developmental gene MT1-MMP can augment rotator cuff healing at 4 weeks by the presence of more fibrocartilage at the insertion and improved biomechanical strength.

CLINICAL RELEVANCE

Biologic augmentation of repaired rotator cuffs with MT1-MMP-transduced MSCs may reduce the incidence of retears. However, further studies are needed to determine if this remains safe and effective in larger models.

Total cost and operating room time comparison of rotator cuff repair techniques at low, intermediate, and high volume centers: mini-open versus all-arthroscopic

BACKGROUND

The objective of this study was to determine mean cost and operative time differences between mini-open and all-arthroscopic rotator cuff repair techniques at surgical centers of low, intermediate, and high annual rotator cuff repair volume.

METHODS

The 2006 New York State Ambulatory Surgery Database (NY-SASD) was utilized. It represents 100% of all outpatient procedures performed in hospital-affiliated and freestanding surgical centers, containing 10,658,923 patients for 2006 alone. Only patients who had an arthroscopic acromioplasty and either open or arthroscopic rotator cuff repair were included, leaving 5,224 patients for the study. These were divided into 2 groups: the mini-open group (1,334) and the all-arthroscopic group (3,890). Surgical center volume data were divided into 3 groups: low volume (<75 rotator cuff repairs per year), intermediate volume (75-199 rotator cuff repairs per year), and high volume (200+ rotator cuff repairs per year).

RESULTS

Patient age and gender were normally distributed within the 2 groups with no significant differences between them (P = .82 and P = .31, respectively). Operative time was significantly shorter in the mini-open group (103 minutes) compared to the all-arthroscopic group (113 minutes), P < .00001. Surgical charges were also significantly less in the mini-open group ($7,841) compared to the all-arthroscopic group ($8,985), P < .00001. Regardless of the repair method, high volume surgical centers were significantly more expensive when compared to low and intermediate volume centers, P < .00001.

CONCLUSION

The mini-open rotator cuff repair technique requires significantly less operative time and is significantly less expensive than the all-arthroscopic repair. Regardless of the repair technique, high volume surgical centers cost significantly more than low and intermediate volume surgical centers.

Improved time-zero biomechanical properties using poly-L-lactic acid graft augmentation in a cadaveric rotator cuff repair model

HYPOTHESIS

Rotator cuff repair failure rates range from 20% to 90%, and failure is believed to occur most commonly by sutures cutting through the tendon due to excessive tension at the repair site. This study was designed to determine whether application of a woven poly-L-lactic acid device (X-Repair; Synthasome, San Diego, CA) would improve the mechanical properties of rotator cuff repair in vitro.

MATERIALS AND METHODS

Eight pairs of human cadaveric shoulders were used to test augmented and non-augmented rotator cuff repairs. Initial stiffness, yield load, ultimate load, and failure mode were compared.

RESULTS

Yield load was 56% to 92% higher and ultimate load was 56% to 76% higher in augmented repairs. No increase in initial stiffness was found. Failure by sutures cutting through the tendon was reduced, occurring in 17 of 20 non-augmented repairs but only 7 of 20 augmented repairs.

CONCLUSIONS

Our data show that application of the X-Repair device significantly increased the yield load and ultimate load of rotator cuff repairs in a human cadaveric model and altered the failure mode but did not affect initial repair stiffness.

The effect of the trabecular microstructure on the pullout strength of suture anchors

This study investigates how the microstructural properties of trabecular bone affect suture anchor performance. Seven fresh-frozen humeri were tested for pullout strength with a 5mm Arthrex Corkscrew in the greater tuberosity, lesser tuberosity, and humeral head. Micro-computed tomography analysis was performed in the three regions of interest directly adjacent to individual pullout experiments. The morphometric properties of bone mineral density (BMD), structural model index (SMI), trabecular thickness (TbTh), trabecular spacing (TbS), trabecular number (TbN), and connectivity density were compared against suture anchor pullout strength. BMD (r=0.64), SMI (r=-0.81), and TbTh (r=0.71) showed linear correlations to the pullout strength of the suture anchor with p-values<0.0001. A predictive model was developed to explain the variances in the individual BMD, SMI, and TbTh correlations. The multi-variant model of pullout strength showed a stronger relationship (r=0.86) compared to the individual experimental results. This study helps confirm BMD is a major influence on the pullout strength of suture anchors, but also illustrates the importance of local microstructure in pullout resistance of suture anchors.

Extracellular matrix scaffold devices for rotator cuff repair

Rotator cuff tears affect 40% or more of those over age 60, and the repair failure rate of large to massive tears ranges from 20 to 90%. High re-tear rates are a result of mechanical factors as well as biologic factors that may compromise the patients' intrinsic capacity to heal. Hence, there is a critical need for repair strategies that provide adequate strength as well as stimulate and enhance healing potential. Tissue engineering strategies to improve rotator cuff repair healing include the use of scaffolds, growth factors, cell seeding or a combination of these approaches. Scaffolds have been the most common strategy investigated to date. Despite the growing clinical use of scaffold devices for rotator cuff repair, there are numerous questions related to their indication, surgical application, safety, mechanism of action and efficacy that remain to be clarified or addressed. The purpose of this paper is to review the current basic science and clinical understanding of extracellular matrix scaffolds, which are currently the most widely used scaffolds for rotator cuff repair. Our review will emphasize the host immune response and scaffold remodeling, the mechanical and suture retention properties of ECMs and preclinical and clinical studies on the use of ECMs for rotator cuff repair. We will then discuss the implications of these data on the future directions for use of these scaffolds in tendon repair procedures.

Cost-effectiveness of open versus arthroscopic rotator cuff repair

BACKGROUND

Economic evaluation of surgical procedures is necessary in view of more expensive newer techniques emerging in an increasingly cost-conscious health care environment. This study compares the cost-effectiveness of open rotator cuff repair with arthroscopic repair for moderately size tears.

MATERIALS AND METHODS

This was a prospective study of 30 consecutive patients, of whom 15 had an arthroscopic repair and 15 had an open procedure. Clinical effectiveness was assessed using Oxford and Constant shoulder scores. Costs were estimated from departmental and hospital financial data.

RESULTS

At last follow-up, no difference Oxford and Constant shoulder scores was noted between the 2 methods of repair. There was no significant difference between the groups in the cost of time in the operating theater, inpatient time, amount of postoperative analgesia, number of postoperative outpatient visits, physiotherapy costs, and time off work. The incremental cost of each arthroscopic rotator cuff repair was pound675 ($1248.75) more than the open procedure. This was mainly in the area of direct health care costs, instrumentation in particular.

DISCUSSION

Health care policy makers are increasingly demanding evidence of cost-effectiveness of a procedure. This study showed both methods of repair provide equivalent clinical results.

CONCLUSION

Open cuff repair is more cost-effective than arthroscopic repair and is likely to have lower cost-utility ratio. In addition, the tariff for the arthroscopic procedure in some health care systems is same as open repair.

Cost-effectiveness of postural exercise therapy versus physiotherapy in computer screen-workers with early non-specific work-related upper limb disorders (WRULD); a randomized controlled trial

Background

Exercise therapies generate substantial costs in computer workers with non-specific work-related upper limb disorders (WRULD).

Aims

To study if postural exercise therapy is cost-effective compared to regular physiotherapy in screen-workers with early complaints, both from health care and societal perspective.

Methods

Prospective randomized trial including cost-effectiveness analysis; one year follow-up. Participants: Eighty-eight screen-workers with early non-specific WRULD; six drop-outs. Interventions: A ten week postural exercise program versus regular physiotherapy. Outcome measures: Effectiveness measures: Pain: visual analogous scale (VAS), self-perceived WRULD (yes/no). Functional outcome: Disabilities of Arm, Shoulder and Hand- Dutch Language Version (DASH-DLV). Quality of life outcome: EQ-5D.

Economic measures: health care costs including patient and family costs and productivity costs resulting in societal costs. Cost-effectiveness measures: health care costs and societal costs related to the effectiveness measures. Outcome measures were assessed at baseline; three, six and twelve months after baseline.

Results

At baseline both groups were comparable for baseline characteristics except scores on the Pain Catastrophizing Scale and comparable for costs. No significant differences between the groups concerning effectiveness at one year follow-up were found. Effectiveness scores slightly improved over time. After one year 55% of participants were free of complaints. After one year the postural exercise group had higher mean total health care costs, but lower productivity costs compared to the physiotherapy group. Mean societal costs after one year (therefore) were in favor of postural exercise therapy [- €622; 95% CI -2087; +590)]. After one year, only self- perceived WRULD seemed to result in acceptable cost-effectiveness of the postural exercise strategy over physiotherapy; however the probability of acceptable cost-effectiveness did not exceed 60%.

Considering societal costs related to QALYs, postural exercise therapy had a probability of over 80% to be cost-effective over a wide range of cost-effectiveness ceiling ratios; however based on a marginal QALY-difference of 0.1 over a 12 month time frame.

Conclusion

Although our trial failed to find significant differences in VAS, QALYs and ICERs based on VAS and QALYs at one-year follow-up, CEACs suggest that postural exercise therapy according to Mensendieck/Cesar has a higher probability of being cost-effective compared to regular physiotherapy; however further research is required.

Trial registration

ISRCTN 15872455

Bearing area: a new indication for suture anchor pullout strength?

Studies performed to quantify the pullout strength of suture anchors have not adequately defined the basic device parameters that control monotonic pullout. The bearing area of a suture anchor can be used to understand and predict anchor pullout strength in a soft-bone model. First, conical-shaped test samples were varied in size and shape and tested for pullout in 5, 8, and 10 pcf sawbone models. Next, bearing area and pullout strength relationships developed from the test samples were validated against nine commercially available suture anchors, including the Mitek QuickAnchor and SpiraLok, Opus Magnum(2), ArthroCare ParaSorb, and Arthrex BioCorkscrew. The samples showed a direct correlation between bearing area and pullout strength. Increased insertion depth was a secondary condition that also increased pullout strength. The pullout strength for the suture anchors followed the predicted trends of conical devices based on their individual bearing areas. For the 5 and 8 pcf models, only two and three devices, respectively, fell outside the predicted pullout strength range by more than a standard deviation. The use of a synthetic sawbone model was validated against the pullout strength of an Arthrex Corkscrew in five fresh-frozen cadaver humeral heads. The bearing area of a suture anchor can be used to predict the pullout strength independent of design in a soft-bone model. This work helps provide a foundation to understand the principles that affect the pullout strength of suture anchors.

Novel nanofiber-based scaffold for rotator cuff repair and augmentation

The debilitating effects of rotator cuff tears and the high incidence of failure associated with current grafts underscore the clinical demand for functional solutions for tendon repair and augmentation. To address this challenge, we have designed a poly(lactide-co-glycolide) (PLGA) nanofiber-based scaffold for rotator cuff tendon tissue engineering. In addition to scaffold design and characterization, the objective of this study was to evaluate the attachment, alignment, gene expression, and matrix elaboration of human rotator cuff fibroblasts on aligned and unaligned PLGA nanofiber scaffolds. Additionally, the effects of in vitro culture on scaffold mechanical properties were determined over time. It has been hypothesized that nanofiber organization regulates cellular response and scaffold properties. It was observed that rotator cuff fibroblasts cultured on the aligned scaffolds attached along the nanofiber long axis, whereas the cells on the unaligned scaffold were polygonal and randomly oriented. Moreover, distinct integrin expression profiles on these two substrates were observed. Quantitative analysis revealed that cell alignment, distribution, and matrix deposition conformed to nanofiber organization and that the observed differences were maintained over time. Mechanical properties of the aligned nanofiber scaffolds were significantly higher than those of the unaligned, and although the scaffolds degraded in vitro, physiologically relevant mechanical properties were maintained. These observations demonstrate the potential of the PLGA nanofiber-based scaffold system for functional rotator cuff repair. Moreover, nanofiber organization has a profound effect on cellular response and matrix properties, and it is a critical parameter for scaffold design.

Comparative evaluation of the tendon-bone interface contact pressure in different single- versus double-row suture anchor repair techniques

The aim of the study was to evaluate the time zero contact pressure over a defined rotator cuff footprint using different repair and stitch techniques in an established sheep model. Forty fresh-frozen sheep shoulders were randomly assigned to five repair groups: single-row repair using simple stitches (SRA-s), single-row repair using horizontal mattress stitches (SRA-m), and single-row repair using arthroscopic Mason-Allen stitches (SRA-ama). Double-row repair was either performed with a combination of simple and horizontal mattress stitches (DRA-sm) or with arthroscopic Mason-Allen/horizontal mattress stitches (DRA-amam). Investigations were performed using a pressure-sensitive film system. The average contact pressure and pressure pattern were measured for each group. Contact pressure was lowest in SRA-m followed by SRA-s. SRA-ama showed highest contact pressure of all single-row treatment groups (P < 0.05). DRA-amam presented the highest overall contact pressure (P < 0.05), whereas DRA-sm exerted contact pressure equal to that of SRA-ama. Both double-row techniques showed the most expanded pressure pattern. Average contact pressures for the more complex single- and double-row techniques utilizing arthroscopic Mason-Allen stitches were greater than were those of the repair techniques utilizing simple and horizontal mattress stitches. However, the contact pattern between the anchors could be increased by using the double-row technique, resulting in more footprint coverage compared to patterns utilizing the single-row techniques. These results support the use of the more complex arthroscopic Mason-Allen stitches and may improve the environment for healing of the repaired rotator cuff tendon.