Rotator Cuff Tendon Repair Research Articles

Erratum to: What Influence Does Progression of a Nonhealing Rotator Cuff Tear Have on Shoulder Pain and Function?

Jeon and colleagues would like to correct an error found in the Discussion section of the published study “What Influence Does Progression of a Nonhealing Rotator Cuff Tear Have on Shoulder Pain and Function?” A sentence in the Discussion section did not accurately convey the results of the study. The sentence should be: “Patients without healing of the repaired rotator cuff tendon with a decrease in the size of their tear, as measured at 6 months after surgery, experienced better shoulder function and muscle strength from those with increased tear size when followed beyond 6 months.” The authors apologize for the error.

Migration of Mesenchymal Stem Cells of Bursal Tissue after Rotator Cuff Repair in Rats.

Purpose The purpose of this study is to verify migration of mesenchymal stem cells of bursal tissue into the healing site after rotator cuff repair in rats. Methods Fischer rats and green fluorescent protein (GFP)-transgenic rats were used. Bursal tissue from GFP rats was isolated and transplanted into tendon repair sites in Fischer rats. We examined the histology of the rotator cuff and the proportion of GFP-positive cells in the repaired rotator cuff 1, 3, and 6 weeks after surgery. Results Cell migration was observed during the third and sixth week after surgery. We also found mesenchymal stem cells and formed bursal cluster patterns in the repaired rotator cuff tendons. Conclusion Mesenchymal stem cells migrated from bursal tissue and infiltrated the repaired rotator cuff tendons. Clinical Relevance Mesenchymal stem cells from bursal tissue can contribute to the healing progress of the repaired rotator cuff.

Biomechanical, Histologic, and Molecular Evaluation of Tendon Healing in a New Murine Model of Rotator Cuff Repair

To develop a clinically relevant, robust murine model of rotator cuff tendon repair to examine cellular and molecular mechanisms of healing. Sixty C57BL/6 male mice underwent rotator cuff transection and repair using microsurgical techniques. A modified Kessler suturing technique was used prior to tendon detachment. Sutures were passed through 2 intersecting bone tunnels that were made at the tendon attachment site. Mice were sacrificed at 2 and 4weeks with subsequent biomechanical, histologic, micro-CT, and gene expression evaluations. Failure forces in the 2- and 4-week groups were 36% and 75% of the intact tendon, respectively. Histologic evaluation revealed complete reattachment of the tendon with no observable gap. Healing occurred by formation of fibrovascular tissue at the tendon-bone interface, similar to larger animal models. Molecular analysis revealed gene expression consistent with gradual healing of the reattached tendon over a period of 4weeks. Comparisons were made using 1-way analysis of variance. This model is distinguished by use of microsurgical suturing techniques, which provides a robust, reproducible, and economic animal model to study various aspects of rotator cuff pathology. Improvement of clinical outcomes of rotator cuff pathology requires in-depth understanding of the underlying cellular and molecular mechanisms of healing. This study presents a robust murine model of supraspinatus repair to serve as a standard research tool for basic and translational investigations into signaling pathways, gene expression, and the effect of biologic augmentation approaches.

Comparison of Two Arthroscopic Coracoplasty Approaches in Subscapularis Tears

BACKGROUND: Few studies have reported the results of arthroscopic coracoplasty concomitantly conducted with subscapularis tear. Therefore, this study was conducted to examine and compare the outcomes of arthroscopic subscapularis repair after arthroscopic coracoplasty using either the subacromial approach or rotator interval approach.METHODS: We retrospectively reviewed 51 patients who underwent coracoplasty with subscapularis repair. The patients were grouped according to whether the subacromial approach group (24 patients) or rotator interval approach group (27 patients) was used during coracoplasty. Preoperative and postoperative visual analogue scale scores, American shoulder and elbow surgeons scores, Korean shoulder scores, and range of motion (ROM) were assessed. Assessment of repaired rotator cuff tendon integrity was performed at 1 year after surgery using either magnetic resonance imaging or ultrasonography.RESULTS: At final follow-up, overall functional scores and ROM improved significantly in both groups when compared with preoperative values (p>0.05). The re-tear rates were not significantly different between groups; however, the rotator interval approach group showed a significant increase in ROM compared with that in the subacromial approach group (p<0.05).CONCLUSIONS: Arthroscopic coracoplasty conducted concomitantly with subscapularis repair can provide a satisfactory outcome. There were no significant differences between the two approach groups regarding final functional scores and re-tear rates. However, the rotator interval approach group showed a greater increase in ROM at final follow-up, especially in external rotation.

Predictive Factors of Retear in Patients With Repaired Rotator Cuff Tear on Shoulder MRI

This study aimed to find independent prognostic factors related to retear of the rotator cuff tendon in patients with repaired full-thickness supraspinatus tendon tear by evaluation of pre- and postoperative MR images. Shoulder MR images were retrospectively analyzed for 83 patients who had undergone arthroscopic or open rotator cuff repair with acromioplasty for full-thickness supraspinatus tendon tear from April 2014 to March 2015. On preoperative MR images, the type of rotator cuff tear, extent of retraction of torn tendon, anteroposterior (AP) dimension of torn tendon, signal intensity of tear edge, degree of fat infiltration in supraspinatus and infraspinatus muscles, and acromiohumeral interval (AHI) were assessed. Postoperative cuff integrity seen on MR images was classified into five categories according to the Sugaya classification system, and patients were categorized into retear or intact groups. Factors assessed on preoperative MR images were compared between the two groups. The overall retear rate was 57.8%. Significant differences were observed between the retear and intact groups in terms of the mean values of the extent of tendon retraction (20.4 vs 11.7 mm), AP dimension of the tear (16.1 vs 11.4 mm), AHI (6.8 vs 8.7 mm), and degree of fat infiltration of the supraspinatus and infraspinatus muscles (for the supraspinatus muscle, 3, 30, and 15 patients in the retear group vs 5, 27, and three patients in the intact group had Goutallier grade 1, grade 2, and grades 3 and 4 infiltration, respectively; for the infraspinatus muscle, 27, 12, and 9 patients in the retear group vs 29, 5, and one patient in the intact group had Goutallier grade 1, grade 2, and grades 3 and 4 infiltration, respectively). Multivariable analysis revealed that AHI and degree of tendon retraction were independent predictive factors affecting retear of rotator cuff after repair. The retear rate of repaired rotator cuff tendon was about 57.8%. Independent prognostic factors of retear were degree of tendon retraction and AHI on preoperative MR images.

Superior Capsular Reconstruction With Superimposition of Rotator Cuff Repair for Massive Rotator Cuff Tear

Massive rotator cuff tears are particularly challenging to treat and severely limit the function of the shoulder. Compared with a small rotator cuff tear, massive tears are more unpredictable and usually present with low tendon quality. When performing an anatomical repair of the rotator cuff, the surgical treatment is often associated with failure of the construct. An alternative procedure that can be performed in the setting of a massive tear is superior capsular reconstruction (SCR), using an autograft or allograft. This procedure has been shown to be effective and is associated with positive treatment outcomes. Moreover, the combination of an SCR with an anatomic repair of the rotator cuff tendon may provide a stronger fixation for the rotator cuff and ultimately lead to a lower likelihood of retear and failure. The purpose of this Technical Note is to describe our preferred procedure for the treatment of a massive rotator cuff tear through SCR with superimposition of the repair of the native rotator cuff tendons.

What is the role of systemic conditions and options for manipulation of bone formation and bone resorption in rotator cuff tendon healing and repair?

Rotator cuff pathology is a significant cause of shoulder pain. Operative repair of rotator cuff is an established standard of care for these patient, however, failure of the procedure is common. Systemic conditions such as diabetes mellitus, hypocholesteremia, thyroid disease, and smoking significantly affect the outcomes of rotator cuff repair and have significant implications for the management of these patients. Diabetes mellitus has been proposed to damage tendons through non-enzymatic glycosylation of collagen with advanced glycation end product formation and impaired microcirculation. Hypocholesteremia may lead to fatty infiltration and subsequent pro-inflammatory degenerative enzymatic degeneration. Thyroid disease may disrupt tendon homeostasis through the alteration of collagen production and the accumulation of glycosaminoglycans. Lastly, smoking inhibits tendon healing through the induction of hypovascularity and hypoperfusion. Understanding of the implications these systemic conditions have on the outcomes is important in the management of rotator cuff disease.

Targeting Inflammation in Rotator Cuff Tendon Degeneration and Repair.

Rotator cuff degeneration is a common affliction that results in pain and disability. Tendinopathy was historically classified with or without the involvement of the immune system. However, technological advancements in screening have shown that the immune system is both present and active in all forms of tendinopathy. During injury and healing, the coordinated effort of numerous immune cell populations work with the resident stromal cells to break down damaged tissues and stimulate remodeling. These cells deploy a wide array of tools, including phagocytosis, enzyme secretion, and chemotactic gradients to direct these processes. Yet, there remains a knowledge gap in our understanding of the sequence of critical events and regulatory factors that mediate this is process in injury and healing. Furthermore, current treatments do not specifically target inflammation at the molecular level. Typical regimens include non-steroidal anti-inflammatory drugs or corticosteroids; however, researchers have found irrevocable functional deficits following treatment, and have disputed their long-term efficacy. Therefore, developing therapeutics that specifically consider the nuances of the immune system are necessary to improve patient outcomes.

Tendon Repair Leads to better Long-Term Clinical Outcome than Debridement in Massive Rotator Cuff Tears.

Introduction:Massive tears in the rotator cuff are debilitating pathologies normally associated with loss of function and pain. Tendon reconstruction is seen as the standard treatment in order to preserve shoulder function and to inhibit cuff associated osteoarthritis. However, the effect on longer-term shoulder function and patient satisfaction is unknown.Material and Methods:165 consecutive patients with massive tears were included. 57 debridement (mean age 61.9±8.7 years (range 43-77)) and 108 reconstruction (mean age 57.5±8.9 years (range 45-74)) cases could be followed up 2-4 (short-term), 5-6 (mid-term) and 8-10 (long-term) years after surgery. Evaluation was performed with the Constant, a modified ASES and the DASH score. Statistical analysis was done using Sigma-Stat Version 3.5 with a p-value<0.05 indicating statistical significant differences.Results:All three scoring systems showed no significant differences in the short-term follow-up for the two groups (mean values: Constant debridement/repair: 70±11.9/66±13.6; ASES debridement/repair: 22.3±3.3/ 23.3±3.3; DASH debridement/repair: 22.3±11.0/ 24.3±10.1). In the mid-term (Constant debridement/repair: 51±2.9/68.3±5.2; ASES debridement/repair: 20.3±1.3/24.3±1.7; DASH debridement/repair: 31.0±6.5/20.3±5.4) and long-term follow-up (Constant debridement/repair: 42.3±3.8 /60.7±2.6, ASES debridement/repair: 17.3±0.5/21.7±0.5, DASH debridement/repair: 41.3±6.2/25.0±1.4), rotator cuff reconstruction revealed better objective results and better patients’ satisfaction.Conclusion:Rotator cuff tendon repair leads to better long-term clinical outcome and subjective satisfaction compared to debridement. Tendon reconstruction should be considered as a treatment for patients suffering from massive rotator cuff tears, thus preserving shoulder function and by that means delay indication for reverse arthroplasty.

Return to Sports and Work after Arthroscopic Superior Capsule Reconstruction in Patients with Irreparable Rotator Cuff Tears

Objectives:Sports and work can be a causative factor in rotator cuff tears, so that these active patients expect to return to sports and work after surgery. However, in case of irreparable rotator cuff tears, it’s not easy to return to sports and work. A new surgical treatment for irreparable rotator cuff tears, arthroscopic superior capsule reconstruction, restores shoulder stability and muscle balance in patients with irreparable rotator cuff tears; consequently, it improves shoulder function—specifically deltoid muscle function—and relieves pain. In this study, we evaluated the rate of return to sports and work in patients treated with arthroscopic superior capsule reconstruction.Methods:From 2007 to 2014, we performed arthroscopic superior capsule reconstruction on 102 shoulders in 100 patients (mean age 66.7 years; range, 43 to 82) with irreparable rotator cuff tears that had failed conservative treatment. Twenty-six patients played sports before surgery (6 golf, 4 table tennis, 4 swimming, 3 martial arts, 2 baseball, 2 yoga, 1 tennis, 1 badminton, 1 skiing, 1 mountain-climbing, and 1 ground golf). Thirty-four patients had been employed before surgery (21 manual workers, 10 farmers, 1 butcher, 1 cook, and 1 athletic trainer). Also physical examination, radiography, and magnetic resonance imaging were performed before surgery; at 3, 6, and 12 months after surgery; and yearly thereafter. The return-to-sports and work rate and healing rate were analyzed. The American Shoulder and Elbow Surgeons (ASES) score, and active shoulder range of motion were compared between before surgery and at the final follow-up (mean, 48 months; range, 24 to 88 months) by using the t and chi-square tests. A significant difference was defined as P < 0.05.Results:All 26 patients who had played sport before their injuries returned fully to their previous sports, although most of the patients had been playing at recreational level before their injuries. Thirty-two patients returned fully to their previous jobs, whereas two patients (1 farmer and 1 manual worker) returned with reduced hours and workloads. Ninety-five of 102 shoulders (93.1%) had no graft tear or no re-tear of the repaired rotator cuff tendon during the follow-up period. Three shoulders (2.9%) with severe fatty degeneration of the infraspinatus tendon had re-tear of the repaired infraspinatus tendon at 3 months after surgery. Four shoulders (3.9%) suffered a postoperative graft tear by 3 months (2 patients) or 1 year (2 patients) after surgery. The average preoperative American Shoulder and Elbow Surgeons (ASES) score was 31.6 points (range, 3.3 to 63.3 points). Average clinical outcome scores after arthroscopic superior capsule reconstruction all improved significantly at final follow-up (ASES, 93.3 points) (P < .00001). The shoulder active range of motion improved significantly after arthroscopic superior capsule reconstruction at the final follow-up: by 56.9° (92.4° to 149.3°) for elevation (P < .001), by 15.7° (26.0° to 41.6°) for external rotation (P < .01), and by three vertebral bodies (L4 to L1) for internal rotation (P < .01).Conclusion:Arthroscopic superior capsule reconstruction restored shoulder function and resulted in high rates of return to recreational sport and work. These results suggest that arthroscopic superior capsule reconstruction is a viable surgical option for irreparable rotator cuff tears, especially in patients who work and enjoy sport.

Transosseous-equivalent repair with and without medial row suture tying: a cadaveric study of infraspinatus tendon strain measurement

BackgroundHow the use of the transosseous-equivalent (TOE) technique effects the stress concentration in repaired rotator cuff tendon is unknown. This study was conducted to determine the strain between the intact rotator cuff tendon and the tendon repaired using the TOE technique with and without medial row suture tying.Materials and methodsStrain of the infraspinatus tendon from 10 fresh-frozen cadavers was measured at the (A) tendon insertion, (B) tendon footprint, (C) tendon of the medial suture level, and (D) musculotendinous junction of the tendon. The strain was measured during 2 cycles of internal and external rotations while applying 4 different loads to the infraspinatus. After the intact tendon was evaluated, an artificially created tear of the infraspinatus was repaired using the TOE technique. Medial row sutures were tied in 5 shoulders (T group) and untied in the rest (UT group). The strains at 4 sites were compared between the intact and the TOE-repaired tendon and between the T and UT groups.ResultsThe strain was significantly reduced at site B in the repaired tendon in the T and UT groups compared with the intact tendon for all loads (P < .05). At site C, the strain increased for all loads in the T group compared with the intact tendon (P < .05).ConclusionThe strain of the tendon over the footprint area was significantly smaller than the intact tendon when repaired with the TOE technique. The strain at the medial suture level was significantly greater when the medial sutures were tied compared with those untied.

Tight medial knot tying may increase retearing risk after transosseous equivalent repair of rotator cuff tendon.

Retearing mechanism after transosseous equivalent (TOE) rotator cuff repair has not been fully clarified yet. The purposes of this study were to compare the stress distribution pattern in the tendon stump between knotted and knotless TOE repair and to investigate the role of suture tension applied during medial knot tying using a 3-dimensional finite element (3D-FE) method. Both knotted and knotless TOE repairs were simulated on the 3D-FE human rotator cuff tear model. Elastic analysis was performed to compare the stress distribution pattern inside the tendon between the two models. The amount of compressive load applied to the medial-row sutures was then changed as 0, 20, 40, 60, 80, and 100 N in the knotted model. Knotted model demonstrated more distinct stress concentration inside the tendon around medial-row sutures than the knotless model. Mean von Mises equivalent stress in this area in the 0, 20, 40, 60, 80, and 100 N models was 0.26, 0.35, 0.50, 0.70, 1.11, and 1.14 MPa, respectively. In the knotted TOE repair, tight medial knot tying might cause a high stress concentration around medial knots, which may constitute one of the pathogenetic factors of postoperative retearing at this site.

Load response and gap formation in a single‐row cruciate suture rotator cuff repair

Double-row rotator cuff tendon repair techniques may provide superior contact area and strength compared with single-row repairs, but are associated with higher material expenses and prolonged operating time. The purpose of this study was to evaluate gap formation, ultimate tensile strength and stiffness of a single-row cruciate suture rotator cuff repair construct, and to compare these results with those of the Mason-Allen and SutureBridge repair constructs. Infraspinatus tendons from 24 spring lamb shoulders were harvested and allocated to cruciate suture, Mason-Allen and SutureBridge repair groups. Specimens were loaded cyclically between 10 and 62 N for 200 cycles, and gap formation simultaneously measured using a high-speed digital camera. Specimens were then loaded in uniaxial tension to failure, and construct stiffness and repair strength were evaluated. Gap formation in the cruciate suture repair was significantly lower than that of the Mason-Allen repair (mean difference = 0.6 mm, P = 0.009) and no different from that of the SutureBridge repair (P > 0.05). Both the cruciate suture repair (mean difference = 15.7 N/mm, P = 0.002) and SutureBridge repair (mean difference = 15.8 N/mm, P = 0.034) were significantly stiffer than that of the Mason-Allen repair; however, no significant differences in ultimate tensile strength between repair groups were discerned (P > 0.05). The cruciate suture repair construct, which may represent a simple and cost-effective alternative to double-row and double-row equivalent rotator cuff repairs, has comparable biomechanical strength and integrity with that of the SutureBridge repair, and may result in improved construct longevity and tendon healing compared with the Mason-Allen repair.

Biologic and Synthetic Grafts in the Reconstruction of Large to Massive Rotator Cuff Tears.

Rotator cuff injuries are common in both young and elderly patients. Despite improvements in instrumentation and surgical techniques, the failure rates following tendon reconstruction remain unacceptably high. To improve outcomes, graft patches have been developed to provide mechanical strength and to furnish a scaffold for biologic growth across the delicate tendon-bone junction. Although no patch effectively re-creates the structured, highly organized system of prenatal tendon development, augmenting rotator cuff repair may help restore native tendon-to-bone attachment while reproducing the mechanical and biologic properties of native tendon. An understanding of biologically and synthetically derived grafts, along with knowledge of the preliminary data available regarding their combined use with growth factors and stem cells, is needed to improve management and treatment outcomes. The current literature has not been consistent in showing patch augmentation to be beneficial over traditional repair, but novel scaffolding materials may help facilitate rotator cuff tendon repair that is histologically and biomechanically comparable to native tendon.

Involvement of Indian hedgehog signaling in mesenchymal stem cell–augmented rotator cuff tendon repair in an athymic rat model

Bone marrow aspirate has been used in recent years to augment tendon-to-bone healing, including in rotator cuff repair. However, the healing mechanism in cell-based therapy has not been elucidated in detail. Sixteen athymic nude rats were randomly allocated to 2 groups: experimental (human mesenchymal stem cells in fibrin glue carrier) and control (fibrin glue only). Animals were sacrificed at 2 and 4 weeks. Immunohistochemical staining was performed to evaluate Indian hedgehog (Ihh) signaling and SOX9 signaling in the healing enthesis. Macrophages were identified using CD68 and CD163 staining, and proliferating cells were identified using proliferating cell nuclear antigen staining. More organized and stronger staining for collagen II and a higher abundance of SOX9+ cells were observed at the enthesis in the experimental group at 2 weeks. There was significantly higher Gli1 and Patched1 expression in the experimental group at the enthesis at 2 weeks and higher numbers of Ihh+ cells in the enthesis of the experimental group vs control at both 2 weeks and 4 weeks postoperatively. There were more CD68+ cells localized to the tendon midsubstance at 2 weeks compared with 4 weeks, and there was a higher level of CD163 staining in the tendon midsubstance in the experimental group than in the control group at 4 weeks. Stem cell application had a positive effect on fibrocartilage formation at the healing rotator cuff repair site. Both SOX9 and Ihh signaling appear to play an important role in the healing process.

Surgical treatment of anterosuperior impingement of the shoulder

Therapy of intraarticular lesions and elimination of structural risk factors for those suffering from clinical manifest anterosuperiorer impingement (ASI) of the shoulder. This includes as a maximum version the arthroscopic repair of supraspinatus (SST) and subscapularis tendon (SCT) tears with subsequent subpectoral tenodesis of the long head of the biceps tendon (LBT) and arthroscopic coracoplasty. Clinical manifest anterosuperiorer impingement of the shoulder with anterior shoulder pain, failed conservative treatment and clear intraarticular damage in radiological imaging. This involves in detail lesions of the SST, SCT and damage to the LBT. Lack of structural intraarticular lesions or massive osteoarthritis. Persistent dysfunction of active and passive glenohumeral and scapulathoracal motion, due to neurologic deficits or stiff shoulder. A hypertrophic or deformed healed coracoid process is seen as a structural risk factor for suffering from ASI and should be addressed surgically when causing impingement. Arthroscopic tenotomy of the LBT with subsequent repair of the SST and SCT. Arthroscopic coracoplasty if indicated and subpectoral tenodesis of the long head of the biceps. No biceps activity and intermittent immobilization in sling for 6weeks. Limitation of abduction, flexion and external rotation for 6weeks depending on rotator cuff tendon repair. Start of sport-specific training after 3months, over-head sports 6months postoperatively. The arthroscopic repair of anterosuperior rotator cuff tears provides reliable results for improvement in function, decreases in pain and improvement in shoulder scores. The overall rate of adverse events is low.

Postoperative pain after arthroscopic versus open rotator cuff repair. A prospective study

IntroductionAlthough the arthroscopic technique is becoming the gold standard for rotator cuff tendon repair, there is no proof that this technique results in less postoperative pain compared to open repair. The aim of this study was to prospectively compare the postoperative pain level after arthroscopic or open rotator cuff repair and to define factors that could influence its course. Materials and methodsBetween January 2012 and January 2013, 95 patients were operated for a rotator cuff tear: 45 using an arthroscopic technique and 50 an open technique. Daily analgesic use and self-evaluation of pain level using a visual analogic scale were recorded preoperatively and twice a day postoperatively during the first 6 weeks. These data were compared between the two groups and analyzed according to patients’ demographic data and preoperative evaluation of the tear. ResultsThe preoperative pain level was equivalent in the two groups (P=0.22). Postoperatively, level-2 analgesic medication use was greater in the arthroscopic group after the 4th week (P=0.01). A pain-free shoulder was obtained before the 6th week in 75% and 66% of the patients after arthroscopic or open repair, respectively (P=0.34). There was a positive correlation between the preoperative and postoperative pain level (r=0.25; P=0.02). Work compensation patients experienced more pain postoperatively (P=0.08). Level-III analgesic medication use was greater for patients with massive rotator cuff tear (P=0.001). ConclusionNo evidence was found on the superiority of arthroscopy versus open repair of rotator cuff tear concerning the postoperative pain level. The choice of the surgical technique should not be based on this argument. Level of evidenceII.

The Optimum Tension for Bridging Sutures in Transosseous-Equivalent Rotator Cuff Repair

Background: Transosseous-equivalent (TOE) rotator cuff repair can increase contact area and contact pressure between the repaired cuff tendon and bony footprint and can show higher ultimate loads to failure and smaller gap formation compared with other repair techniques. However, it has been suggested that medial rotator cuff failure after TOE repair may result from increased bridging suture tension. Purpose: To determine optimum bridging suture tension in TOE repair by evaluating footprint contact and construct failure characteristics at different tensions. Study Design: Controlled laboratory study. Methods: A total of 18 fresh-frozen cadaveric shoulders, randomly divided into 3 groups, were constructed with a TOE configuration using the same medial suture anchor and placing a Tekscan sensing pad between the repaired rotator cuff tendon and footprint. Nine of the 18 shoulders were used to measure footprint contact characteristics. With use of the Tekscan measurement system, the contact pressure and area between the rotator cuff tendon and greater tuberosity were quantified for bridging suture tensions of 60, 90, and 120 N with glenohumeral abduction angles of 0° and 30° and humeral rotation angles of 30° (internal), 0°, and 30° (external). TOE constructs of all 18 shoulders then underwent construct failure testing (cyclic loading and load to failure) to determine the yield load, ultimate load, stiffness, hysteresis, strain, and failure mode at 60 and 120 N of tension. Results: As bridging suture tension increased, contact force, contact pressure, and peak pressure increased significantly at all positions (P < .05 for all). Regarding contact area, no significant differences were found between 90 and 120 N at all positions, although there were significant differences between 60 and 90 N. The construct failure test demonstrated no significant differences in any parameters according to various tensions (P > .05 for all). Conclusion: Increasing bridging suture tension to over 90 N did not improve contact area but did increase contact force and pressure. Bridging suture tension did not significantly affect ultimate failure loads. Clinical Relevance: Considering the risks of overtensioning bridging sutures, it may be clinically more beneficial to keep bridging suture tension below 90 N.

The Effect of Recombinant Human Parathyroid Hormone (rhPTH) on Tendon-to-Bone Healing in a Rat Rotator Cuff Model

Objectives:Successful rotator cuff tendon repair is predicated upon secure tendon-to-bone healing. A recent study has shown that recombinant human parathyroid hormone (rhPTH) treatment results in improved tendon-to-bone healing at the latter stages of healing, but not at early time points. We hypothesized that delaying administration of rhPTH until after the acute inflammatory phase would improve tendon-to-bone healing at all time points in a rat rotator cuff repair model.Methods:One hundred and eight male Sprague Dawley rats underwent detachment and subsequent repair of the supraspinatus tendon based on an a priori power analysis. Fifty four rats underwent repair alone and 54 rats received repair plus daily subcutaneous injections of 10 µg/kg of rhPTH beginning on postoperative day 7 and continuing for 12 weeks. Rats were sacrificed at 2 and 16 weeks postoperatively for biomechanical testing or histologic and immunohistochemical analysis. Histologic slides were digitized, and the enthesis was evaluated quantitatively using NIH Image J and VisioMorph software.Results:At 2 weeks postoperatively, the rhPTH group had significantly higher load to failure than the control group (10.85 versus 5.16 N; p = 0.003). At 16 weeks, there was no significant difference in load to failure between the two groups (Figure 1). With respect to stiffness of the repair, there was no significant difference between the two groups at either time point, but there was a trend toward increased stiffness in the rhPTH group at 2 weeks postoperatively compared to the control group (5.09 vs. 3.77 N/mm; p = 0.12). Histologically, the rhPTH specimens had more fibrocartilage and osteoblasts at all time points, with significantly better collagen fiber orientation at 2 weeks.Conclusion:Administration of rhPTH significantly increased load to failure at 2 weeks postoperatively in a rat rotator cuff repair model, with improved collagen fiber organization and increased fibrocartilage formation. Delaying administration of rhPTH until postoperative day number 7, after the resolution of the acute inflammation from surgery had subsided, improved rotator cuff healing in the early postoperative period while maintaining later-stage mechanical strength.

Longitudinal Supraspinatus Tear Associated with Antegrade Humeral Intramedullary Nailing: A Case Report and Literature Review with Focus Placed on Nail Entry Point

Iatrogenic damage of the rotator cuff followed by postoperative shoulder function loss is a potential complication after antegr- ade intramedullary nailing (AIN) for a humeral fracture. The authors present a case of arthroscopic rotator cuff repair and subacromial decom-pression of a non-healed rotator cuff tendon (mainly supraspinatus) and secondary impingement syndrome caused either by the tear or a proud nail after AIN for a mid-shaft humeral fracture. At presentation, the patient complained of right shoulder pain and ‘snapping’, especially during forward elevation and abduction of the shoulder, of 4 years duration. Right shoulder pain started sometime after pain due to the humeral shaft fracture, operation had subsided, and persisted after nail removal. Arthroscopic findings showed a lon- gitudinal rotator cuff tear at the nail entry point that had not healed and severe fibrous hypertrophy on the acromion underspace, which is a unique finding since most longitudinal splits of tendon fibers are more likely to heal than conventional rotator cuff tears detached from bone. The torn rotator cuff was repaired after debridement and placing side-to-side sutures. At his 34-month follow-up after rotator cuff repair, the patient showed complete recovery and had excellent clinical scores.(Clin Shoulder Elbow 2015;18(1):47-51)Key Words: Rotator cuff; Complications; Intramedullary nailing; Arthroscopy