Nonlinear stress analysis of the supraspinatus tendon using three-dimensional finite element analysis

Purpose

No studies have used stress analysis with finite element analysis (FEA) to determine the causes of and mechanisms underlying rotator cuff tears. Therefore, we performed a biomechanical evaluation of the changes in stress distribution on the rotator cuff using three-dimensional (3-D) FEA.

Methods

The 3-D FEA model of shoulder joint allowed for abduction angles of 0°, 45° and 90° from the plane of the scapula and included the anatomical insertion points of the three major rotator cuff tendons and the middle fibres of the deltoid muscle. Stress distribution of the supraspinatus tendon on 3-D FEA was validated by a comparison with cadaveric and two-dimensional finite element model.

Results

The principal stress peaked in the region approximately 1 cm proximal to the insertion of the supraspinatus tendon. Furthermore, the stress on the joint side increased at the anterior edge of the supraspinatus tendon at abduction angles of 45° and 90°.

Conclusion

There are differences in stress changes between the joint side and bursal side of the supraspinatus tendon within the angles of abduction. The maximal tensile stress was observed on the articular side of the anterior edge of the supraspinatus tendon at 90° abduction. Our results indicate that the difference in tensile stress between the two layers results in delamination and causes partial-thickness tears.

Level of evidence

Decision analysis, Level II.     

The effects of Low-intensity Pulsed Ultrasound on tendon-bone healing in a transosseous-equivalent sheep rotator cuff model

Purpose

The purpose of this study was to examine the effects Low-intensity Pulsed Ultrasound has on initial tendon-bone healing in a clinically relevant extra-articular transosseous-equivalent ovine rotator cuff model.

Methods

Eight skeletally mature wethers, randomly allocated to either control group (n = 4) or treatment group (n = 4), underwent rotator cuff surgery following injury to the infraspinatus tendon. All animals were killed 28 days post surgery to allow examination of early effects of Low-intensity Pulsed Ultrasound treatment.

Results

General improvement in histological appearance of tendon-bone integration was noted in the treatment group. Newly formed woven bone with increased osteoblast activity along the bone surface was evident. A continuum was observed between the tendon and bone in an interdigitated fashion with Sharpey’s fibres noted in the treatment group. Low-intensity Pulsed Ultrasound treatment also increased bone mineral density at the tendon-bone interface (p < 0.01), while immunohistochemistry results revealed an increase in the protein expression patterns of VEGF (p = 0.038), RUNX2 (p = 0.02) and Smad4 (p = 0.05).

Conclusions

The results of this study indicate that Low-intensity Pulsed Ultrasound may aid in the initial phase of tendon-bone healing process in patients who have undergone rotator cuff repair. This treatment may also be beneficial following other types of reconstructive surgeries involving the tendon-bone interface.     

Stitch positioning influences the suture hold in supraspinatus tendon repair

Purpose

This study was designed to compare the pull-out strength of simple suture stitches in human supraspinatus tendons with respect to the position of the rotator cable.

Methods

Fifty-four tests were performed on 6 intact, human supraspinatus tendons, to assess the cutout strength of a simple suture configuration in different positions; medial to, lateral to, or within the rotator cable. Tendon thickness was measured and correlated for each positioned suture.

Results

Suture positioning lateral to or in the rotator cable showed significantly lower suture retention properties compared with positioning the suture medial to the cable (p = 0.002). In all tested specimens, the central stitch in the row medial to the rotator cable provided the optimum retention properties (mean: 191 N; SD: ± 44; p < 0.01), even after correcting for tendon thickness.

Conclusion

This study shows that it is desirable to identify the rotator cable and to pass sutures just medial to it, close to the middle of the tendon, which provided highest possible suture retention properties.     

Expression levels of matrix metalloproteinase (MMP)-9 and its specific inhibitor TIMP-1, in septic and aseptic arthritis of the knee

Purpose

In cases of septic knee arthritis, there is excess of matrix metalloproteinases (MMPs) over tissue inhibitors of metalloproteinases (TIMPs), due to enhanced expression and activation that are induced by bacteria in comparison with rheumatic or degenerative arthritis. The aim of this study was to explore the expression levels of synovial gelatinase MMP-9 and its specific inhibitor TIMP-1 in septic and aseptic arthritis and their potential use as additional aids to clinical investigation.

Methods

Gelatin zymography and western blot analysis were applied in effusions from knees of the patients with septic (SA—10 patients), rheumatic (RA—10 patients) and osteoarthritis (OA—10 patients).

Results

Zymographic analysis revealed that all samples contained latent MMP-2 activity, albeit activated MMP-2 appeared in more of the septic than aseptic effusions. MMP-9 was not detected in osteoarthritic synovial fluid samples. Only trace amounts of MMP-9 activity were detected in 4 of 10 patients with RA, whereas higher MMP-9 levels were evident in all samples from SA (P = 0.0241). In immunoblotting assays, samples from SA showed significantly higher levels of MMP-9 compared with samples from RA (P = 0.0052), confirming zymographic results. Although no significant difference in TIMP-1 levels was observed, the estimated MMP-9/TIMP-1 ratio of septic effusions was significantly higher compared with aseptic ones (P = 0.0029).

Conclusions

The data presented suggest enhanced expression and activation of MMP-9 in septic native knee arthritis compared with aseptic. The presence of high levels of MMP-9 with concomitantly increased MMP-9/TIMP-1 ratio and activated gelatinases in effusions, independent of neutrophilic counts, may be indicative for infection.     

Degree of tendon degeneration and stage of rotator cuff disease

Purpose

While tendon degeneration has been known to be an important cause of rotator cuff disease, few studies have objectively proven the association of tendon degeneration and rotator cuff disease. The purpose of this study was to investigate changes of tendon degeneration with respect to the stage of rotator cuff disease.

Methods

A total of 48 patients were included in the study: 12 with tendinopathy, 12 with a partial-thickness tear (pRCT), 12 with a full-thickness tear (fRCT), and 12 as the control. A full-thickness supraspinatus tendon sample was harvested en bloc from the middle portion between the lateral edge and the musculotendinous junction of the tendon using a biopsy punch with a diameter of 3 mm. Harvested samples were evaluated using a semi-quantitative grading scale with 7 parameters after haematoxylin and eosin staining.

Results

There was no significant difference in age, gender, symptom duration, and Kellgren-Lawrence grade between the groups except for the global fatty degeneration index. All of the seven parameters were significantly different between the groups and could be categorized as follows: early responders (fibre structure and arrangement), gradual responder (rounding of the nuclei), after-tear responders (cellularity, vascularity, and stainability), and late responder (hyalinization). The total degeneration scores were not significantly different between the control (6.08 ± 1.16) and tendinopathy (6.67 ± 1.83) (n.s.). However, the score of pRCT group (10.42 ± 1.31) was greater than that of tendinopathy (P < 0.001), and so was the score of fRCT (12.33 ± 1.15) than that of pRCT (p = 0.009).

Conclusion

This study showed that the degeneration of supraspinatus tendon increases as the stage of rotator cuff disease progresses from tendinopathy to pRCT, and then to fRCT. The degree of degeneration of tendinopathy was not different from that of normal but aged tendons, and significant tendon degeneration began from the stage of pRCT. The clinical relevance of the study is that strategies and goals of the treatment for rotator cuff disease should be specific to its stage, in order to prevent disease progression for tendinopathy and pRCT, as well to restore the structural integrity for fRCT.

Level of evidence

Diagnostic, Level I.

     

Clinical outcomes after arthroscopic trans-tendon suture-bridge technique in partial-thickness articular-side rotator cuff tear

Purpose

We evaluated the functional and radiological outcomes of arthroscopic trans-tendon suture-bridge repair for partial-thickness articular-side rotator cuff tears.

Methods

From December 2008 to May 2010, 32 consecutive patients with partial-thickness articular-side rotator cuff tears prospectively underwent arthroscopic trans-tendon suture-bridge repair. We included patients with articular-side partial-thickness supraspinatus tears involving more than half the normal thickness. Patients underwent ultrasonography or magnetic resonance imaging postoperatively. The functional outcomes of patients were evaluated at a minimum 1 year postoperatively. The mean age and follow-up period for the patients were 51.8 ± 13.7 years and 17.4 ± 4.2 months, respectively. Five outcome measures were used before surgery and at the final follow-up: a visual analog scale (VAS) pain score, the American Shoulder and Elbow Surgeons (ASES) score, the Shoulder Rating Scale of the University of California at Los Angeles (UCLA), the Constant–Murley score and range of motion (ROM).

Results

The radiological follow-up rate was 87.5 %, and the follow-up rate for clinical evaluation was 96.9 %. Mean UCLA, ASES and Constant–Murley scores improved from 19.1 ± 5.4, 45.2 ± 16.0 and 58.0 ± 19.6 preoperatively to 35.7 ± 8.5, 79.0 ± 15.8 and 78.1 ± 12.9 at final follow-up, respectively (all p ≤ 0.001). Mean VAS score and ROM (forward flexion) improved from 6.1 ± 1.9 and 140 ± 36.6 preoperatively to 2.6 ± 1.9 and 163 ± 25.2 at the final follow-up, respectively (p ≤ 0.001). Additionally, the postoperative radiological examination showed cuff integrity without retear in all patients.

Conclusions

Arthroscopic trans-tendon suture-bridge repair for partial-thickness articular-side rotator cuff tears resulted in significant improvement in function compared with that before the operation.     

Superiority of bridging techniques with medial fixation on initial strength

Purpose

The purpose of our study was to evaluate the initial fixation strength of bridging techniques compared to other suture techniques for rotator cuff repair using a biomechanical animal model, which incorporated pretesting of intact tendons.

Methods

Seventy-six fresh bovine shoulders were used for testing seven suture configurations including simple suture (SS), mattress suture (MS), Mason-Allen (MA), modified double row (mDR), SpeedBridge (SpB), SpeedBridge with medial fixation (mSpB), and double-mattress SutureBridge (dmSuB) techniques. Cyclic loading was performed with all intact bone-tendon complex before (pretest) and after repair of the tendon (main test) at the level of 10 and 180 N at 100 Hz with displacement-controlled ramps of ±33 mm/s. The pretest was stopped after 200 cycles. For the main test, the loading scheme was continued for a maximum of 500 cycles or until failure.

Results

The mean elongation of all 76 intact tendons measured at the pretest was 3.8 ± 0.6 mm (2.4–5.4 mm). No differences of gap formations at the 1st cycle were detected between SS, MS, MA, and mDR. SpB showed significant higher gap formations compared to all other suture techniques (p = 0.001). No significant differences were detected between mSpB and dmSuB, whereas both techniques were significant different when compared to the other groups (p < 0.05).

Conclusions

In this study, results showed that bridging techniques with medial fixations have superior initial repair strength compared to other suture techniques. Knowledge of initial fixation strength of rotator cuff repair techniques may be of informative value to the surgeon.     

Extracorporeal shock wave therapy is not useful after arthroscopic rotator cuff repair

Purpose

Extracorporeal shock wave therapy (ESWT) is known to accelerate the healing of musculoskeletal tissue. The purpose of this study was to test the hypothesis that ESWT stimulates rotator cuff healing after arthroscopic repair.

Methods

Seventy-one consecutive patients with a small- to large-sized rotator cuff tear underwent arthroscopic rotator cuff repair. The patients were randomized into two groups: 35 patients underwent ESWT at 6 weeks after surgery (ESWT group) and 36 patients did not (control group). Cuff integrity was evaluated with computed tomographic arthrography at 6 months after surgery. Constant and UCLA scores were measurable outcomes.

Results

All patients were available for a minimum one-year follow-up. The mean age of the ESWT and control groups was 59.4 (SD: 7.7) and 58.6 years (SD: 7.8) (n.s.). There were no significant differences in tear size and repair method between the two groups (n.s.). The mean Constant and UCLA scores, respectively, increased from 54.6 to 90.6 (P < 0.001) and from 18.5 to 27.4 (P < 0.001) in the ESWT group, and from 58.9 to 89.3 (P < 0.001) and 18.5 to 27.4 in the control group. Computed tomographic arthrography was performed in 26 patients from the ESWT group and 24 from the control group, and cuff integrity was maintained in 46 out of 50 patients. Definite re-tear was observed in two patients of the ESWT group and four of the controls. There were no complications associated with ESWT.

Conclusion

This study failed to prove that ESWT stimulates rotator cuff healing after arthroscopic rotator cuff repair. Additional ESWT after rotator cuff repair could theoretically be advantageous, and it was proven to be safe in this study.

Level of evidence

II.     

Palpation tests versus impingement tests in Neer stage I and II subacromial impingement syndrome

Purpose

Using sonographic findings to test the diagnostic accuracy of impingement versus tendon palpation tests in Neer stage I and II subacromial impingement syndrome cases and examine their clinical potential.

Methods

Neer and Hawkins impingement tests and rotator cuff tendon palpation tests followed by bilateral shoulder sonography were conducted on 69 patients with a clinical diagnosis of unilateral subacromial impingement.

Results

The Neer and Hawkins tests had 74 and 62 % accuracy (sensitivity 80 and 67 %, and specificity 52 and 47 %, respectively) in comparison to 79 and 62 % accuracy rates for supraspinatus and biceps tendon palpation tests (sensitivity 92 and 41 %, and specificity 41 and 48 %, respectively). Overall, the palpation tests scored better than impingement tests in the diagnosis of Neer stage I and II subacromial impingement syndrome. No tendinosis or tear was noted in patients with negative findings in the supraspinatus palpation tests (sensitivity 100 %, specificity 21 %).

Conclusion

Palpation tests for supraspinatus and biceps tendons have a slightly higher accuracy than the impingement tests, and if tenderness does not exist then supraspinatus tendinopathy can be ruled out. These findings warrant the use of palpation tests in a routine physical examination for tendinopathy.

Level of evidence

I.     

Increased levels of apoptosis and p53 in partial-thickness supraspinatus tendon tears

Purpose

The role of apoptosis in the progression of rotator cuff tendinopathy remains poorly understood. In particular, the extent of apoptosis in the partially torn supraspinatus tendon has not been well examined.

Methods

Biopsies were obtained from nine partially torn supraspinatus tendons, from the matched intact subscapularis tendons, and from 10 reference subscapularis tendons. Immunohistochemistry was used to assess the density of apoptotic cells (activated caspase-3; Asp175), proliferation (Ki67), and p53 (M7001), a key protein involved in regulating cell death. The Bonar scale was used to evaluate tendon degeneration.

Results

The density of apoptotic tendon cells and the density of cells expressing p53 were significantly increased in both the partially torn supraspinatus tendons and in the matched subscapularis tendons, compared with uninjured reference tendons. The Bonar score revealed significant tendon degeneration in the partially torn supraspinatus tendons compared with both matched and reference subscapularis tendons. Tendon cell proliferation was significantly increased in the partially torn supraspinatus tendons compared with reference subscapularis tendons.

Conclusions

Partial-thickness tears of the supraspinatus tendon demonstrated an increased density of apoptotic, p53+ tendon cells. The fact that apoptosis was accompanied by increased tendon cell proliferation suggests that apoptosis may be related to an ongoing injury-repair process. Increased tenocyte apoptosis may be a relatively early feature in rotator cuff tendinopathy and could represent a possible target for therapeutic intervention.     

Regeneration of hamstring tendons after anterior cruciate ligament reconstruction

Purpose

Primary aim of the study was analysis of hamstring tendon regeneration after anterior cruciate ligament reconstruction (ACLR). Secondary aim was analysis of isokinetic muscle strength in relation to hamstring regeneration. The hypothesis was that regeneration of hamstring tendons after ACLR occurs and that regenerated hamstring tendons contribute to isokinetic hamstring strength with regeneration distal to the knee joint line.

Methods

Twenty-two patients scheduled for ACLR underwent prospective MRI analysis of both legs. MRI parameters were tendon regeneration and morphology, muscle retraction and muscle cross-sectional area. A double-blind, prospective analysis of isokinetic quadriceps and hamstrings strength was performed.

Results

Regeneration of the gracilis tendon after ACLR occurred in all patients. Regeneration of the semitendinosus tendon occurred in 14 patients. At 1 year, the surface area of the semitendinosus and gracilis muscle decreased compared to both preoperatively (P < 0.01) and the contralateral leg (P < 0.01). The cross-sectional area of the semitendinosus muscle decreased in the absence of tendon regeneration (P = 0.05). The cross-sectional area of the gracilis muscle was greater in case of regeneration distal to the joint line (P = 0.01). Muscle retraction of the semitendinosus muscle was increased in case of nonregeneration (P = 0.02). There was no significant relationship between isokinetic flexion strength and tendon regeneration.

Conclusion

Hamstring tendons regenerated after harvest of both semitendinosus and gracilis tendons for ACLR. There was no relation between isokinetic flexion strength and tendon regeneration.

Level of evidence

Prognostic study, Level II.     

Repaired Supraspinatus Tendons in Clinically Improving Patients: Early Postoperative Findings and Interval Changes on MRI

Objective

To demonstrate and further determine the incidences of repaired supraspinatus tendons on early postoperative magnetic resonance imaging (MRI) findings in clinically improving patients and to evaluate interval changes on follow-up MRIs.

Materials and Methods

Fifty patients, who showed symptomatic and functional improvements after supraspinatus tendon repair surgery and who underwent postoperative MRI twice with a time interval, were included. The first and the second postoperative MRIs were obtained a mean of 4.4 and 11.5 months after surgery, respectively. The signal intensity (SI) patterns of the repaired tendon on T2-weighted images from the first MRI were classified into three types of heterogeneous high SI with fluid-like bright high foci (type I), heterogeneous high SI without fluid-like bright high foci (type II), and heterogeneous or homogeneous low SI (type III). Interval changes in the SI pattern, tendon thickness, and rotator cuff interval thickness between the two postoperative MRIs were evaluated.

Results

The SI patterns on the first MRI were type I or II in 45 tendons (90%) and type III in five (10%). SI decreased significantly on the second MRI (p < 0.050). The mean thickness of repaired tendons and rotator cuff intervals also decreased significantly (p < 0.050).

Conclusion

Repaired supraspinatus tendons exhibited high SI in 90% of clinically improving patients on MRI performed during the early postsurgical period. The increased SI and thickness of the repaired tendon decreased on the later MRI, suggesting a gradual healing process rather than a retear.     

Expression of insulin-like growth factor type 1 receptor and myosin heavy chain in rabbit’s rotator cuff muscle after injection of adipose-derived stem cell

Purpose

This study was performed to evaluate the effects of adipose-derived mesenchymal stem cells (ADMSC) in a subacute rotator cuff tear model of a rabbit by way of comparing the expression of insulin-like growth factor 1 receptor (IGF-1R) and myosin heavy chain (MyHC) in the ADMSC injected muscle and control.

Methods

Supraspinatus tears were created in both shoulders of 11 rabbits, and rotator cuff repair was performed after 3 weeks. At the time of repair, each side of the shoulders was randomly selected, and the injection of the ADMSCs at the muscle belly near musculotendinous junction (injection side) and saline to the contralateral side (control side) was performed. After 3 weeks, we randomly assigned 5 rabbits to the immunohistochemistric analysis and 6 to Western blot analysis.

Results

Expression of both IGF-1R (95 kD) and MyHC (200 kD) at the injection side was significantly elevated compared to control side (both p = 0.028). Immunohistochemistry showed that staining areas of both IGF-1R and MyHC were overlapped with staining of ADMSCs.

Conclusion

The injection of ADMSCs resulted in high expression of IGF-1R and MyHC in subacute rotator cuff tear and repaired model in rabbit compared to control side. Therefore, the injected ADMSCs may assist in regeneration of the rotator cuff muscle by way of insulin-like growth factor 1 (IGF-1) signalling pathway. This result may suggest another solution to facilitate the recovery of rotator cuff muscle and to improve the result of rotator cuff repair by ADMSC injection via IGF-1 pathway, which is one of the potent anabolic pathways.     

Adhesion and collagen production of human tenocytes seeded on degradable poly(urethane urea)

Purpose

The aim of this study was to investigate whether human tenocytes taken from ruptured quadriceps tendon could be seeded on a biodegradable polycaprolactone-based polyurethanes (PU) urea scaffold. Scaffold colonization and collagen production after different culture periods were analyzed to understand whether tenocytes from ruptured tendons are able to colonize these biodegradable scaffolds.

Methods

Human primary tenocyte cultures of ruptured quadriceps tendons were seeded on PU scaffolds. After 3, 10 and 15 days of incubation, the samples were stained with haematoxylin and eosin and were examined under white light microscopy. After 15 and 30 days of incubation, samples were examined under transmission electron microscope. Total collagen accumulation was also evaluated after 15, 30 and 45 days of culture.

Results

After 15 and 30 days of culture, tenocyte-seeded scaffolds showed cell colonization and cell accumulation around interconnecting micropores. Tenocyte phenotype was variable. Collagen accumulation in seeded scaffolds demonstrated a progressive increase after 15, 30 and 45 days of culture, while control non-seeded scaffolds show no collagen accumulation.

Conclusion

These results showed that human tenocytes from ruptured quadriceps tendon can be seeded on polycaprolactone-based PU urea scaffolds and cultured for a long time period (45 days). This study also showed that human tenocytes from ruptured tendons seeded on PU scaffolds are able to penetrate the scaffold showing a progressively higher collagen accumulation after 15, 30 and 45 days of incubation. This study provides the basis to use this PU biodegradable scaffold in vivo as an augmentation for chronic tendon ruptures and in vitro as a scaffold for tissue engineering construct.     

Randomized, controlled trial of multimodal shoulder injection or intravenous patient-controlled analgesia after arthroscopic rotator cuff repair

Purpose

The aim of this study was to compare the effect of postoperative pain control and adverse effects of intravenous patient-controlled analgesia (IV PCA) and multimodal shoulder injection after arthroscopic rotator cuff repair.

Methods

Seventy patients scheduled for elective arthroscopic rotator cuff repair were prospectively randomized to receive either IV PCA or multimodal shoulder injections. Postoperative pain, nausea, vomiting, and other adverse effects were assessed at 2, 6, 12, 24, and 48 h after surgery. Use of rescue analgesics and antiemetics, level of satisfaction, and cost for both modalities were recorded.

Results

Pain was better controlled in the multimodal shoulder injection group at 2 h postoperatively (P = 0.001). However, the use of additional analgesics was greater in the multimodal shoulder injection group during 12–48 h after surgery (P < 0.001). The incidence of nausea within 12–24 h after surgery in the multimodal shoulder injection group (5.7 %) was less significant compared with that in the IV PCA group (31.4 %, P = 0.012), but no difference in overall incidence of the use of rescue antiemetics was observed between the groups (n.s.). No differences in adverse effects were noted between the groups. Patient satisfaction also showed no differences (n.s.). Costs required for both modalities were $20.3 for the multimodal shoulder injection and $157.8 for the IV PCA.

Conclusions

Multimodal shoulder injection is a safe and effective modality for management of pain after arthroscopic rotator cuff repair. Considering the expense and need of special devices for IV PCA, multimodal shoulder injection may be an effective and safe alternative to IV PCA for postoperative analgesia after arthroscopic rotator cuff repair.

Level of evidence

Randomized, controlled trial, Level I.     

Does adding heavy load eccentric training to rehabilitation of patients with unilateral subacromial impingement result in better outcome? A randomized, clinical trial

Purpose

To investigate superior value of adding heavy load eccentric training to conservative treatment in patients with subacromial impingement.

Methods

Sixty-one patients with subacromial impingement were included and randomly allocated to the traditional rotator cuff training (TT) group (n = 30, mean age = 39.4 ± 13.1 years) or traditional rotator training combined with heavy load eccentric training (TT + ET) group (n = 31, mean age = 40.2 ± 12.9 years). Isometric strength was measured to abduction at 0°, 45° and 90° of scapular abduction and to internal and external rotation. The SPADI questionnaire was used to measure shoulder pain and function. Patients rated subjective perception of improvement. Outcome was assessed at baseline, at 6 and 12 weeks after start of the intervention. Both groups received 9 physiotherapy treatments over 12 weeks. At home, the TT group performed traditional rotator cuff strengthening exercises 1x/day. The TT + ET group performed the same exercises 1x/day and a heavy load eccentric exercise 2x/day.

Results

After treatment, isometric strength had significantly increased in all directions, and SPADI score had significantly decreased. The TT + ET group showed a 15 % higher gain in abduction strength at 90° of scapular abduction. Chi-square tests showed patients’ self-rated perception of improvement was similar in both groups.

Conclusion

Adding heavy load eccentric training resulted in a higher gain in isometric strength at 90° of scapular abduction, but was not superior for decreasing pain and improving shoulder function. This study showed that the combination of a limited amount of physiotherapy sessions combined with a daily home exercise programme is highly effective in patients with impingement.

Level of evidence

II.     

Platelet-rich plasma in tendon-related disorders: results and indications

Purpose

Platelet-rich plasma (PRP) is currently the most exploited strategy in the clinical practice to provide a regenerative stimulus for tendon healing. The aim of the present study was to systematically review the available evidence on the treatment of the main tendon disorders where PRP is currently applied.

Methods

A systematic review of the literature was performed on the use of PRP as a treatment for tendinopathies focusing on the following sites: Achilles tendon, patellar tendon, rotator cuff tendons, and lateral elbow tendons. The following inclusion criteria for relevant articles were used: clinical trials written in English language up to 21 June 2016 on the use of PRP in the conservative or surgical treatment of the aforementioned tendinopathies.

Results

The research identified the following clinical trials dealing with the application of PRP in the selected tendons: 19 papers on patellar tendon (6 being RCTs: 4 dealing with PRP conservative application and 2 surgical), 24 papers on Achilles tendon (4 RCTs: 3 conservative and 1 surgical), 29 on lateral elbow tendons (17 RCTs, all conservative), and 32 on rotator cuff (22 RCTs: 18 surgical and 3 conservative).

Conclusion

Patellar tendons seem to benefit from PRP injections, whereas in the Achilles tendon, PRP application is not indicated neither as a conservative approach nor as a surgical augmentation. Lateral elbow tendinopathy showed an improvement in most of the high-level studies, but the lack of proven superiority with respect to the more simple whole-blood injections still questions its use in the clinical practice. With regard to rotator cuff pathology, the vast majority of surgical RCTs documented a lack of beneficial effects, whereas there is still inconclusive evidence concerning its conservative application in rotator cuff disorders.

Level of evidence

Systematic review of level I–IV trials, Level IV.

     

Rotator cable at MR imaging: considerations on morphological aspects and biomechanical role

Purpose

The rotator cable (RC) is a thickening of the coracohumeral ligament. It extends from the coracohumeral ligament to the inferior border of the infraspinatus tendon, with fibres running perpendicularly to the rotator cuff fibres. According to some authors, the RC tends to thicken with age, thus allowing some individuals with a cuff lesion to preserve normal shoulder function. We evaluated the RC with magnetic resonance (MR) imaging and investigated its possible role in the biomechanics of the shoulder affected by cuff lesions.

Materials and methods

Between November 2007 and May 2008, we performed shoulder MR examinations for shoulder pain or disability on 94 patients (46 males, 48 females; age range 16?C79 years; mean age 54.09±15.09 years) for a total of 104 shoulders (62 right, 42 left).

Results

RC was more easily detectable in oblique coronal scans where it appeared as a crescent-shaped, regularly marginated structure adjacent to the articular surface of the supraspinatus tendon and medial to the insertion point of this tendon on the greater tuberosity. Its thickness was 2.8±0.3 mm. The structure was identified in 62% of cases (mean patient age 55.3±14.9 years). No statistically significant difference in age was found between patients with and without evidence of RC (Student??s t test=0.05; p=0.82). Among patients with partial- or full-thickness supraspinatus tendon lesions at MR imaging, no statistically significant difference was found between the presence or absence of RC and disability on Jobe??s test (??²=1.17; p>0.05).

Conclusions

RC can be observed at MR imaging in >60% cases. In our sample it did not seem to influence shoulder function in patients with cuff lesions.     

Anti-inflammatory cytokine profile in early human tendon repair

Purpose

The aim of this study was to assess inflammation and the presence and relative levels of cytokines, which may be involved in regulating early human Achilles tendon healing.

Methods

Nine patients with acute Achilles tendon rupture were included, operated on and post-operatively immobilized. Two weeks post-operatively, microdialysis of the peritendinous interstitial compartment was performed in the healing and intact contralateral Achilles tendons. Quantification of tumour necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12p70 and IL-17A was accomplished using a cytometric bead array. Prostaglandin (PG) E₂ levels were measured by enzyme immunoassay.

Results

None of the patients displayed detectable PGE₂ levels. Pro-inflammatory cytokines were below detection levels (IFNγ, IL-12, and IL-17) or did not differ between injured and control tendons (IL-1β and TNF). Notably, IL-6, IL-8 and IL-10 concentrations in the healing Achilles tendon were significantly elevated: 13-fold (p = 0.009), 28-fold (p = 0.02), and 3.7-fold (p = 0.03), respectively.

Conclusion

At 2 weeks post–human Achilles tendon rupture, healing is characterized by a resolving inflammatory phase and up-regulation of IL-6, IL-8 and IL-10. The absence of inflammation suggests that at this time point, these cytokines may be associated with anti-inflammatory and regenerative effects on the tendon healing process.