Progress in Biomechanical Study of Rotator Cuff Repair / 医用生物力学

The rotator cuff is an important structure to maintain movement and dynamic stability of the shoulder joint. Rotator cuff injury changes its unique biomechanical effects, resulting in shoulder pain and mobility disorders. Although great progress has been made in suture technology and fixation method, the rate of postoperative retear is still very high. Understanding the biomechanical mechanism of normal rotator cuff and restoring the special biomechanical effect of rotator cuff after injury are the key to prevent postoperative retear. This article reviewed biomechanical researches on rotator cuff repair in recent years, in order to provide some theoretical guidance for clinical operation.

Comparison of Clinical and Anatomical Outcomes between Delaminated Rotator Cuff Tear and Single Layer Rotator Cuff Tear

BACKGROUND: Delaminated rotator cuff tear is known to be a degenerative tear having a negative prognostic effect. This study undertook to compare the anatomical and clinical outcomes of delaminated tears and single layer tears. METHODS: Totally, 175 patients with medium to large rotator cuff tears enrolled for the study were divided into 2 groups, based on the tear pathology: single layer tear (group 1) and delaminated tear (group 2). Preoperatively, length of the remnant tendon, muscle atrophy of supraspinatus (SS), and fatty degeneration of SS and infraspinatus (IS) muscles were assessed on magnetic resonance imaging (MRI). For follow-up, the repair integrity of the rotator cuff was evaluated by ultrasonography. Clinical outcomes were assessed by evaluating the Constant score (CS) and Korean Shoulder Score (KSS). RESULTS: Retears were detected in 6 cases of group 1 (6.5%) and 11 cases of group 2 (13.3%). Although higher in group 2, the retear rate was significantly not different (p=0.133). Preoperative MRI revealed length of remnant tendon to be 15.46 ± 3.60 mm and 14.17 ± 3.16 mm (p=0.013), and muscle atrophy of SS (occupation ratio) was 60.54 ± 13.15 and 56.55 ± 12.88 (p=0.045), in group 1 and group 2, respectively. Fatty degeneration of SS and IS in both groups had no significant differences. Postoperatively, no significant differences were observed for CS and KSS values between the groups. CONCLUSIONS: Delaminated rotator cuff tears showed shorter remnant tendon length and higher muscle atrophy that correlate to a negative prognosis. These prognostic effects should be considered during delaminated rotator cuff tear treatment.

New Retear Pattern after Rotator Cuff Repair at Previous Intact Portion of Rotator Cuff

Retear patterns after arthroscopic rotator cuff repair are classified into two patterns according to retear location. Type 1 is when the retear pattern occurs directly on the tendon at the bone repair site using the suture anchor repair method. Type 2 is when the retear pattern occurs at the musculocutaneous junction with a healed footprint in patients who undergo the suture bridge method. Here, the authors report another retear pattern, which was identified as a type 2 retear on magnetic resonance imaging in patients who had undergone arthroscopic rotator cuff repair by the suture-bridge technique. This pattern was different from the type 2 retear and occurred at the portion of the cuff away from the healed rotator cuff under the view of the arthroscope.

New Retear Pattern after Rotator Cuff Repair at Previous Intact Portion of Rotator Cuff

Retear patterns after arthroscopic rotator cuff repair are classified into two patterns according to retear location. Type 1 is when the retear pattern occurs directly on the tendon at the bone repair site using the suture anchor repair method. Type 2 is when the retear pattern occurs at the musculocutaneous junction with a healed footprint in patients who undergo the suture bridge method. Here, the authors report another retear pattern, which was identified as a type 2 retear on magnetic resonance imaging in patients who had undergone arthroscopic rotator cuff repair by the suture-bridge technique. This pattern was different from the type 2 retear and occurred at the portion of the cuff away from the healed rotator cuff under the view of the arthroscope.

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.

A Comparison of Conventional Ultrasonography and Arthrosonography in the Assessment of Cuff Integrity after Rotator Cuff Repair

BACKGROUND: This study was designed to perform conventional ultrasonography, magnetic resonance arthrography (MRA) and arthrosonography exams after rotator cuff repair to compare the results of conventional ultrasonography and arthrosonography with those of MRA as the gold standard. METHODS: We prospectively studied 42 consecutive patients (14 males, 28 females; average age, 59.4 years) who received arthroscopic rotator cuff repair due to full-thickness tears of the supraspinatus tendon from 2008 to 2010. The integrity assessment of the repaired rotator cuff was performed 6 months postoperatively using conventional ultrasonography, MRA, and arthrosonography. RESULTS: The diagnostic accuracy of the conventional ultrasonography compared to MRA was 78.6% and the McNemar test results were 0.016 in full-thickness tear and 0.077 in partial-thickness tear. The diagnostic accuracy of arthrosonography compared to MRA was 92.9% and the McNemar test results were 0.998 in full-thickness tear and 0.875 in partial-thickness tear. CONCLUSIONS: It was found that the integrity assessment of the repaired rotator cuff by ultrasonography must be guarded against and that arthrosonography is an effective alternative method in the postoperative integrity assessment. Also, an arthrosonography seems to be a suitable modality to replace the conventional ultrasonography.

Clinical and Radiological Evaluation after Arthroscopic Rotator Cuff Repair Using Suture Bridge Technique

BACKGROUND: We retrospectively assessed the clinical outcomes and investigated risk factors influencing retear after arthroscopic suture bridge repair technique for rotator cuff tear through clinical assessment and magnetic resonance arthrography (MRA). METHODS: Between January 2008 and April 2011, sixty-two cases of full-thickness rotator cuff tear were treated with arthroscopic suture bridge repair technique and follow-up MRA were performed. The mean age was 56.1 years, and mean follow-up period was 27.4 months. Clinical and functional outcomes were assessed using range of motion, Korean shoulder score, Constant score, and UCLA score. Radiological outcome was evaluated with preoperative and follow-up MRA. Potential predictive factors that influenced cuff retear, such as age, gender, geometric patterns of tear, size of cuff tear, acromioplasty, fatty degeneration, atrophy of cuff muscle, retraction of supraspinatus, involved muscles of cuff and osteolysis around the suture anchor were evaluated. RESULTS: Thirty cases (48.4%) revealed retear on MRA. In univariable analysis, retear was significantly more frequent in over 60 years age group (62.5%) than under 60 years age group (39.5%; p = 0.043), and also in medium to large-sized tear than small-sized tear (p = 0.003). There was significant difference in geometric pattern of tear (p = 0.015). In multivariable analysis, only age (p = 0.036) and size of tear (p = 0.030) revealed a significant difference. The mean active range of motion for forward flexion, abduction, external rotation at the side and internal rotation at the side were significantly improved at follow-up (p 0.05). The locations of retear were insertion site in 10 cases (33.3%) and musculotendinous junction in 20 cases (66.7%; p = 0.006). CONCLUSIONS: Suture bridge repair technique for rotator cuff tear showed improved clinical results. Cuff integrity after repair did not affect clinical results. Age of over 60 years and size of cuff tear larger than 1 cm were factors influencing rotator cuff retear after arthroscopic suture bridge repair technique.

Massive Rotator Cuff Tear Repair

PURPOSE: Anatomical repair of massive rotator cuff tear has been technically challenging because of medial retraction, muscle atrophy and fatty degeneration. Among several treatment options for massive rotator cuff tear, we reviewed rotator cuff repairs and investigated modalities for improvement of clinical outcomes, decreasing the re-tear rate, and increasing healing. MATERIALS AND METHODS: Patient-related factors and rotator cuff-related factors were the two major groups of factors we considered when choosing a treatment plan. RESULTS: Mobilization of a massive rotator cuff tear was increased by soft tissue release and by the interval slide technique. After meticulous soft tissue release, anatomical repair could be achieved. If the injury was not amenable to anatomical repair, alternative treatment options such as partial repair, the margin convergence technique and augmentation with a tenotomized biceps tendon were considered. Many reports of massive rotator cuff repair demonstrated satisfactory clinical outcomes, decreased pain, recovery of shoulder functions, and increases in muscle strength. However, the re-tear rate had been reported to be relatively high in long-term follow-up. CONCLUSION: Despite a high re-tear rate after massive rotator cuff repair, a better understanding of the pathogenesis, progression and clinical symptoms of massive rotator cuff tear and improved surgical materials and techniques will lead to satisfactory clinical outcomes.

The Radiologic and Clinical Changes after Open Complete Repair of Massive Rotator Cuff Tears

PURPOSE: This study evaluated the preoperative and postoperative radiologic findings of patients with complete repairs after massive rotator cuff tears along with the incidence of re-tear and the clinical outcomes. MATERIALS AND METHODS: This study evaluated 33 cases who had open complete repairs for massive rotator cuff tears and these patients were followed up for more than 24 months. The clinical evaluation was performed according to the shoulder joint function test of the American Shoulder and Elbow Surgeons (ASES), and the degree of arthritis related to the massive rotator cuff tears was evaluated using the Hamada classification. RESULTS: The ASES scores improved from 37.6 preoperatively to 85.6 postoperatively. The mean preoperative acromio-humeral interval (AHI) score was 6.5 mm, which increased to 9.3 mm immediately after surgery, and there was a decreased to 6.5 mm noted at the last follow up. The lower radiology stages of arthritis according to the classification showed better preoperative and postoperative results. CONCLUSION: An open complete repair as the surgical treatment for a massive rotator cuff tear showed satisfactory results for pain relief and an improvement in the shoulder joint function though re-tear after surgery.

The Factors Affecting the Clinical Outcome and Integrity of Arthroscopically Repaired Rotator Cuff Tears of the Shoulder

BACKGROUND: The purpose of this study was to evaluate the functional and anatomic results of arthroscopic rotator cuff repair, and to analyze the factors affecting the integrity of arthroscopically repaired rotator cuff tears of the shoulder. METHODS: One hundred sixty-nine consecutive shoulders that underwent arthroscopic rotator cuff repair, had a postoperative MRI evaluation and were followed for at least two years were enrolled in this study. The mean age was 57.6 years (range, 38 to 74 years) and the mean follow-up period was 39 months (range, 24 to 83 months). RESULTS: The rotator cuff was completely healed in 131 (77.5%) out of 169 shoulders and recurrent tears occurred in 38 shoulders (22.5%). At the last follow-up visit, the mean score for pain during motion was 1.53 (range, 0 to 4) in the completely healed group and 1.59 (range, 0 to 4) in the group with recurrent tears (p = 0.092). The average elevation strength was 7.87 kg (range, 4.96 to 11.62 kg) and 5.25 kg (range, 4.15 to 8.13 kg) and the mean University of California at Los Angeles score was 30.96 (range, 26 to 35) and 30.64 (range, 23 to 34), respectively (p < 0.001, p = 0.798). The complete healing rate was 87.8% in the group less than 50 years of age (49 shoulders), 79.4% in the group over 51 years but less than 60 years of age (68 shoulders), and 65.4% in the group over 61 years of age (52 shoulders, p = 0.049); it was 96.7% in the group with small-sized tears (30 shoulders), 87.3% in the group with medium-sized tears (71 shoulders), and 58.8% in the group with large-sized or massive tears (68 shoulders, p = 0.009). All of the rotator cuffs with a global fatty degeneration index of greater than two preoperatively had recurrent tears. CONCLUSIONS: Arthroscopic repair of full-thickness rotator cuff tears led to a relatively high rate of recurrent defects. However, the minimum two-year follow up demonstrated excellent pain relief and improvement in the ability to perform the activities of daily living, despite the structural failures. The factors affecting tendon healing were the patient's age, the size and extent of the tear, and the presence of fatty degeneration in the rotator cuff muscle.

MRI Follow-up Study After Arthroscopic Repair of Multiple Rotator Cuff Tendons

PURPOSE: This study investigated the rate of retear and related factors after arthroscopic repair of rotator cuff tears involving more than one tendon. MATERIALS & METHODS: Arthroscopic repair of 22 rotator cuff tears (average size 3.2cm: average age 58 years old) involving the supraspinatus and part or all of the infraspinatus were investigated using MRI on average 10 months after repair. The status of the repaired cuff was investigated using Sugaya's classification, and the change in muscle was evaluated with Goutallier's classification. RESULTS: Retear (Sugaya grade IV, V) was found in 7cases(32%). Tears larger than 3cm had a higher retear rate(67%) than smaller tears(8%). Retear cases had Goutallier grade II or higher muscle changes preoperatively and showed aggravation of muscle atrophy postoperatively. Even without retear, reversal of muscle change was not seen CONCLUSION: Rotator cuff tears not confined to the supraspinatus had a 32% retear rate after arthroscopic repair. The size of the tear was the most crucial factor influencing retear. Retear was frequent in tear over 3cm. Atrophy of the cuff muscle worsened when the repair failed but did not improve even without retear.