[Modified Latarjet splitting subscapularis muscle under arthroscopy: an anatomical study based on axillary nerve, glenoid, and subscapularis muscle].

Objective: To testify the spatial relationship between the subscapularis muscle splitting window and the axillary nerve in modified arthroscopic Latarjet procedure, which could provide anatomical basis for the modification of the subscapularis muscle splitting. Methods: A total of 29 adult cadaveric shoulder specimens were dissected layer by layer, and the axillary nerve was finally confirmed to walk on the front surface of the subscapularis muscle. Keeping the shoulder joint in a neutral position, the Kirschner wire was passed through the subscapularis muscle from back to front at the 4 : 00 position of the right glenoid circle (7 : 00 position of the left glenoid circle), and the anterior exit point (point A, the point of splitting subscapularis muscle during Latarjet procedure) was recorded. The vertical and horizontal distances between point A and the axillary nerve were measured respectively. Results: In the neutral position of the shoulder joint, the distance between the point A and the axillary nerve was 27.37 (19.80, 34.55) mm in the horizontal plane and 16.67 (12.85, 20.35) mm in the vertical plane. Conclusion: In the neutral position of the shoulder joint, the possibility of axillary nerve injury will be relatively reduced when radiofrequency is taken from the 4 : 00 position of the right glenoid (7 : 00 position of the left glenoid circle), passing through the subscapularis muscle posteriorly and anteriorly and splitting outward.

[Radiographic study of effect of lateral placement of bone graft on shoulder joint degeneration after modified arthroscopic Latarjet surgery with elastic fixation].

OBJECTIVE: To investigate the mid-term effect of lateral placement of bone graft on shoulder joint degeneration after modified arthroscopic Latarjet surgery with elastic fixation for recurrent anterior shoulder dislocation with an anterior glenoid bone defect. METHODS: According to the inclusion and exclusion criteria, 18 patients with recurrent anterior shoulder dislocation and anterior glenoid bone defect who received the modified arthroscopic Latarjet surgery with elastic fixation between January 2015 and November 2016 were enrolled in this study. There were 12 males and 6 females with an average age of 26.2 years (range, 19-37 years). The number of shoulder dislocation ranged from 4 to 30 times (mean, 8.8 times). The disease duration was 8-49 months (mean, 23.8 months). The mean anterior glenoid bone defect was 25.2% of the glenoid surface (range, 20%-29%). The mean preoperative Instability Severity Index Score (ISIS) was 7.6 (range, 7-10). According to Samilson-Prieto classification, the shoulder joint degeneration was rated as grade 0 in 13 cases, grade Ⅰ in 3 cases, and grade Ⅱ in 2 cases. Before and after operation, the visual analogue scale (VAS) score, American Society of Shoulder and Elbow Surgery (ASES) score, Walch-Duplay score, Rowe score, and shoulder mobility were used to evaluate the effectiveness. Imaging examination was performed to observe the shoulder joint degeneration, the position of the bone graft, and the postoperative shaping of the scapular glenoid. RESULTS: All patients were followed up 55-62 months, with an average of 59.6 months. There was no neurovascular injuries, infections, fixation-related and bone graft-related complications. No re-dislocation and revision occurred. All patients returned to normal life, 17 of whom returned to sport. The VAS score was significantly decreased and ASES, Walch-Duplay, and Rowe scores were significantly improved at last follow-up ( P<0.05). No significant difference was found in range of motion of forward flexion, abduction, lateral rotation at 90° abduction, internal rotation at 90° abduction, or lateral rotation at 0° between pre- and post-operation ( P>0.05). Three-dimensional CT showed that the centers of all bone grafts were between 3∶30 and 4∶30 (right shoulder) or between 7∶40 and 8∶20 (left shoulder) and no bone grafts were positioned superiorly or inferiorly in the glenoid En-face view. All bone grafts were positioned lateral to the scapular glenoid with an average distance of 3.5 mm (range, 2.3-4.6 mm) in cross-sectional imaging by CT. Compared with the preoperative Samilson-Prieto classification results, all cases showed no progression of shoulder joint degeneration at 36, 48 months and last follow-up. All bone grafts remodeled to a steady state within 24 months after operation. The bone graft and glenoid finally remodeled analogous to the shape of the intact glenoid in the En-face view and became flush with the glenoid rim, remodeling to a curved shape congruent to the humeral head in cross-sectional imaging by CT. The shape of the remodeled glenoid at last follow-up was not significantly different from that at 24 months after operation. CONCLUSION: The lateral placement of the bone graft during modified arthroscopic Latarjet surgery with elastic fixation do not accelerate the imaging changes of shoulder joint degeneration.

Interbundle Impingement Pressure in Individualized and Nonindividualized Double-Bundle Anterior Cruciate Ligament Reconstruction: A Cadaveric Study.

BACKGROUND: Graft impingement is one of the main concerns in double-bundle anterior cruciate ligament reconstruction (DB-ACLR). Impingement between the anteromedial (AM) and posterolateral (PL) bundles has been postulated to cause graft deterioration or rerupture, but this has not been thoroughly investigated, and the interbundle impingement pressure (IIP) has not been well researched. PURPOSE: To determine the IIP between the AM and PL bundles in the native anterior cruciate ligament (ACL) and in DB-ACLR with individualized and nonindividualized double-tunnel placement. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 30 fresh-frozen, nonpaired, human cadaveric knees were randomly divided into 3 groups of 10 knees: native intact ACL (NI group), DB-ACLR tunnel placement using the preserved remnant procedure (individualized reconstruction) (PR group), and DB-ACLR tunnel placement using the bony landmark procedure (nonindividualized reconstruction) (BL group). Pressure sensors were inserted between the AM and PL bundles. The knee was moved passively from full extension to full flexion, and the IIP between the 2 ACL bundles was measured every 15°. Similarly, the impingement pressure was measured between the ACL and intercondylar roof and between the ACL and posterior cruciate ligament (PCL). RESULTS: No significant differences were found in the maximum, mean, or minimum ACL-roof and ACL-PCL impingement pressures among the 3 groups. The IIP significantly increased when the knee joint was flexed >120° in all 3 groups (P < .001). Compared with the other 2 groups, the BL group had significantly higher maximum and mean IIP throughout the range of knee movement (P < .001) and from maximum extension to 120° of flexion (P < .001). The BL group also had significantly higher minimum IIP than the other 2 groups when knee flexion was >120° (P < .001). No significant differences were seen in maximum, minimum, or mean IIP between the NI and PR groups. CONCLUSION: The PR procedure (individualized DB-ACLR) was more consistent with the interbundle biomechanical conditions of the native ACL, whereas the BL procedure (nonindividualized DB-ACLR) had higher maximum and mean IIP. The IIP was higher than the ACL-intercondylar roof or ACL-PCL pressures, and it increased significantly when knee flexion was >120°. CLINICAL RELEVANCE: These data suggest that surgeons can perform individualized DB-ACLR using preserved remnants for tunnel placement as impingement-free DB-ACLR.

[Biomechanical comparative analysis of screw fixation and cortical endo-button fixation in Latarjet procedure for anterior dislocation of shoulder joint].

OBJECTIVE: To clarify the value of the cortical endo-button as an internal fixator in Latarjet procedure through biomechanical analysis. METHODS: Ten pairs of shoulder joints from 6-7 months old male pigs were selected. Each pair was randomly divided into screw group and endo-button group. A 25% glenoid defect model was created, and the porcine infraspinatus tendon and its associated bone were used to simulate conjoint tendon and coracoid process in human body. The bone grafts were fixed with two 3.5 mm screws and double cortical endo-buttons with high-strength sutures in screw group and endo-button group, respectively. The prepared glenoid defect model was fixed on a biomechanical test bench and optical markers were fixed on the glenoid and the bone block, respectively. Then fatigue test was performed to observe whether the graft or internal fixator would failed. During the test, the standard deviations of the relative displacement between the graft and the glenoid of two groups were measured by optical motion measure system for comparison. Finally the maximum failure load comparison was conducted and the maximum failure loads of the two groups were measured and compared. RESULTS: There was no tendon tear, bone fracture, and other graft or internal fixation failure in the two groups during the fatigue test. The standard deviation of the relative displacement of the screw group was (0.007 87±0.001 44) mm, and that of the endo-button group was (0.034 88±0.011 10) mm, showing significant difference between the two groups ( t=7.682, P=0.000). The maximum failure load was (265±39) N in screw group and (275±52) N in endo-button group, showing no significant difference between the two groups ( t=1.386, P=0.199). There were 3 ways of failure: rupture at bone graft's tunnel (6/10 from screw group, 3/10 from endo-button group), tendon tear at the cramp (2/10 from screw group, 2/10 from endo-button group), and tendon tear at the internal fixator interface (2/10 from screw group, 5/10 from endo-button group), showing no significant difference between the two groups ( P=0.395). CONCLUSION: Although the endo-button fixation fails to achieve the same strong fixation stability as the screw fixation, its fixation stability can achieve the clinical requirements. The two fixation methods can provide similar fixation strength when being used in Latarjet procedure.

[A correlation study between the Mohawk expression level and the collagen fiber diameter of hamstring tendon graft after anterior cruciate ligament reconstruction].

OBJECTIVE: To evaluate the correlation between the Mohawk (MKX) expression level and the collagen fiber diameter of autologous hamstring tendon graft during the stable graft remodeling phase after anterior cruciate ligament (ACL) reconstruction. METHODS: Between January 2018 and August 2018, patients who underwent arth-roscopic single-bundle anatomical ACL reconstruction with autologous hamstring tendons for at least 48 months and also underwent second-look arthroscopy were enrolled in study. During the second-look arthroscopic procedures, ACL graft biopsies were performed from the surface of central part of the ligament. MKX expressions of ACL grafts were analysed by real-time fluorescent quantitative PCR (qRT-PCR). The ultrastructure of collagen fibers of grafts were evaluated by transmission electron microscopy, which included average diameter of collagen fibers (D c), average diameter of large-diameter collagen fibers (D L), average diameter of small-diameter collagen fibers (D S), and large-small collagen fibers ratio (R L/S). The correlation between MKX expression level and graft collagen fiber diameter was calculated. RESULTS: Twenty-six patients met the selection criteria and their ACL graft specimens were enrolled in the study. The interval between ACL reconstruction and second-look arthroscopy was 52-128 months, with an average of 78.6 months. Arthroscopic graft remodeling score was 3-6 (mean, 4.8). There were 17 cases of excellent remodeling and 9 cases of fair remodeling. All ACL grafts showed typical bimodal distributions of both large-diameter collagen fibers and small-diameter collagen fibers, but the ultrastructural characteristics of the graft collagen fibers were different according to different remodeling status under arthroscopy. The D C, D L, D S, and R L/S of the graft specimens were (65.2±9.3) nm, (91.6±10.5) nm, (45.7±8.6) nm, and 0.73±0.12, respectively. The relative expression level of MKX was 1.42±0.11, which was positively linearly correlated with D C, D L, and R L/S, and the correlation coefficient was statistically significant ( r=0.809, P=0.000; r=0.861, P=0.000; r=0.942, P=0.000), while there was no significant correlation between D S and relative expression level of MKX ( r=0.147, P=0.238). Regression analysis showed that the relative expression level of MKX could predict the D C, D L, and R L/S results of the ACL graft specimens ( P<0.05). CONCLUSION: After autologous hamstring tendon grafts stepped into stabilized remodeling phase, MKX expression level could predict the diameter measurement results of collagen fibers and be used as an important evaluation basis for graft collagen anabolic metabolism.

[Research progress of surgical treatment for anterior shoulder dislocation and combined injuries].

OBJECTIVE: To summarize the research progress of surgical treatment for anterior shoulder dislocation and combined injuries. METHODS: The related literature was reviewed, and the surgical treatment options for the anterior shoulder dislocation and its combined injuries were summarized. RESULTS: Anterior shoulder dislocation can combine with anteroinferior capsular ligament complex injury (Bankart injury), bony Bankart defect, and Hill-Sachs lesion. For Bankart and bony Bankart injuries, arthroscopic repair or coracoid osteotomy combined with bony graft reconstruction can be performed. For Hill-Sachs lesion, conservative treatment, soft tissue repair, or bony reconstruction should be selected based on the extent of the bone defect. For bipolar injury, the Bankart repair, Remplissage, or arthroplasty should be selected based on the extent of the glenoid defect. CONCLUSION: With the development of arthroscopy and the improvement of the surgical concept, there is a complete set of surgical options for various injuries of the anterior shoulder dislocation. When choosing a surgical procedure, the patient's specific injury and age, exercise level, and other relating factors should be comprehensively assessed in order to achieve the best results.

[Histological properties of autogenous hamstring grafts after anterior cruciate ligament reconstruction].

Objective: To investigate the histological characteristics of autogenous hamstring grafts after anterior cruciate ligament (ACL) reconstruction. Methods: The patients who underwent arthroscopic single-bundle ACL reconstruction with autogenous hamstring tendons and were followed up at least 4 years and also underwent second-look arthroscopy between March 2017 and December 2017 and met the selection criteria were considered for enrollment. Graft quality under arthroscopy was evaluated as good remodeling group (GRG, the total scores were 4-6) and poor remodeling group (PRG, the total scores were 1-3) according to synovial and vascular coverage, the apparent tension of the grafts, the thickness and retear of the grafts. During the second-look arthroscopic procedures, ACL graft biopsies were performed. Normal ACL tissues harvested from the patients under 60 years old who underwent total knee arthroplasty were designated as normal controls. Graft vascularity, cellular morphology, cellular metabolism, and collagen fibril distribution were analyzed. Results: The 18 specimens (11 cases of GRG group and 7 cases of PRG group) and 9 native ACL biopsied tissue sample were enrolled into the study. Arthroscopy scores were 2-6 (mean, 4.7). The biology under light microscopy of GRG group was similar to that of native ACL in control group. There was no significant difference in the scores of graft vascularity and cellular morphology between GRG group and control group ( P>0.05), while PRG group was significantly lower than the other two groups ( P<0.05). Transmission electron microscope evaluation showed that GRG group and control group had better collagen fibril distribution and lower levels of cellular metabolism than PRG group ( P<0.05). There was no significant difference in cellular metabolism between GRG and control groups ( P>0.05), while collagen fibril distribution score of GRG group was significantly lower than that of control group ( P<0.05). Conclusion: While good remodeling grafts under arthroscopy in histological maturation period was proved to be more similar to normal ACL on ultrastructure properties under light and electron microscope, ultra structural differences regarding collagen fibril distribution still persist.