Three-dimensional evaluation of cyclic displacement in single-row and double-row rotator cuff reconstructions under static external rotation.

BACKGROUND: The double-row suture bridge repair was recently introduced and has demonstrated superior biomechanical results and higher yield load compared with the traditional double-row technique. It therefore seemed reasonable to compare this second generation of double-row constructs to the modified single-row double mattress reconstruction. HYPOTHESIS: The repair technique, initial tear size, and tendon subregion will have a significant effect on 3-dimensional (3D) cyclic displacement under additional static external rotation of a modified single-row compared with a double-row rotator cuff repair. STUDY DESIGN: Controlled laboratory study. METHODS: Rotator cuff tears (small to medium: 25 mm; medium to large: 35 mm) were created in 24 human cadaveric shoulders. Rotator cuff repairs were performed as modified single-row or double-row repairs, and cyclic loading (10-60 N, 10-100 N) was applied under 20° of external rotation. Radiostereometric analysis was used to calculate cyclic displacement in the anteroposterior (x), craniocaudal (y), and mediolateral (z) planes with a focus on the repair constructs and the initial tear size. Moreover, differences in cyclic displacement of the anterior compared with the posterior tendon subregions were calculated. RESULTS: Significantly lower cyclic displacement was seen in small to medium tears for the single-row compared with double-row repair at 60 and 100 N in the x plane (P = .001) and y plane (P = .001). The results were similar in medium to large tears at 100 N in the x plane (P = .004). Comparison of 25-mm versus 35-mm tears did not show any statistically significant differences for the single-row repairs. In the double-row repairs, lower gap formation was found for the 35-mm tears (P ≤ .05). Comparison of the anterior versus posterior tendon subregions revealed a trend toward higher anterior gap formation, although this was statistically not significant. CONCLUSION: The tested single-row reconstruction achieved superior results in 3D cyclic displacement to the tested double-row repair. Extension of the initial rupture size did not have a negative effect on the biomechanical results of the tested constructs. CLINICAL RELEVANCE: Single-row repairs with modified suture configurations provide comparable biomechanical strength to double-row repairs. Furthermore, as increased gap formation in the early postoperative period might lead to failure of the construct, a strong anterior fixation and restricted external rotation protocol might be considered in rotator cuff repairs to avoid this problem.

Comparable biomechanical results for a modified single-row rotator cuff reconstruction using triple-loaded suture anchors versus a suture-bridging double-row repair.

PURPOSE: To compare the biomechanical properties and footprint coverage of a single-row (SR) repair using a modified suture configuration versus a double-row (DR) suture-bridge repair in small to medium and medium to large rotator cuff tears. METHODS: We created 25- and 35-mm artificial defects in the rotator cuff of 24 human cadaveric shoulders. The reconstructions were performed as either an SR repair with triple-loaded suture anchors (2 to 3 anchors) and a modified suture configuration or a modified suture-bridge DR repair (4 to 6 anchors). Reconstructions were cyclically loaded from 10 to 60 N. The load was increased stepwise up to 100, 180, and 250 N. Cyclic displacement and load to failure were determined. Furthermore, footprint widths were quantified. RESULTS: In the 25-mm rupture, ultimate load to failure was 533 ± 107 N for the SR repair and 681 ± 250 N for the DR technique (P ≥ .21). In the 35-mm tear, ultimate load to failure was 792 ± 122 N for the SR reconstruction and 891 ± 174 N for the DR reconstruction (P ≥ .28). There were no statistically significant differences for both tested rupture sizes. Cyclic displacement showed no significant differences between the tested configurations at 60 N (P = .563), 100 N (P = .171), 180 N (P = .211), and 250 N (P = .478) for the 25-mm tear. For the 35-mm tear, cyclic displacement showed significantly lower gap formation for the SR reconstruction at 180 N (P = .037) and 250 N (P = .020). No significant differences were found at 60 N (P = .296) and 100 N (P = .077). A significantly greater footprint width (P = .028) was seen for the DR repair (16.2 mm) compared with the SR repair (13.8 mm). However, both reconstructions were able to achieve complete footprint coverage compared with the initial footprint. CONCLUSIONS: The tested SR repair using a modified suture configuration was similar in load to failure and cyclic displacement to the DR suture-bridge technique independent of the tested initial sizes of the rupture. The tested DR repair consistently restored a larger footprint than the SR method. However, both constructs achieved complete footprint coverage. CLINICAL RELEVANCE: SR repairs with modified suture configurations might combine the biomechanical advantages and increased footprint coverage that are described for DR repairs without increasing the overall costs of the reconstruction.

Anatomy of the superior glenohumeral ligament.

BACKGROUND: The aim of the present study was to give a detailed, anatomical description of the superior glenohumeral ligament and its relationship with the neighbouring structures in the rotator interval. METHOD: Twenty-seven cadaveric shoulder specimens were dissected in fine detail to describe superior glenohumeral ligament and additional histologic examination was performed. RESULTS: The superior glenohumeral ligament is a constant, gross anatomic structure that was present in all of twenty-seven investigated specimens. The fibers of the superior glenohumeral ligament could be divided into two groups - the oblique and direct fibers. The direct fibers of the superior glenohumeral ligament arise from the glenoid labrum, run parallel with the tendon of the long head of the biceps brachii towards the lesser tubercle, which they also partly insert onto. The rest of the direct fibers course into the bottom of the bicipital groove and bridge over it, forming the superior part of the transverse humeral ligament. The oblique fibers arise from the supraglenoid tubercle, run over the intraarticular part of the tendon of the long head of the biceps brachii and insert below the coracohumeral ligament into the humeral semicircular ligament. CONCLUSION: Due to its anatomic composition and tight connection with the neighboring articular structures, the superior glenohumeral ligament is involved in the stabilizing mechanisms of the intraarticular part of the tendon of the long head of the biceps brachii and plays an important role in the variety of clinical disorders that occur within the rotator interval.

Influence of the anteromedial and posterolateral bundles of the anterior cruciate ligament on external and internal tibiofemoral rotation.

BACKGROUND: The influence of the anteromedial and posterolateral bundles of the anterior cruciate ligament on tibiofemoral rotation might be of great value to detect anterior cruciate ligament injuries and investigate the postoperative restoration of rotational stability. HYPOTHESIS: The anterior cruciate ligament and especially the posterolateral bundle will have a significant influence on isolated tibiofemoral rotation. STUDY DESIGN: Controlled laboratory study. METHODS: Tibiofemoral rotation was measured in 20 human cadaveric knees using a noninvasive external measurement device (Rotameter) and a knee navigation system. The measurements of the knees with the intact anterior cruciate ligament were compared with the measurements after isolated resection of the posterolateral bundle and after a complete resection of the anterior cruciate ligament at an applied torque of 5,10, and 15 N.m. Statistical analysis was made using analysis of variance and the post hoc Scheffé test. The Pearson coefficient was used to compare both measurement techniques. RESULTS: In comparison with knees with an intact anterior cruciate ligament, the knees after isolated resection of the posterolateral bundle showed significant increase of tibiofemoral rotation at almost all applied torques (P <.05). Total resection of the anterior cruciate ligament also produced significant increases compared with the intact anterior cruciate ligament at torques of 5, 10, and 15 N.m as measured by the Rotameter (P <.05). Total resection of the anterior cruciate ligament yielded increases in rotation compared with posterolateral bundle resection alone, but these differences were not significant. The results of the knee navigation system confirmed the measured results of the Rotameter. Comparison of the 2 measurement methods revealed a high correlation at all applied torques, with Pearson correlation coefficients ranging from .85 to .95. CONCLUSION: The anterior cruciate ligament and especially the posterolateral bundle of the anterior cruciate ligament have a significant effect on isolated tibiofemoral rotation. Therefore, the developed noninvasive device might be of great importance to investigate the status and the postoperative reconstruction of the anterior cruciate ligament in the clinical setting. CLINICAL RELEVANCE: Noninvasive measurement of tibiofemoral rotation might be useful to detect anterior cruciate ligament tears and to evaluate the restoration of rotational stability after anterior cruciate ligament surgery.

Effect of a biplanar osteotomy on primary stability following high tibial osteotomy: a biomechanical cadaver study.

Open-wedge high tibial osteotomy (HTO) is becoming increasingly popular for the treatment of varus gonarthrosis in the active patient. The various implants used in HTO differ with regard to its design, the fixation stability and osteotomy technique. It is assumed that the combination of a plate fixator with a biplanar, v-shaped osteotomy supports bone healing. So far, there are no biomechanical studies that quantify the stabilizing effect of a biplanar versus uniplanar osteotomy. We hypothesized that a significant increase in primary stability of bone-implant constructs is achieved when using a biplanar as opposed to a uniplanar osteotomy. Twenty-four fresh-frozen human tibiae were mounted in a metal cylinder, and open-wedge osteotomy (12 mm wedge size) was performed in a standardized fashion. Proximal and distal tibial segments were marked with tantalum markers of 0.8 mm diameter. Two different plates with locking screws were used for fixation: a short spacer plate (group 1, n = 12) and a plate fixator (group 2, n = 12). In six specimens of each group, a biplanar V-shaped osteotomy with a 110 degrees angulated anterior cut behind the tuberosity parallel to the ventral tibial shaft axis was performed. In the remaining six specimens of each group, a simple uniplanar osteotomy was performed in an oblique fashion. Axial compression of the tibiae was performed using a material testing machine under standardized alignment of the loading axis. Load-controlled cyclical staircase loading tests were performed. The specimens were radiographed simultaneously in two planes together with a biplanar calibration cage in front of a film plane with and without load after each subcycle. Radiostereometry allowed for serial quantification of plastic and elastic micromotion at the osteotomy site reflecting the stability provided by the combination of implant and osteotomy technique. No significant additional stabilizing effect of a biplanar osteotomy in craniocaudal and mediolateral plane was found. However, additional stability was achieved in anteroposterior (AP) and all rotational planes in those specimens fixated with a short spacer plate. In this biomechanical set-up with axial load, the additional stabilizing effect of a biplanar osteotomy did not come into effect in the presence of a long and rigid plate fixator. However, biplanar osteotomy increased the fixation stability significantly in AP and rotational planes when a short spacer plate was used. Clinically, the biplanar osteotomy promotes bone healing regardless of the implant used. Biomechanically, biplanar osteotomy is advantageous for shorter plate designs to increase primary stability of the bone-implant construct.

A mouse translocation associated with Caspr5-2 disruption and perinatal lethality.

We have previously described the paralogous mouse genes Caspr5-1, -2, and -3 of the neurexin gene family. Here we present the cytogenetic and molecular mapping of a null mutation of Caspr5-2 which was caused by reciprocal translocation between chromosomes 1 and 8 with breakpoints at bands 1E2.1 and 8B2.1, respectively. The translocation disrupts Caspr5-2 between exons 1 and 2 and causes stillbirth or early postnatal lethality of homozygous carriers. Because no other candidate genes were found, the disruption of Caspr5-2 is most likely the cause of lethality. Only rarely do homozygotes survive the critical stage, reach fertility, and are then apparently normal. They may be rescued by one of the two other Caspr5 paralogs. Caspr5-2 is expressed in spinal cord and brain tissues. Despite giving special attention to regions where in wild-type fetuses maximum expression was found, no malformation that might have caused death could be detected in fetal homozygous carriers of the translocation. We, therefore, suspect that Caspr5-2 disruption leads to dysfunction at the cellular level rather than at the level of organ development.

The spiral glenohumeral ligament: an open and arthroscopic anatomy study.

PURPOSE: The purpose of this study was to visualize arthroscopically and to describe the micro- and macroscopic anatomy of the poorly known ligament of the anterior capsule of the glenohumeral joint: the so-called ligamentum glenohumerale spirale (spiral GHL). METHODS: Twenty-two fresh shoulder joints were dissected, and the anatomy of the anterior capsular structures (the spiral GHL, the middle glenohumeral ligament [MGHL], and the anterior band as well as the axillary part of the inferior glenohumeral ligament [AIGHL and AxIGHL, respectively]) was investigated. For arthroscopic visualization, 30 prospective arthroscopic clinical cases and 19 retrospective video clips of the patients who had an arthroscopic shoulder procedure with a normal subscapularis tendon, labrum, and anterior joint capsule were evaluated. RESULTS: The spiral GHL and the AxIGHL were present in all 22 shoulder specimens. The AIGHL was not recognizable on the extra-articular side of the joint capsule. The MGHL was absent in 3 shoulder specimens (13.6%). Arthroscopically, the spiral GHL was found in 22 (44.9%), the MGHL in 43 (87.8%), and the AIGHL in 46 (93.9%) of the cases. The spiral GHL arose from the infraglenoid tubercle and the triceps tendon and inserted together with subscapularis tendon onto the lesser tubercle of the humerus. CONCLUSIONS: Our results suggest that extra-articular structure of the spiral GHL is consistently recognizable, the upper part of which can be arthroscopically identified. CLINICAL RELEVANCE: Advanced anatomic knowledge of the spiral GHL helps the clinician better understand the normal anatomy of the shoulder joint and also helps to differentiate it from pathologic findings of the patient. The biomechanical importance of the spiral GHL and its connection with shoulder pathology remains to be determined in further studies.

Magnetic resonance imaging and correlative gross anatomy of the ligamentum semicirculare humeri (rotator cable).

The purpose of this study has been to demonstrate macroscopic and MRI anatomy of the so-called rotator cable, otherwise known as the ligamentum semicirculare humeri (LSCH) of the superior shoulder joint capsule. Twelve shoulder joints from eight cadavers were dissected; seven of which, from four of the cadavers, were studied using MR arthrography (1.5-Tesla device Somatom Symphony, Siemens, Erlangen, Germany) prior to dissection. The MRI protocol included T1WI, PDWI, and DESS 3D WI standard sequences. The results of MRI were compared with gross anatomic dissection findings. The macroscopically recognizable capsular bundle of LSCH fibers was identified by anatomic dissection in all specimens. On MRI, the entire ligament or parts of it could be identified in six of seven cases. It was best visualized on axial images. In the evaluation of magnetic resonance images of superior shoulder joint structures, additional knowledge on the anatomy of the LSCH can be used by the radiologist to facilitate detailed interpretation of the shoulder MRI.

Macroscopical anatomy of the so-called "rotator interval". A cadaver study on 19 shoulder joints.

The triangular capsular space between the insertion tendons of the Mm. supraspinatus and subscapularis--the "rotator interval", can be divided into lateral, medio-superior and medio-inferior parts. The lateral part of the capsule is strengthened by the "Lig. semicirculare humeri" and the anterior fibres of the M. supraspinatus tendon. The Ligg. coracohumerale and "coracoglenoidale" are the macroscopical elements of the medio-superior part. The medio-inferior part of the "rotator interval" is reinforced by the Ligg. glenohumeralia superius et medium. The key ligament of the "rotator interval" is the "Lig. semicirculare humeri". Laterally it ensures the insertion of the anterior fibres of the M. supraspinatus tendon above the Lig. transversum humeri and on the Tubercula majus et minus. Medially it is the place of attachment of the Lig. coracohumerale and oblique fibres of the Lig. glenohumerale superius. The "rotator interval" is not a weak capsular region but a complex network of macroscopically recognizable tendinous and ligamentous structures.