Incorporating BMP-2 and skeletal muscle to a semitendinosus autograft in an oversized tunnel yields robust bone tunnel ossification in rabbits: Toward single-step revision of failed anterior cruciate ligament reconstruction.

BACKGROUND: Bone tunnel widening after anterior cruciate ligament (ACL) reconstruction is a known complication that can lead to graft failure. Subsequent revision surgery typically involves a two-stage procedure. The aim of this study was to test a novel autologous tendon graft retaining muscle tissue combined with Human Recombinant Bone Morphogenetic Protein-2 (rh-BMP-2) leading to rapid ossification of the muscle tissue, simultaneously replenishing bone stock and producing a mechanically stable bone-tendon insertion. METHODS: In 12 skeletally mature New Zealand rabbits, the ACL was resected and oversized bone tunnels were drilled to model tunnel widening. The ipsilateral semitendinosus muscle-tendon graft was harvested and folded twice. Muscle tissue was removed in the middle third but retained at both distal ends. One side was wrapped in a collagen sponge loaded with rh-BMP-2 while the other end was used as its own control. RESULTS: All animals were euthanized after six weeks. Micro-computed tomography (micro-CT) was used to analyze bone formation in 12 animals, with additional biomechanical testing to failure and histology performed for six animals each. Micro-CT showed that bone densities were higher by a factor of 2.4 in treated graft ends compared with their controls. Biomechanical testing showed a mean overall failure load of 37.5 N. Histology showed that the trabecular bone surrounding the implant was significantly (P = 0.0087) thicker on the treated (85.5 µm) compared with the control side (68.2 µm). CONCLUSIONS: We conclude that a semitendinosus graft retaining the muscle tissue stimulated by recombinant Bone Morphogenetic Protein-2 (BMP-2) allows robust osseointegration of the graft within an oversized bone tunnel in an animal model.

Validation of a virtual reality-based simulator for shoulder arthroscopy.

PURPOSE: This study was to determine face and construct validity of a new virtual reality-based shoulder arthroscopy simulator which uses passive haptic feedback. METHODS: Fifty-one participants including 25 novices (<20 shoulder arthroscopies) and 26 experts (>100 shoulder arthroscopies) completed two tests: for assessment of face validity, a questionnaire was filled out concerning quality of simulated reality and training potential using a 7-point Likert scale (range 1-7). Construct validity was tested by comparing simulator metrics (operation time in seconds, camera and grasper pathway in centimetre and grasper openings) between novices and experts test results. RESULTS: Overall simulated reality was rated high with a median value of 5.5 (range 2.8-7) points. Training capacity scored a median value of 5.8 (range 3-7) points. Experts were significantly faster in the diagnostic test with a median of 91 (range 37-208) s than novices with 1177 (range 81-383) s (p < 0.0001) and in the therapeutic test 102 (range 58-283) s versus 229 (range 114-399) s (p < 0.0001). Similar results were seen in the other metric values except in the camera pathway in the therapeutic test. CONCLUSION: The tested simulator achieved high scores in terms of realism and training capability. It reliably discriminated between novices and experts. Further improvements of the simulator, especially in the field of therapeutic arthroscopy, might improve its value as training and assessment tool for shoulder arthroscopy skills. LEVEL OF EVIDENCE: II.

Lengthening of the subscapularis tendon as a sign of partial tearing in continuity.

BACKGROUND: The quantification of a subscapularis tendon lesion may be difficult on magnetic resonance imaging, as well as during arthroscopic inspection. Consequently, the surgical decision of whether to only debride a degenerated tendon or to lateralize the more intact tendon portion may be arbitrary. This study aims to quantify the length of the subscapularis tendon as a sign of partial tendon tearing. METHODS: We retrospectively identified 92 magnetic resonance arthrography studies of suspected rotator cuff lesions obtained 3 months before shoulder arthroscopy. The myotendinous junction was identified, and the subscapularis tendon and muscle lengths were measured. Findings on arthroscopy performed later were used as the diagnostic gold standard for tendon integrity and compared with the magnetic resonance data. RESULTS: Arthroscopy showed an intact subscapularis tendon in 43 patients, tendinopathy in 21 patients, and a partial rupture in 28 patients. The mean subscapularis tendon lengths were 40 mm in cases of intact subscapularis musculotendinous units, 45 mm in cases of tendinopathy, and 53 mm in cases of partial tears, whereas the mean subscapularis muscle lengths were 105 mm, 94 mm, and 95 mm, respectively, in these groups. CONCLUSION: Partial tears of the subscapularis tendon lead to muscle shortening by approximately 10% and elongation of the tendon by approximately 32%, which may be interpreted as muscle retraction and a tendon rupture in continuity. If the subscapularis tendon has an apparent length of greater than 60 mm, the probability of a tear is 98%. Determination of the tendon length may therefore be a useful additional tool to quantify the integrity of the subscapularis tendon and degree of myotendinous retraction.

Secondary latissimus dorsi transfer after failed reverse total shoulder arthroplasty.

BACKGROUND: Combined single-stage reverse total shoulder arthroplasty (RTSA) plus latissimus dorsi transfer (LDT) has been reported to be a reliable treatment for pseudoparalysis of elevation and external rotation caused by irreparable rotator cuff tears. Secondary LDT in patients with pseudoparalysis of external rotation after previous RTSA has not yet been studied. METHODS: Ten patients were treated with LDT at a mean of 27 months (range, 4-134 months) after RTSA. Standard LDT was performed in 4 patients and a LDT plus teres major transfer according to L'Episcopo in 6 patients. All patients had preoperative and postoperative clinical evaluation, including the assessment of the Constant score and the subjective shoulder value. RESULTS: RTSA increased the preoperative mean relative Constant score from 26% (range, 11%-67%) to 51% (range, 20%-100%; P = .05). At a mean of 49 months (range, 23-67 months) after additional LDT, the relative Constant score further increased to 58% (range, 34%-100%; P = .141), remaining significantly superior to the score before RTSA (P = .021). The mean subjective shoulder value was 15% (range, 0%-30%) before and 44% (range, 20%-70%) after RTSA (P = .273) and was 56% (range, 20%-90%) after LDT (P = .686), a significant overall improvement of the state of the shoulder compared with before RTSA (P = .042). Mean active flexion increased from 36° (range, 0°-130°) to 86° (range, 10°-140°) after RTSA (P = .024) and to 109° (range,70°-140°) after LDT (P = 0.017 compared with pre-LDT; P = .011 compared with pre-RTSA). Mean active external rotation decreased from 0° (range, -80° to 50)° to -18° (range, -50°to 10)° after RTSA (P = .079) and was improved to 2° (-40° to 40)° after LDT (P = .24 compared with pre-LDT; P=.865 compared with pre RTSA). CONCLUSION: Secondary LDT significantly improves active mobility in patients with residual dysfunction after RTSA.

H1N1 outbreak in a Swiss military boot camp--observations and suggestions.

QUESTIONS UNDER STUDY: The A(H1N1)pdm09 influenza virus is a highly contagious pathogen which caused the 2009 influenza pandemic. The virus is known to affect mainly younger people and may be a problem in crowded living conditions. The aim of the study was to describe a major A(H1N1)pdm09 outbreak in a Swiss military boot camp and to develop suggestions for similar future situations. METHODS: Retrospective chart analysis of a A(H1N1)pdm09 outbreak between 14 December and 23 December 2010. Symptoms, signs and lab parameters were documented. RESULTS: 105 of 750 male recruits were affected by the outbreak. All nasopharyngeal swabs of 16 patients with high fever were tested positive. Common clinical symptoms included high fever, myalgia and bronchitis with persistent cough and throat aches. Fever progression typically occurred in two peaks within three days. Median length of stay at the infirmary was 3 days (range: 0.5-9 days). CONCLUSION: A(H1N1)pdm09 has become a ubiquitous seasonal virus in the region. Complications were uncommon and non life threatening. In the event of new influenza outbreaks, hygienic and containment measures must be quickly and correctly implemented, in order to avoid an epidemic. This should also be considered in non-military settings like school camps or in retirement homes.

Three-dimensional strain fields in human brain resulting from formalin fixation.

Before investigating human brains post mortem, the first preparation step is often formalin fixation of the brain. As the brain consists of inhomogeneous tissues, the fixation leads to a three-dimensional strain field within the tissue. During the single case MR-based investigation of the brain, first, the starting point with the brain post mortem but still within the cranium, was examined. Then 13 MR data sets were acquired over a fixation period of 70 days and compared to the initial data set. Based on affine registration of the data sets, the global volume shrinkage was found to be 8.1%. By means of a non-rigid registration additional maximal local volume strains of 32% were determined.

Strain fields in histological slices of brain tissue determined by synchrotron radiation-based micro computed tomography.

Accurate knowledge of the morphology of the human brain is required for minimally or non-invasive surgical interventions. On the (sub-)cellular level, brain tissue is generally characterized using optical microscopy, which allows extracting morphological features with a wide spectrum of staining procedures. The preparation of the histological slices, however, often leads to artifacts resulting in imperfect morphological data. In addition, the generation of 3D data is time-consuming. Therefore, we propose synchrotron radiation-based micro computed tomography (SRmicroCT) avoiding preparation artifacts and giving rise to the 3D morphology of features such as gray and white matter on the micrometer level. One can differentiate between white and gray matter without any staining procedure because of different X-ray absorption values. At the photon energy of 10keV, the white matter exhibits the absorption of 5.08 cm(-1), whereby the value for the gray matter corresponds to 5.25 cm(-1). The tomography data allow quantifying the local strains in the histological images using registration algorithms. The deformation of histological slices compared to the SRmicroCT in a 2D-2D registration leads to values of up to 6.3%. Mean deformation values for the Nissl-stained slices are determined to about 1%, whereas the myelin-stained slices yield slightly higher values than 2%.