Beat K. Moor

Results after delayed axillary nerve reconstruction with interposition of sural nerve grafts

HYPOTHESIS Satisfactory results after repair of isolated axillary nerve lesions using sural nerve autografts have been reported, but a delay between injury and surgical repair exceeding 6 months was one of the most important negative predictors of functional outcome. From our experience, we hypothesize that good results can be obtained even after a delay exceeding 6 months and we opted in this study to assess the value of delayed axillary nerve reconstruction. MATERIALS AND METHODS We evaluated clinical outcome and donor-site morbidity in 12 patients (mean age, 37; range, 19-66 years) who underwent axillary nerve repair with sural nerve graft with an average 11.25-month a delay between trauma and surgery (range, 8-20 months). Follow-up examination at least 24 months after treatment included assessment of shoulder range of motion, deltoid muscle strength in near full extension, deltoid extension lag, and sensibility. Constant Score, subjective shoulder value, and the Disabilities of Arm, Shoulder and Hand score were also assessed. RESULTS All patients showed an improved deltoid function of at least M3. Postoperative extension lag, as the most specific sign of isolated deltoid function, improved from 57.5 degrees to 14.2 degrees. All stated that they would have identical elective surgery again. Relevant donor-site morbidity was not observed. CONCLUSION Our data indicate that even delayed axillary nerve grafting may lead to satisfactory functional results with a low morbidity and should therefore be done in selected patients.

Radiographic Analysis of Metatarsus Primus Elevatus and Hallux Rigidus

Background: Controversy exists about the role of metatarsus primus elevatus (MPE) in the presence of hallux rigidus. Previous studies could neither confirm nor reject a causative relationship. Measurement of the true elevation of the first metatarsal according to current techniques lack either precision or accuracy or both. The purpose of this study was to assess MPE by means of a new radiographic measurement method and to analyze how the MPE-values differed among hallux rigidus, hallux valgus and control groups. Materials and Methods: A retrospective study was performed of standing AP and lateral radiographs of 295 feet (221 patients; average age 54 years) randomly selected from our databank. According to general radiographic and clinical criteria, 99 were defined as hallux rigidus. Ninety-nine feet had a hallux valgus deformity without severe arthritis. Ninety-seven radiographs with normal MP-I joints and no other forefoot deformity served as a control group. The elevation of the first metatarsal bone in relation to the second metatarsal (MPE), the first metatarsopahlangeal dorsiflexion angle (DFA), the hallux valgus angle (HVA), the intermetatarsal angle (IMA), the interphalangeal angle (IPA) and the degeneration of the first metatarsophalangeal joint were measured. Three independent raters were involved to assess the inter-rater reliability of a new MPE measurement method. For statistic analyses, ANOVA testing was used. Results: MPE was significantly greater in patients with hallux rigidus (+5.2 mm; 95% CI: 4.7 to 5.7) when compared with hallux valgus (+2.8 mm; 95% CI: 2.2 to 3.4) or the control group (+2.6; 95% CI: 2.0–3.2; p < 0.0001). The DFA was found to be significantly lower in the hallux rigidus group (9 degrees; 95% CI: 8 to 10) when compared with those measured in the hallux valgus (14 degrees; 95% CI: 13 to 16) and control groups (11 degrees; 95% CI: 10 to 12; p < 0.0001). There was a no correlation found between MPE and osteoarthritis at MP-I joint (r = 0.35; p < 0.0001). A moderate correlation was found between increasing MPE and decreasing DFA (r = 0.5; p < 0.0001). The inter-rater reliability of the MPE measurement method was found to be accurate and reproducible (r = 0.9; p < 0.0001). Conclusion: Based on the findings in this study, an MPE greater than 5 mm could be considered a predictive factor in the presence of hallux rigidus. However, the mechanism of MPE has yet to be determined. Level of Evidence: III, Case Control Series

Inclination-dependent changes of the critical shoulder angle significantly influence superior glenohumeral joint stability

BACKGROUND The critical shoulder angle combines the acromion index and glenoid inclination and has potential to discriminate between shoulders at risk for rotator cuff tear or osteoarthritis and those that are asymptomatic. However, its biomechanics, and particularly the role of the glenoid inclination, are not yet fully understood. METHODS A shoulder simulator was used to analyze the independent influence of glenoid inclination during abduction from 0 to 60°. Spindle motors transferred tension forces by a cable-pulley on human cadaveric humeri. A six-degree-of-freedom force transducer was mounted directly behind the polyethylene glenoid to measure shear and compressive joint reaction force and calculate the instability ratio (ratio of shear and compressive joint reaction force) with the different force ratios of the deltoid and supraspinatus muscles (2:1 and 1:1). A stepwise change in the inclination by 5° increments allowed simulation of a critical shoulder angle range of 20° to 45°. FINDINGS Tilting the glenoid to cranial (increasing the critical shoulder angle) increases the shear joint reaction force and therefore the instability ratio. A balanced force ratio (1:1) between the deltoid and the supraspinatus allowed larger critical shoulder angles before cranial subluxation occurred than did the deltoid-dominant ratio (2:1). INTERPRETATION Glenoid inclination-dependent changes of the critical shoulder angle have a significant impact on superior glenohumeral joint stability. The increased compensatory activity of the rotator cuff to keep the humeral head centered may lead to mechanical overload and could explain the clinically observed association between large angles and degenerative rotator cuff tears.

Comparison of the critical shoulder angle in radiographs and computed tomography

ObjectiveThe critical shoulder angle (CSA) is an indicator of degenerative shoulder pathologies. CSAs above 35° are associated with degenerative rotator cuff disease, whereas values below 30° are common in osteoarthritis of the glenohumeral joint. Measurements are usually performed on radiographs; however, no data have been reported regarding the reliability of CT scan measurements between different readers or the reproducibility of measurements from radiographs to CT scans. The purpose of our study was to clarify whether CSA measurements on radiographs and CT scans of the same patients show similar values.Materials and methodsCSA measurements of 60 shoulders (59 patients) were performed on radiographs and multiplanar reconstructions of corresponding CT scans. Inter-reader reliability and inter-method correlation were calculated.ResultsThe mean discrepancy between readers was only 0.2° (SD ±1.0°) on radiographs. CT scan measurements showed a mean discrepancy of 0.3° (SD ±1.2°). The inter-reader reliability was 0.993 for radiographs and 0.989 for CT scans. There was a very strong inter-method correlation between the CSA measured on radiographs and CT scans (Spearman’s rho = 0.974). The mean differences between angles on radiographs and CT measurements were −0.05° (SD ±1.2°) and 0.1° (SD ±1.2°), respectively.ConclusionMeasurements of the CSA on anterior-posterior radiographs and CT scans are highly correlated, and inter-modality differences are negligible.

Distal locking of femoral nails: evaluation of a new radiation-independent targeting system.

Objectives: The purpose of this study was to assess the effectiveness of a novel radiation-independent aiming device for distal locking of intramedullary nails in a human cadaver model. Methods: A new targeting system was used in 25 intact human cadaver femora for the distal locking procedure after insertion of an intramedullary nail. The number of successful screw placements and the time needed for this locking procedure were recorded. The accuracy of the aiming process was evaluated by computed tomography. Results: The duration of the distal locking process was 8.0 ± 1.8 minutes (mean ± SD; range, 4–11 minutes). None of the screw placements required fluoroscopic guidance. Computed tomography revealed high accuracy of the locking process. The incidence angle (&agr;) of the locking screws through the distal locking holes of the nail was 86.8° ± 5.0° (mean ± SD; range, 80°–96°). Targeting failed in 1 static locking screw because of a material defect in the drilling sleeve. Conclusions: This cadaver study indicated that an aiming arm–based targeting device is highly reliable and accurate. The promising results suggest that it will help to decrease radiation exposure compared with the traditional “free-hand technique.”

An anatomical investigation of the cervicothoracic ganglion.

Anatomical variability within the autonomic nervous system has long been accepted. This study evaluated the anatomical variability of the cervicothoracic ganglion (CTG) according to its form and, in addition, provided precise measurements between the CTG and the anterior tubercle of the transverse process of the sixth cervical vertebra (C6TP), the first costovertebral articulation, and the vertebral artery. Forty‐two adult cadavers were dissected, 22 male and 20 females. Five main forms of CTG were documented; spindle (31.9%), dumbbell (23.2%), truncated (21.7%), perforated (14.5%), and inverted‐L (8.7%). The means for length, width, and thickness of the CTG were 18.5 mm, 8.2 mm, and 4.5 mm, respectively. The dimensions were found to be slightly larger in the males than females and on the left sides as compared to the right. The mean shortest distance between the CTGs and the vertebral artery was found to be 2.8 mm, whilst the mean shortest distances to C6TP was 25.7 mm and to the first costovertebral articulation was 1.7 mm. There is great variability in the morphology of the CTG with five common forms consistently seen. The relation to the vertebral artery may influence the form of the ganglion. Two previously undocumented forms are recorded; the truncated which describes the important juxtaposition of the CTG and the vertebral artery and the perforated which describes the piercing of the ganglion itself by the artery. The findings are considered to be of clinical importance to anesthetists, surgeons, neurosurgeons, and anatomists. Clin. Anat. 25:444–451, 2012.

Early Serum Procalcitonin Level after Primary Total Hip Replacement

Background. Procalcitonin (PCT) is a useful surrogate marker for the differentiation of postoperative infection and unspecific inflammatory reaction after surgery. It is known that postoperative course of the PCT serum level varies with type of surgery. No data exists about the postoperative course of serum PCT levels after primary total hip replacement (THR). Purpose. To characterize early postoperative serum PCT levels in uneventful primary THR compared to postoperative levels of different frequently used inflammatory blood parameters. Method. We prospectively investigated 31 patients. Blood samples were taken preoperatively and for 5 days postoperatively. PCT levels were compared with C-reactive protein (CRP), interleukin-6 (IL-6), and blood leucocyte counts (WBC). Results. In uneventful THR PCT levels showed a uniform low-level course with a peak at the second postoperative day. At the fifth day values returned to almost preoperative levels. On contrary, CRP levels remained high during the entire observational period. Only IL-6 levels showed a peak at postoperative day one with a quick and uniform return to preoperative levels. Conclusion. Similar to observations in cardiothoracic, intestinal, and neural surgeries, postoperative course of PCT after primary THR showed a uniform low-level course with a peak at the second postoperative day but below expected levels in systemic infections.

Cross-Sectional Area of the Rotator Cuff Muscles in MRI - Is there Evidence for a Biomechanical Balanced Shoulder?

Objective To provide in-vivo evidence for the common biomechanical concept of transverse and craniocaudal force couples in the shoulder that are yielded by both the rotator cuff muscles (RCM) and the deltoid and to quantitatively evaluate and correlate the cross-sectional areas (CSA) of the corresponding RCM as a surrogate marker for muscle strength using MRI. Materials and Methods Fifty patients (mean age, 36 years; age range, 18–57 years; 41 male, 9 female) without rotator cuff tears were included in this retrospective study. Data were assessed by two readers. The CSA (mm2) of all rotator cuff muscles was measured on parasagittal T1-weighted FSE sequence at two different positions (at the established “y-position” and at a more medial slice in the presumably maximal CSA for each muscle, i.e., the “set position”). The CSA of the deltoid was measured on axial intermediate-weighted FSE sequences at three positions. CSA measurements were obtained using 1.5 Tesla MR-arthrographic shoulder. Pearson’s correlation for the corresponding CSA of the force couple as well as was the intraclass correlation coefficient for the inter- and intra-reader agreement was calculated. Results The mean CSA was 770 mm2 (±167) and 841 mm2 (±191) for the supraspinatus (in the y- and set-positions, respectively) and 984 mm2 (±241) and 1568 mm2 (±338) for the infraspinatus. The mean CSA was 446 mm2 (±129) and 438 mm2 (±128) for the teres minor (in the y- and set-positions, respectively) and 1953 mm2 (±553) and 2343 mm2 (±587) for the subscapularis. The three measurements of the deltoid revealed a CSA of 3063 mm2 (±839) for the upper edge, 3829 mm2 (±836) for the lower edge and 4069 mm2 (±937) for the middle of the glenoid. At the set position Pearson’s correlation of the transverse force couple (subscapularis/infraspinatus) showed a moderate positive correlation of r = 0.583 (p<0.0001) and a strong correlation when the CSA of the teres minor was added to the infraspinatus CSA (r = 0.665, p = 0.0008) and a strong positive correlation of the craniocaudal force couple (supraspinatus/deltoid) that ranged from r = 0.565–0.698 (p<0.0001). Inter-reader agreement (ranged from 0.841 to 0.997, p = 0.0007) and intra-reader agreement were excellent (ranged from 0.863 to 0.999, p = 0.0006). Conclusion The significant correlation of the CSA of the RCM that form the transverse (subscapularis/infraspinatus-teres minor) and craniocaudal (supraspinatus/deltoid) force couple measured by MR-arthrography supports the biomechanical concept of a dynamically balanced shoulder in patients with an intact rotator cuff.

Optimal Lateral Row Anchor Positioning in Posterior-Superior Transosseous Equivalent Rotator Cuff Repair: A Micro-Computed Tomography Study.

Background: The optimal placement of suture anchors in transosseous-equivalent (TOE) double-row rotator cuff repair remains controversial. Purpose: A 3-dimensional (3D) high-resolution micro–computed tomography (micro-CT) histomorphometric analysis of cadaveric proximal humeral greater tuberosities (GTs) was performed to guide optimal positioning of lateral row anchors in posterior-superior (infraspinatus and supraspinatus) TOE rotator cuff repair. Study Design: Descriptive laboratory study. Methods: Thirteen fresh-frozen human cadaveric proximal humeri underwent micro-CT analysis. The histomorphometric parameters analyzed in the standardized volumes of interest included cortical thickness, bone volume, and trabecular properties. Results: Analysis of the cortical thickness of the lateral rows demonstrated that the entire inferior-most lateral row, 15 to 21 mm from the summit of the GT, had the thickest cortical bone (mean, 0.79 mm; P = .0001), with the anterior-most part of the GT, 15 to 21 mm below its summit, having the greatest cortical thickness of 1.02 mm (P = .008). There was a significantly greater bone volume (BV; posterior, 74.5 ± 27.4 mm3; middle, 55.8 ± 24.9 mm3; anterior, 56.9 ± 20.7 mm3; P = .001) and BV as a percentage of total tissue volume (BV/TV; posterior, 7.3% ± 2.7%, middle, 5.5% ± 2.4%; anterior, 5.6% ± 2.0%; P = .001) in the posterior third of the GT than in intermediate or anterior thirds. In terms of both BV and BV/TV, the juxta-articular medial row had the greatest value (BV, 87.3 ± 25.1 mm3; BV/TV, 8.6% ± 2.5%; P = .0001 for both) followed by the inferior-most lateral row 15 to 21 mm from the summit of the GT (BV, 62.0 ± 22.7 mm3; BV/TV, 6.1% ± 2.2%; P = .0001 for both). The juxta-articular medial row had the greatest value for both trabecular number (0.3 ± 0.06 mm–1; P = .0001) and thickness (0.3 ± 0.08 μm; P = .0001) with the lowest degree of trabecular separation (1.3 ± 0.4 μm; P = .0001). The structure model index (SMI) has been shown to strongly correlate with bone strength, and this was greatest at the inferior-most lateral row 15 to 21 mm from the summit of the GT (2.9 ± 0.9; P = .0001). Conclusion: The inferior-most lateral row, 15 to 21 mm from the tip of the GT, has good bone stock, the greatest cortical thickness, and the best SMI for lateral row anchor placement. The anterior-most part of the GT 15 to 21 mm below its summit had the greatest cortical thickness of all zones. The posterior third of the GT also has good bone stock parameters, second only to the medial row. The best site for lateral row cortical anchor placement is 15 to 21 mm below the summit of the GT. Clinical Relevance: Optimal lateral anchor positioning is 15 to 21 mm below the summit of the greater tuberosity in TOE.

A pedicled bone graft from the acromion: an anatomical investigation regarding surgical feasibility

OBJECTIVE To investigate the technical feasibility of harvesting a vascularized bone graft from the acromion pedicled on the acromial branch. BACKGROUND Complex fractures of the proximal humerus may result in partial or total avascular necrosis of the head fragment. Treatment of avascular necrosis of the humeral head is dependent upon the stage of disease as well as the dimension and location of necrosis. In general, the outcome is poor and complete restoration of the shoulder function is rarely attained. Contrary to osteonecrosis of carpal bones (where vascularized bone grafts have been routinely carried out for decades), reports of analogous procedures at the humeral head are anecdotal. METHODS Based on selective post-mortem computer-tomographic angiography of 5 and the dissection of 30 embalmed human cadaver shoulders, we describe the anatomy of the acromial branch of the thoracoacromial trunk. The main focus was the constancy of its anatomical course, its dimensions and potential use as a nutrient vessel for a pedicled bone graft from the acromion. RESULTS The course of the acromial branch revealed a constant topographic relationship to anatomical landmarks. Its terminal branches reliably supplied the anterior part of the acromion. The vascularized bone graft could be sufficiently mobilized to allow tension-free transfer to the humeral head as well as to the lateral two-thirds of the clavicle. CONCLUSION We demonstrated the feasibility of vascularized bone graft harvesting from the acromion. This technique could be a joint-preserving procedure for osteonecrosis of the humeral head or may assist in the revision of a clavicular pseudoarthrosis.