TST36 stapling for rectocele and hemorrhoidal prolapse - early results of the prospective German multicenter study.

Introduction: The aim of the study was to evaluate the safety and feasibility of stapled transanal procedures performed by a 36 mm stapling device, the so-called TST36 stapler. Methods: From September 2013 to June 2014 a prospective observational study was carried out by 8 proctology centers in Germany. The Cleveland Clinic Incontinence Score (CCIS) for incontinence and the Altomare ODS score were determined preoperatively. Follow-up examinations were performed after 14 days, one month and 6 months, at this time both scores were reevaluated. Results: 110 consecutive patients (71 women, 39 men) with a mean age of 59.7 years (±13.8 years) were included in the study. The eight participating institutes entered 3 to 31 patients each into the study. The indication for surgery was an advanced hemorrhoidal disease in 55 patients and ODS with rectal intussusception or rectocele in 55 patients. Mechanical problems with stapler introduction occurred in 22 cases (20%) and a partial stapleline dehiscence in 4 cases (3.6%). Additional stitches for bleeding from stapleline were necessary in 86 patients (78.2%). Reintervention was necessary for bleeding 7 times (6.3%). Severe complications during follow-up were stapleline dehiscence in one case and recurrent hemorrhoidal prolapse in 5 cases (4.5%). Altomare ODS score and CCIS improved significantly after surgery. Conclusions: Despite a notable complication rate during surgery and the postoperative period, the TST36 can be considered as an effective tool for low rectal stapling for anorectal prolapse causing hemorrhoids or obstructed defecation.

A comparison of compressive force generation by plating and intramedullary nailing techniques in a transverse diaphyseal humerus fracture model.

BACKGROUND: The null hypothesis to be tested in this study is that the compression forces generated with a novel compressible intramedullary nail are not different from compression plating techniques. METHODS: A custom sensor was used to measure the compressive force at a transverse midshaft humeral sawbone osteotomy (OTA 12-A3.2) in four groups. The groups included: standard compression plating using a limited contact dynamic compression plate (LCDC) with eccentric screw placement (ED-LCDC), compression plating using an LCDC plate with an articulated tensioner and eccentric compression screw (AT-LCDC), locked humeral nail compressed using the manufacturer's long stainless steel screwdriver (T2-IMN), and locked humeral nail compressed using a short stainless steel AO screwdriver (SF-IMN). From continuous measurements recorded during osteotomy compression, the maximum force (CMax) and force at 60 seconds after the peak measurement (CMax +60) were analyzed. RESULTS: The mean CMax was 2043 N for SF-IMN, 1109 N for AT-LCDC, 799 N for T2-IMN, and 365 N for ED-LCDC. Mean CMax +60 was 1648 N for SF-IMN, 944 N for AT-LCDC, 650 N for T2-IMN, and 319 N for ED-LCDC. The difference in both CMax and CMax +60 was statistically significant between all groups (p < 0.002). CONCLUSION: A new humeral nail can generate higher compression than plating using eccentric drill holes or the articulated tensioner when used with a short stainless steel screwdriver shaft. Clinical studies are needed to analyze whether this compression could improve the union rate of humeral fractures and nonunions beyond those of standard nails.

Can a new behaviorally oriented training process to improve lifting technique prevent occupationally related back injuries due to lifting?

STUDY DESIGN: A prospective randomized control trial. OBJECTIVE: To determine the degree to which a new behavior-based lift training program (LiftTrainer; Ascension Technology, Burlington, VT) could reduce the incidence of low back disorder in distribution center jobs that require repetitive lifting. SUMMARY OF BACKGROUND DATA: Most studies show programs aimed at training lifting techniques to be ineffective in preventing low back disorders, which may be due to their conceptual rather than behavioral learning approach. METHODS: A total of 2144 employees in 19 distribution centers were randomized into either the LiftTrainer program or a video control group. In the LiftTrainer program, participants were individually trained in up to 5, 30-minute sessions while instrumented with motion capture sensors to quantify the L5/S1 moments. Twelve months following the initial training, injury data were obtained from company records. RESULTS: Survival analyses (Kaplan-Meier) indicated that there was no difference in injury rates between the 2 training groups. Likewise, there was no difference in the turnover rates. However, those with a low (<30 Nm) average twisting moment at the end of the first session experienced a significantly (P < 0.005) lower rate of low back disorder than controls. CONCLUSIONS: While overall the LiftTrainer program was not effective, those with twisting moments below 30 Nm reported fewer injuries, suggesting a shift in focus for "safe" lifting programs.

Effect of lateral meniscus allograft on shoulder articular contact areas and pressures.

The objective of this study was to determine the effect of a lateral meniscus allograft on the articular contact area and pressures across the glenohumeral joint under compressive loads of 220 N and 440 N. Eight fresh-frozen shoulders were used, and contact areas and pressures were determined with a Tekscan flexible tactile force sensor. Testing conditions included a normal glenohumeral joint and one interposed with a lateral meniscus allograft. Using the Tekscan sensing equipment, we evaluated the total force (in Newtons), contact area (in square millimeters), mean contact pressure (in kilograms per square centimeter), peak force (in Newtons), and peak contact pressure (in kilograms per square centimeter). The interposed lateral meniscus allograft group showed a statistically significant decrease in total force at both 220 N and 440 N, as well as a decrease in contact area for the 220-N testing condition. There were no statistically significant differences between the two groups in contact area at 440 N or in peak forces or peak contact areas for either 220-N or 440-N testing condition. Biomechanically biologic resurfacing with a lateral meniscus allograft of the glenohumeral joint is supported by decreased forces on the glenoid surface.

Three-dimensional in vivo measurement of lumbar spine segmental motion.

STUDY DESIGN: Fifteen asymptomatic volunteers were externally rotated and CT scanned to determine lumbar segmental motion. OBJECTIVES: To measure three-dimensional segmental motion in vivo using a noninvasive measurement technique. SUMMARY OF BACKGROUND DATA: Spinal instability has been implicated as a potential cause of low back pain, especially, axial rotational instability. Typically, flexion-extension lateral radiographs were used to quantify instability, but inaccurately measured translations and inability to capture out-of-plane rotations are limitations. METHODS: Using a custom-calibrated rotation jig, L1-S1 CT reconstructions were created of volunteers in each of 3 positions: supine and left and right rotations of the torso with respect to the hips. Segmental motions were calculated using Euler angles and volume merge methods in three major planes. RESULTS: Segmental motions were small (< 4 degrees or 6 mm) with the greatest motions seen in axial rotation (range, 0.6 degrees to 2.2 degrees ), lateral bending (range, -3.6 degrees to 3.0 degrees ), and frontal translation (-1.2 mm to 5.4 mm). Largest motions were in the levels: L1-L2 to L3-L4. CONCLUSIONS: Complex coupled motions were measured due to external torsion and could be indicative of instability chronic patients with low back pain. The presented data provide baseline segmental motions for future comparisons to symptomatic subjects.

Tibiofemoral contact mechanics after serial medial meniscectomies in the human cadaveric knee.

BACKGROUND: There is no consensus regarding the extent of meniscectomy leading to deleterious effects on tibiofemoral contact mechanics. HYPOTHESIS: The meniscus aids in optimizing tibiofemoral contact mechanics, increasing contact area, and decreasing contact stress. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve fresh-frozen human cadaveric knees each underwent 15 separate testing conditions-5 serial 20-mm posterior medial meniscectomy conditions (intact, 50% radial width, 75% radial width, segmental, and total meniscectomy) at 3 flexion angles (0 degrees , 30 degrees , and 60 degrees )-under an 1800-N axial load. Tekscan sensors were used to measure total force and medial force, contact area, mean contact stress, and peak contact stress. RESULTS: All posterior medial meniscectomy conditions resulted in significantly decreased contact areas and increased mean and peak contact stresses compared with the intact state (P < .05). The changes in contact mechanics after segmental and total posterior medial meniscectomies were not statistically different (P > .05). Incremental changes in contact area and mean contact stress increased as more peripheral portions of the medial meniscus were removed, whereas peak contact stresses exhibited similar incremental changes throughout all meniscectomy conditions. CONCLUSIONS: The meniscus is a crucial load-bearing structure, optimizing contact area and minimizing contact stress. Loss of hoop tension (ie, segmental meniscectomy) is equivalent to total meniscectomy in load-bearing terms. The peripheral portion of the medial meniscus provides a greater contribution to increasing contact areas and decreasing mean contact stresses than does the central portion, whereas peak contact stresses increase proportionally to the amount of meniscus removed. CLINICAL RELEVANCE: Because the degree of meniscectomy leading to clinically significant outcomes is unknown, a prudent strategy is to preserve the greatest amount of meniscus possible.

Enhancement of stability following anterior cervical corpectomy: a biomechanical study.

STUDY DESIGN: An in vitro biomechanical study of various reconstructive techniques following decompression of the spondylotic cervical spine. OBJECTIVE.: To evaluate the biomechanical stability of anterior cervical plate fixation following three strategies of decompression for multilevel cervical spondylosis (three levels) of the cervical spine: three level discectomy, single corpectomy and discectomy, and a two-level corpectomy. SUMMARY OF BACKGROUND DATA: The main goals of surgical treatment for cervical myelopathy include adequate decompression and stabilization while maintaining or restoring cervical lordosis. Cervical decompression is often performed through a corpectomy followed by strut-graft reconstruction. An anterior cervical plate with end-fixation (two points of fixation) is then used to span the construct. The authors propose an alternative to multilevel corpectomy and long-segment end construct plate fixation. Often times, the cervical stenosis is confined to the area of the degenerative discs. As a result, the authors feel that either multilevel discectomy or a corpectomy combined with discectomy followed by segmental plate fixation may provide adequate decompression with increased biomechanical rigidity as compared to cervical plate-constructs with end-fixation only. METHODS: Seven human cadaveric fresh-frozen cervical spines from C1-T1 were utilized. Three-dimensional motion analysis with an optical tracking device was used to determine motion following various reconstruction methods. All seven cervical spines underwent testing in a randomized order. The end construct model consisted of a corpectomy at C4 and C5 with a polymethyl methacrylate strut graft and an anterior cervical PEAK (DePuy-AcroMed) plate. The two segmental constructs also utilized the PEAK plate with one construct undergoing discectomies at C3-C4, C4-C5, and C5-C6 with polymethyl methacrylate interbody grafts and the other segmental construct undergoing a discectomy at C3-C4 and a corpectomy of C5. All specimens underwent a pure moment application of 2 Nm with regards to flexion-extension, lateral bending, and axial rotation. RESULTS.: The three-level discectomy and combined one-level discectomy and corpectomy with segmental fixation was significantly more rigid in flexion-extension and lateral bending than the two-level corpectomy with end-construct plate fixation (P < 0.05). There was no increase in stability during extension between the end construct (two-level corpectomy) reconstruction model and the un-instrumented corpectomy and grafted specimen. No difference was noted between the segmental constructs and the end-construct with regards to axial rotation. CONCLUSIONS: Cervical myelopathy is traditionally treated with a multilevel corpectomy and an end-construct plate fixation spanning the strut graft. A large moment arm is generated at the ends of the construct, potentially leading to plate migration or dislodgment. Often times, adequate decompression can be achieved with either a multilevel discectomy or a combined discectomy and corpectomy with segmental plate fixation. This study clearly demonstrates that segmental plate fixation affords a more biomechanically rigid method of reconstruction with regards to flexion-extension and lateral bending than end-construct plate fixation. The increased rigidity afforded by segmental fixation may significantly decrease the likelihood of plate dislodgement in the setting of anterior instrumentation alone following anterior alone, long segment reconstruction procedures.

Biomechanical comparison of cervical spine reconstructive techniques after a multilevel corpectomy of the cervical spine.

STUDY DESIGN: An in vitro biomechanical study of several reconstructive techniques after a two-level cervical corpectomy. OBJECTIVES: To evaluate, compare, and quantitate the stability of several reconstructive strategies (anterior, posterior, or anterior/posterior with or without instrumentation) after a multilevel cervical corpectomy. SUMMARY OF BACKGROUND DATA: Several clinical and biomechanical studies have questioned the stability of stand-alone long-segment anterior plate fixation after a multilevel (>or=2) corpectomy. The large cantilever forces generated within the stabilized construct, particularly at the caudal screw-bone interface, have led to plate and screw dislodgement and the need for further surgical intervention. The addition of posterior segmental instrumentation has been shown to improve overall stability and decrease local stresses on the anterior fusion construct (graft and plate). MATERIALS AND METHODS: Seven fresh-frozen cadaveric human cervical spines (C1-T1) were harvested. The C1-C2 and C7-T1 vertebral bodies were embedded in poly-methylmethacrylate (PMMA). Three VICON cameras tracked three-dimensional segmental motions at the ends of the fusion construct after a two-level corpectomy and placement of a strut graft with or without instrumentation. Pure moments (flexion/extension, lateral bending, and axial rotation) were applied to the C1 level of each specimen. The motion segments were loaded to a maximum of 2 Nm using dead weights. Testing was first performed on the intact specimens. Then, a two-level corpectomy at the C4 and C5 levels was performed. A PMMA strut graft was then placed into the corpectomy site. Biomechanical testing was then repeated among three different reconstruction techniques: 1) anterior cervical locking plate (PEAK; Depuy-Acromed, Raynham, MA) with dual unicortical screw fixation at C3 and C6; 2) posterior cervical instrumentation (Summit; Depuy-Acromed) using a 3.0-mm rod with segmental lateral mass screw fixation from C3 to C6; and 3) a combined anterior-posterior instrumentation using the anterior PEAK plate and posterior Summit rod system. RESULTS: In all pure moments tested (flexion/extension/lateral bending/axial rotation) the combined anterior-posterior instrumentation reconstruction model and the posterior-only instrumentation model were significantly more rigid than the anterior-only instrumentation model (P < 0.05). Interestingly, no statistically significant difference was noted between the combined anterior plate/posterior instrumentation model and the posterior instrumentation-only model. CONCLUSION: The biomechanical results obtained suggest that posterior segmental instrumentation confers significant stability to a multilevel cervical corpectomy regardless of the presence or absence of anterior instrumentation. In cases in which the stability of a multilevel reconstruction procedure is tenuous, the surgeon should strongly consider the placement of segmental posterior instrumentation to significantly improve the overall stability of the fusion construct.