Acellular Human Dermal Allograft Tuberoplasty Improved the Biomechanics in Mid-Range and Higher Abduction Angles in a Cadaveric Model of Massive Irreparable Rotator Cuff Tears

Purpose

To evaluate the biomechanical effects of acellular human dermal allograft tuberoplasty (AHDAT) in a cadaveric model of an irreparable supraspinatus + anterior one-half infraspinatus (stage III) rotator cuff tear.

Methods

Eight cadaveric shoulders were tested at 20°, 40°, and 60° of glenohumeral abduction (AB) and 0°, 30°, 60°, and 90° of external rotation (ER). Superior humeral translation, acromiohumeral distance, and subacromial contact were quantified for 4 conditions: (1) intact, (2) stage III tear (entire supraspinatus and anterior one-half infraspinatus), (3) single-layer AHDAT, and (4) double-layer AHDAT.

Results

Stage III tear significantly increased superior translation at 20° and 40° AB and all ER angles and at 60° AB/60° ER (P ≤ .045 vs intact). Compared to the stage III tear, the single-layer AHDAT significantly decreased superior translation at 60° AB/60° ER (P = .003), whereas the double-layer AHDAT significantly decreased superior translation at 40° and 60° AB at all ER angles except 60° AB/0° ER (P ≤ .028). The stage III tear significantly decreased acromiohumeral distance at 20° AB (P ≤ .003); both grafts increased acromiohumeral distance to intact levels (P ≥ .055 vs intact). Stage III tear increased subacromial contact pressure at 20° and 40° AB/0° and 30° ER and at 60° AB/30° and 60° ER (P ≤ .034). Both AHDAT groups decreased contact pressure at 40° AB/30° and 60° ER back to intact, whereas the double-layer AHDAT also decreased contact pressure at 20° AB/0° and 60° ER and 60° AB/30° ER (P ≥ .051 vs intact).

Conclusions

Both single- and double-layer grafts for AHDAT improved superior translation, subacromial contact characteristics, and acromiohumeral distance after a stage III rotator cuff tear, with varying effectiveness due to the position-dependent nature of greater tuberosity to acromial contact with abduction.

Clinical Relevance

The best treatment for massive or irreparable rotator cuff tears is a matter of concern. The results of this study will help determine whether an acellular human dermal allograft tuberoplasty is a potential treatment option worthy of further investigation.

Stabilization and Gap Formation of Adjustable Versus Fixed Primary ACL Repair With Internal Brace: An in Vitro Full-Construct Biomechanical Cadaveric Study

Background

A knotless, tensionable primary anterior cruciate ligament (ACL) repair system preloaded with an internal brace has been released. Currently, there is no biomechanical data on the stabilization and gap formation behavior of the adjustable system when compared with fixed repairs in human ACL tissue.

Hypothesis

That knotless adjustable suture repair with an internal brace would provide overall higher construct stability and greater load share on the ACL with less gap formation compared with fixed repair.

Study Design

Controlled laboratory study.

Methods

Human cadaveric knees were utilized for internal braced ACL repair constructs (each group n = 16). Two fixed groups consisting of a single-cinch loop (SCL), cortical button (SCL group), and knotless suture-anchor (anchor group) were compared with an SCL-adjustable loop device (SCL-ALD) group. Testing was performed at 4 different peak loads (50, 150, 250, 350 N) over 4000 cycles at 0.75 Hz including suture repair preconditioning (10 cycles at 0.5 Hz) for SCL-ALD. Specimens were ultimately pulled to failure with a cut internal brace. The final loading situation of the construct and ACL repair with gap formation and ultimate strength were evaluated.

Results

Peak elongation at various peak loads showed a significantly higher (P < .001) stabilization of SCL-ALD when compared with both fixed groups. There was a significantly higher (P < .001) load share of SCL-ALD, especially at lower loads (48% of 50 N), and the gap formation remained restricted up to 250 N. With only a little load share on the fixed constructs (<6%) at lower loads (50, 150 N), gap formation in these groups started at a load of 150 N, leading to significantly higher gaps (P < .001). The ultimate failure load for SCL-ALD and anchor groups was significantly increased (P < .001) as compared with SCL. The stiffness of SCL-ALD (62.9 ± 10.6 N/mm) was significantly increased (P < .001).

Conclusion

Internal braced knotless adjustable fixation for ACL repair with preconditioning of the suture repaired ligament increased the overall stabilization with higher load share on the ACL and restricted gap formation (<0.5 mm up to 350 N) compared with fixed suture repair. All internal braced repairs restored stability according to native ACL function.

Clinical Relevance

Adjustable ACL repair improved the mechanical characteristics and reduced gap formation, but the overall clinical significance on healing remains unclear.

Suture Tape Augmentation of Screw Fixation Reduces Fragment Migration in Tibial Tubercle Osteotomy: A Biomechanical Study

Background:

Tibial tubercle osteotomy (TTO) is a complex surgical procedure with a significant risk of complications, which include nonunion and tibial fracture.

Purpose:

To determine whether an additional suture tape augmentation can provide better biomechanical stability compared with standard screw fixation.

Study Design:

Controlled laboratory study.

Methods:

Five matched pairs of human cadaveric knees were divided into 2 groups: the first group underwent standard TTO fixation with 2 parallel screws (standard group). The second group underwent a novel fixation technique, in which a nonabsorbable suture tape (FiberTape) in a figure-of-8 construct was added to the standard screw fixation for extra stabilization in the inferior-superior direction (augmented group). The specimens were biomechanically tested using a multistep cyclic loading protocol from 400 N up to 800 N to simulate the rehabilitation process. Tubercular fragment migration of >50% of the initial distalization length was defined as clinical failure. A pull-to-failure test was applied to the specimens that survived cyclic loading. Tubercular fragment displacement during cyclic loading and pull-to-failure force were recorded and compared between the 2 groups.

Results:

Two specimens of the standard group exhibited clinical failure during cyclic loading to 400 N. All other specimens survived cyclic loading to 800 N. The augmented group showed less cyclic tubercular fragment displacement after every load level compared with the standard group, with statistically significant differences starting from 500 N (P < .05; power > 0.8). Mean ± standard deviation tubercular fragment displacement at the end of cyclic loading was 2.56 ± 0.82 mm for the augmented group and 5.21 ± 0.51 mm for the standard group. Mean ultimate failure load after the pull-to-failure test was 2475 ± 554 N for the augmented group and 1475 ± 280 N for the standard group.

Conclusion:

The specimens that underwent suture tape augmentation showed less tubercular fragment displacement during cyclic loading and higher ultimate failure forces compared with those that underwent standard screw fixation.

Clinical Relevance:

The augmentation technique could potentially increase the success of a TTO.

Serum protein signatures differentiating autoimmune pancreatitis versus pancreatic cancer

Autoimmune pancreatitis (AIP) is defined by characteristic lymphoplasmacytic infiltrate, ductal strictures and a pancreatic enlargement or mass that can mimic pancreatic cancer (PaCa). The distinction between this benign disease and pancreatic cancer can be challenging. However, an accurate diagnosis may pre-empt the misdiagnosis of cancer, allowing the appropriate medical treatment of AIP and, consequently, decreasing the number of unnecessary pancreatic resections.

Mass spectrometry (MS) and two-dimensional differential gel electrophoresis (2D-DIGE) have been applied to analyse serum protein alterations associated with AIP and PaCa, and to identify protein signatures indicative of the diseases. Patients' sera were immunodepleted from the 20 most prominent serum proteins prior to further 2D-DIGE and image analysis. The identity of the most-discriminatory proteins detected, was performed by MS and ELISAs were applied to confirm their expression. Serum profiling data analysis with 2D-DIGE revealed 39 protein peaks able to discriminate between AIP and PaCa. Proteins were purified and further analysed by MALDI-TOF-MS. Peptide mass fingerprinting led to identification of eleven proteins. Among them apolipoprotein A-I, apolipoprotein A-II, transthyretin, and tetranectin were identified and found as 3.0-, 3.5-, 2-, and 1.6-fold decreased in PaCa sera, respectively, whereas haptoglobin and apolipoprotein E were found to be 3.8- and 1.6-fold elevated in PaCa sera. With the exception of haptoglobin the ELISA results of the identified proteins confirmed the 2D-DIGE image analysis characteristics. Integration of the identified serum proteins as AIP markers may have considerable potential to provide additional information for the diagnosis of AIP to choose the appropriate treatment.