Philipp N. Streubel

Open Surgical Release for Contractures of the Elbow

Compared with arthroscopic release, open release is more commonly used for the treatment of stiff elbow. Flexion is recovered by releasing posterior tethering soft-tissue structures and by removing anterior impingement between the coronoid and/or radial head and the distal humerus. Extension is improved by releasing anterior soft-tissue tethers and by removing impingement between the olecranon tip and the olecranon fossa. Open elbow release is most commonly performed via ligament-sparing approaches. Ulnar nerve identification and transposition is recommended in the presence of nerve dysfunction or when correction of significant loss of elbow flexion is anticipated. Long-term improvement in flexion and extension can be expected with proper patient selection. Less predictable results are obtained in adolescent patients and in those with underlying traumatic brain injury.

Living nanofiber yarn-based woven biotextiles for tendon tissue engineering using cell tri-culture and mechanical stimulation

Non-woven nanofibrous scaffolds have been developed for tendon graft application by using electrospinning strategies. However, electrospun nanofibrous scaffolds face some obstacles and limitations, including suboptimal scaffold structure, weak tensile and suture-retention strengths, and compact structure for cell infiltration. In this work, a novel nanofibrous, woven biotextile, fabricated based on electrospun nanofiber yarns, was implemented as a tissue engineered tendon scaffold. Based on our modified electrospinning setup, polycaprolactone (PCL) nanofiber yarns were fabricated with reproducible quality, and were further processed into plain-weaving fabrics interlaced with polylactic acid (PLA) multifilaments. Nonwoven nanofibrous PCL meshes with random or aligned fiber structures were generated using typical electrospinning as comparative counterparts. The woven fabrics contained 3D aligned microstructures with significantly larger pore size and obviously enhanced tensile mechanical properties than their nonwoven counterparts. The biological results revealed that cell proliferation and infiltration, along with the expression of tendon-specific genes by human adipose derived mesenchymal stem cells (HADMSC) and human tenocytes (HT), were significantly enhanced on the woven fabrics compared with those on randomly-oriented or aligned nanofiber meshes. Co-cultures of HADMSC with HT or human umbilical vein endothelial cells (HUVEC) on woven fabrics significantly upregulated the functional expression of most tenogenic markers. HADMSC/HT/HUVEC tri-culture on woven fabrics showed the highest upregulation of most tendon-associated markers than all the other mono- and co-culture groups. Furthermore, we conditioned the tri-cultured constructs with dynamic conditioning and demonstrated that dynamic stretch promoted total collagen secretion and tenogenic differentiation. Our nanofiber yarn-based biotextiles have significant potential to be used as engineered scaffolds to synergize the multiple cell interaction and mechanical stimulation for promoting tendon regeneration. STATEMENT OF SIGNIFICANCE Tendon grafts are essential for the treatment of various tendon-related conditions due to the inherently poor healing capacity of native tendon tissues. In this study, we combined electrospun nanofiber yarns with textile manufacturing strategies to fabricate nanofibrous woven biotextiles with hierarchical features, aligned fibrous topography, and sufficient mechanical properties as tendon tissue engineered scaffolds. Comparing to traditional electrospun random or aligned meshes, our novel nanofibrous woven fabrics possess strong tensile and suture-retention strengths and larger pore size. We also demonstrated that the incorporation of tendon cells and vascular cells promoted the tenogenic differentiation of the engineered tendon constructs, especially under dynamic stretch. This study not only presents a novel tissue engineered tendon scaffold fabrication technique but also provides a useful strategy to promote tendon differentiation and regeneration.

Revision of failed humeral head resurfacing arthroplasty

Purpose: The purpose of this study is to assess the outcomes of a consecutive series of patients who underwent revision surgery after humeral head resurfacing (HHR). Our joint registry was queried for all patients who underwent revision arthroplasty for failed HHR at our institution from 2005 to 2010. Eleven consecutive patients (average age 54 years; range 38-69 years) that underwent revision of 11 resurfacing arthroplasties were identified. The primary indication for resurfacing had been osteoarthritis in six, glenoid dysplasia in two, a chondral lesion in two, and postinstability arthropathy in one patient. The indication for revision was pain in 10 and infection in one patient. Seven patients had undergone an average of 1.9 surgeries prior to resurfacing (range 1-3). Materials and Methods: All patients were revised to stemmed arthroplasties, including one hemiarthroplasty, two reverse, and eight anatomic total shoulder arthroplasties at a mean 33 months after primary resurfacing (range 10-131 months). A deltopectoral approach was used in seven patients; four patients required an anteromedial approach due to severe scarring. Subscapularis attenuation was found in four cases, two of which required reverse total shoulder arthroplasty. Bone grafting was required in one glenoid and three humeri. Results: At a mean follow-up of 3.5 years (range 1.6-6.9 years), modified Neer score was rated as satisfactory in five patients and unsatisfactory in six. Abduction and external rotation improved from 73° to 88° (P = 0.32) and from 23° to 32° (P = 0.28) respectively. Reoperation was required in two patients, including one hematoma and one revision for instability. Conclusion: Outcomes of revision of HHR arthroplasty in this cohort did not improve upon those reported for revision of stemmed humeral implants. A comparative study would be required to allow for definitive conclusions to be made.

Effect of scaffold morphology and cell co-culture on tenogenic differentiation of HADMSC on centrifugal melt electrospun poly (L‑lactic acid) fibrous meshes

Engineered tendon grafts offer a promising alternative for grafting during the reconstruction of complex tendon tears. The tissue-engineered tendon substitutes have the advantage of increased biosafety and the option to customize their biochemical and biophysical properties to promote tendon regeneration. In this study, we developed a novel centrifugal melt electrospinning (CME) technique, with the goal of optimizing the fabrication parameters to generate fibrous scaffolds for tendon tissue engineering. The effects of CME processing parameters, including rotational speed, voltage, and temperature, on fiber properties (i.e. orientation, mean diameter, and productivity) were systematically investigated. By using this solvent-free and environmentally friendly method, we fabricated both random and aligned poly (L-lactic acid) (PLLA) fibrous scaffolds with controllable mesh thickness. We also investigated and compared their morphology, surface hydrophilicity, and mechanical properties. We seeded human adipose derived mesenchymal stem cells (HADMSC) on various PLLA fibrous scaffolds and conditioned the constructs in tenogenic differentiation medium for up to 21 days, to investigate the effects of fiber alignment and scaffold thickness on cell behavior. Aligned fibrous scaffolds induced cell elongation and orientation through a contact guidance phenomenon and promoted HADMSC proliferation and differentiation towards tenocytes. At the early stage, thinner scaffolds were beneficial for HADMSC proliferation, but the scaffold thickness had no significant effects on cell proliferation for longer-term cell culture. We further co-seeded HADMSC and human umbilical vein endothelial cells (HUVEC) on aligned PLLA fibrous mats and determined how the vascularization affected HADMSC tenogenesis. We found that co-cultured HADMSC-HUVEC expressed more tendon-related markers on the aligned fibrous scaffold. The co-culture systems promoted in vitro HADMSC differentiation towards tenocytes. These aligned fibrous scaffolds fabricated by CME technique could potentially be utilized to repair and regenerate tendon defects and injuries with cell co-culture and controlled vascularization.

Infection in total elbow arthroplasty with stable components: outcomes of a staged surgical protocol with retention of the components

AIMS We describe the use of a protocol of irrigation and debridement (I&D) with retention of the implant for the treatment of periprosthetic infection of a total elbow arthroplasty (TEA). This may be an attractive alternative to staged re-implantation. PATIENTS AND METHODS Between 1990 and 2010, 23 consecutive patients were treated in this way. Three were lost to follow-up leaving 20 patients (21 TEAs) in the study. There were six men and 14 women. Their mean age was 58 years (23 to 76). The protocol involved: component unlinking, irrigation and debridement (I&D), and the introduction of antibiotic laden cement beads; organism-specific intravenous antibiotics; repeat I&D and re-linkage of the implant if appropriate; long-term oral antibiotic therapy. RESULTS The mean follow-up was 7.1 years (2 to 16). The infecting micro-organisms were Staphylococcus aureus in nine, coagulase-negative Staphylococcus in 13, Corynebacterium in three and other in six cases. Re-operations included three repeat staged I&Ds, two repeat superficial I&Ds and one fasciocutaneous forearm flap. One patient required removal of the implant due to persistent infection. All except three patients rated their pain as absent or mild. Outcome was rated as good or excellent in 15 patients (mean Mayo Elbow Performance Score 78 points, (5 to 100) with a mean flexion-extension arc of 103° (40° to 150°)). CONCLUSION A staged protocol can be successful in retaining stable components of an infected TEA. Function of the elbow may compare unfavourably to that after an uncomplicated TEA. Cite this article: Bone Joint J 2016;98-B:976-83.

Total Elbow Arthroplasty for Distal Humeral Fractures: A Ten-Year-Minimum Follow-up Study.

Background: Total elbow arthroplasty is commonly considered for elderly patients with comminuted distal humeral fractures. Satisfactory short-term outcomes have been reported, but long-term outcomes are unknown. Our purpose was to assess the long-term outcomes of total elbow arthroplasty after distal humeral fracture and to determine differences between elbows with or without inflammatory arthritis at the time of fracture. Methods: Forty-four total elbow arthroplasties were performed after distal humeral fracture; those patients were followed for a minimum of 10 years and were evaluated with regard to pain, motion, Mayo Elbow Performance Scores, complications, and reoperations. The outcomes in elbows with and without inflammatory arthritis were compared. Kaplan-Meier survivorship analysis was performed. Results: Total elbow arthroplasty provided good pain relief and motion; the mean visual analog scale for pain was 0.6, the mean flexion was 123°, and the mean loss of extension was 24°. The mean Mayo Elbow Performance Score was 90.5 points, with 3 patients scoring <75 points. Five elbows (11%) developed deep infection, treated surgically with component retention (3 acute) or resection (2 chronic). Implant revision or resection was performed in 8 elbows (18%): 3 for infections (1 reimplantation and 2 resections), 3 for ulnar loosening (associated with periprosthetic fracture in 1), and 2 for ulnar component fractures. Additional periprosthetic fractures were observed in 5 elbows. The survival rates for elbows with rheumatoid arthritis were 85% at 5 years and 76% at 10 years, and the survival rates for elbows without rheumatoid arthritis were 92% at both 5 and 10 years. The most relevant risk factor for revision was male sex (hazard ratio, 12.6 [95% confidence interval, 1.7 to 93.6]). Conclusions: Selective use of total elbow arthroplasty to treat fractures of the distal part of the humerus for infirm, less active older patients and patients with inflammatory arthritis has acceptable longevity in surviving patients, but at the cost of a number of major complications. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Change in the Distance From the Axillary Nerve to the Glenohumeral Joint With Shoulder External Rotation or Abduction Position

Background: This study investigated whether axillary nerve (AN) distance to the inferior border of the humeral head and inferior glenoid would change while placing the glenohumeral joint in different degrees of external rotation and abduction. Methods: A standard deltopectoral approach was performed on 10 fresh-frozen cadaveric specimens. The distance between AN and the inferior border of the humeral head and inferior glenoid while placing the shoulder in 0°, 45°, and 90° of external rotation or abduction was measured. Continuous variables for changes in AN position were compared with paired 2-tailed Student t test. Results: The mean distance between the AN and the humeral head with the shoulder in 0°, 45°, and 90° of external rotation and 0° of abduction was 13.77 mm (SD 4.31), 13.99 mm (SD 4.12), and 16.28 mm (SD 5.40), respectively. The mean distance between the AN and glenoid with the shoulder in 0°, 45°, and 90° of external rotation was 16.33 mm (SD 3.60), 15.60 mm (SD 4.19), and 16.43 (SD 5.35), respectively. The mean distance between the AN and the humeral head with the shoulder in 0°, 45°, and 90° of abduction and 0° of external rotation was 13.76 mm (SD 4.31), 10.68 mm (SD 4.19), and 3.81 mm (SD 3.08), respectively. The mean distance between the AN and glenoid with the shoulder in 0°, 45°, and 90° of abduction was 16.33 mm (SD 3.60), 17.66 mm (SD 5.80), and 12.44 mm (SD 5.57), respectively. Conclusions: The AN position relative to the inferior aspect of the glenohumeral joint does not significantly change despite position of external rotation. Increasing shoulder abduction over 45° decreases the distance from the glenohumeral joint to the AN and should be avoided.