Biodegradable spacer reduces the subacromial pressure: A biomechanical cadaver study.

BACKGROUND: Failure after rotator cuff repair remains a major clinical problem and could be related to excessive pressures from the acromion. Previous studies with irreparable tears showed good clinical results of tendon healing with arthroscopic insertion of a protective biodegradable spacer balloon between the repaired tendon and the acromion. One hypothesis is that compression pressures on the repaired tendon will be reduced by the spacer. This cadaver study aimed to investigate the effects of this subacromial spacer on compression pressures over a repaired supraspinatus tendon in passive motion. METHODS: Rotator cuff tear and repair were performed in six fresh-frozen cadaveric shoulders, followed by insertion of a biodegradable subacromial spacer. Specimens were tested using a passive shoulder simulator for abduction-adduction, flexion-extension and internal-external rotations. A sensor positioned below the acromion was used to measure compression pressure changes through passive range of motion before and after placement of a subacromial spacer. Peak pressures were measured in adduction-abduction motion, near 90° abduction. FINDINGS: Both the mean and peak pressures in abduction-adduction were significantly reduced after insertion of the subacromial spacer (from mean 121.7 (SD 9.5) MPa to 51.5 (SD 1.2) MPa and from peak 1749.6 (SD 80.7) MPa to 535.1 (SD 27.6) MPa) (P<0.0001). INTERPRETATION: The reduced peak pressures and wider load distributions over the sensor during both passive abduction-adduction and flexion-extension motions suggest that the use of the spacer will lead to reduced wear of the repair in patients, and potentially prevent rotator cuff re-tear after surgical repair.

The biodegradable spacer as a novel treatment modality for massive rotator cuff tears: a prospective study with 5-year follow-up.

BACKGROUND: The management of massive, irreparable rotator cuff tears (RCT) is challenging and associated with high failure rates. There are no current consensus or definitive guidelines concerning the optimal surgical treatment for this devastating condition. This study was designed to confirm the long-term safety and efficacy of the biodegradable inflatable InSpace™ system in patients with massive reparable or irreparable RCTs. METHODS: In this open-label, single arm, prospective study, subjects with massive RCT underwent subacromial implantation with the biodegradable spacer. Follow-up visits were scheduled according to routine clinical practice. Shoulder function was evaluated using Total Constant Score (TCS). RESULTS: Twenty-four patients were treated and assessed. Four patients had partial tears, and in three of them RC repair was performed. These patients were not included in the efficacy analyses. Of the participating subjects who reached the 5-year follow-up, 84.6% of the patients showed a clinically significant improvement of at least 15 points in their score, while 61.54% showed at least 25 points of improvement. Only 10% of the treated patients showed no improvement or worsening in the shoulder score comparing to their baseline. An overall improvement in the total CS commencing at 3 months and sustained by 6 months through to 5 years of follow-up (P < 0.0001) was demonstrated. CONCLUSIONS: We conclude that in this initial cohort, arthroscopic implantation of InSpace™ system represented an effective alternative to the existing arthroscopic procedures in patients with painful massive RCT refractory to conservative management. Further randomized controlled trials comparing the clinical and functional outcomes after implantation of the InSpace™ device are warranted.

Long-term Local and Systemic Safety of Poly(L-lactide-co-epsilon-caprolactone) after Subcutaneous and Intra-articular Implantation in Rats.

The use of biodegradable materials is gaining popularity in medicine, especially in orthopedic applications. However, preclinical evaluation of biodegradable materials can be challenging, since they are located in close contact with host tissues and might be implanted for a long period of time. Evaluation of these compounds requires biodegradability and biocompatibility studies and meticulous pathology examination. We describe 2 preclinical studies performed on Sprague-Dawley rats for 52 weeks, to evaluate clinical pathology, biocompatibility, biodegradability, and systemic toxicity after implantation of 2-layered films or saline-inflated balloon-shaped implants of downsized InSpace™ devices (termed "test device"). The test devices are made from a copolymer of poly-L-lactide-co-∊-caprolactone in a 70:30 ratio, identical to the device used in humans, intended for the treatment of rotator cuff tears. Intra-articular film implantation and subcutaneous implantation of the downsized device showed favorable local and systemic tolerability. Although the implanted materials have no inherent toxic or tumorigenic properties, one animal developed a fibrosarcoma at the implantation site, an event that is associated with a rodent-predilection response where solid materials cause mesenchymal neoplasms. This effect is discussed in the context of biodegradable materials along with a detailed description of expected pathology for biodegradable materials in long-term rodent studies.

Fluoroscopy-guided implantation of subacromial "biodegradable spacer" using local anesthesia in patients with irreparable rotator cuff tear.

Treatment of massive rotator cuff tears can be challenging, especially when tears are considered irreparable or, when repaired, at significant risk of retear. A surgical technique is described using a biodegradable subacromial balloon-shaped spacer (InSpace; Ortho-Space, Caesarea, Israel) that, when implanted between the humeral head and acromion, permits smooth, frictionless gliding, supporting shoulder biomechanics. The specific insertion technique described herein is a simple procedure that can be performed in a day-care or outpatient setting with patients under local anesthesia, thus providing a treatment option for patients with multiple comorbidities complicating or contraindicating surgery, such as reverse arthroplasty under general anesthesia.

Prospective clinical study of a novel biodegradable sub-acromial spacer in treatment of massive irreparable rotator cuff tears.

PURPOSE: The purposes of this prospective non-randomized study were to confirm the feasibility of the biodegradable sub-acromial spacer (InSpace™) implantation in patients with massive irreparable rotator cuff tear and to determine the safety profile and functional results 3 years post-implantation. METHODS: Twenty patients were implanted with the InSpace™ device and assessed up to 3 years of post-implantation. Improvement in shoulder function was assessed using Constant score, while ease of use of the system was recorded by surgeons as were device-related adverse events. RESULTS: Twenty patients were available for assessment. Implantation was performed arthroscopically in all patients, and a range of deployment time was 2-20 min. The mean total Constant score increased from 33.4 to 65.4 points at 3 years. There was an improvement of 6.4 points in subjective pain score which commenced at 1 week post-operatively and was sustained until 3 years of follow-up. Also activities of daily living and motions commenced improvement by 9.4 and 7.7 points, respectively. Improvement in power was only evident at 18 months of follow-up but was sustained at 3 years. CONCLUSIONS: Arthroscopic deployment of a co-polymer biodegradable spacer (balloon) into the sub-acromial space for an irreparable rotator cuff tear was found to be low-risk and simple procedure associated with improvement in shoulder function and low rate of complications. LEVEL OF EVIDENCE: IV; therapeutic case series.

Computer-assisted surgery for dynamic hip screw, using Surgix, a novel intraoperative guiding system.

BACKGROUND: We present Surgix, a new computer-assisted surgery system (CASS). This system uses image analysis technology in order to measure three-dimensional (3D) distances, visualize implant templates and view the guided trajectory on standard fluoroscopy. Our purpose was to compare surgery results and technique with and without the Surgix CASS. METHODS: The study included 61 dynamic hip screw (DHS) procedures. The Surgix system was used in 41 procedures. We compared the number of guide wire insertion trials and the time needed for each trial, the number of X-ray pulses, tip-apex index, nine-quadrant position and shaft-neck angle. RESULTS: The procedures were carried out by experienced users (> or = five operations, using the system) and had a first-trial guide wire insertion success rate of 77.8%, compared to a rate of 10% for the control group (p = 0.001) and fewer insertion trials (1.33 vs. 3.05, respectively; p = 0.001). The mean number of fluoroscopy pulses was 41.5% lower for the experienced group than for the control (17.6 vs. 30.1; p = 0.009). There were no significant differences in tip-apex distance, favourable quadrant screw placement or neck-shaft angle. CONCLUSION: The results of this study demonstrate that the Surgix CASS significantly improves the accuracy of hardware positioning and reduces radiation exposure time, thus enhancing patient outcome.