Graft failure and revision rate after ACL repair with dynamic intraligamentary stabilization. One-year results of a prospective case series of 155 patients.

PURPOSE: The aim of this study was to assess graft failure, revision rate, and functional outcomes after treatment of acute ACL rupture with dynamic intraligamentary stabilization (DIS) Ligamys device one year post surgery. Additionally, differences in functional outcome between patients with and without anteroposterior laxity were assessed. It was hypothesized that the failure rate of DIS was non-inferior to that of previously reported ACL reconstruction (10%). METHODS: In this prospectively designed multicenter study, including patients with an acute ACL rupture, DIS was performed within 21 days after rupture. Primary outcome was failure of the graft at 1 year post surgery, defined as 1) re-rupture of the graft, 2) revision of DIS, or 3) a > 3 mm side-to-side difference in anterior tibial translation compared to the non-operated knee (∆ATT), measured by the KT1000 device. Additional analysis was performed using a 5 mm threshold. The subjective International Knee Documentation Committee Score (IKDC) and Numerical Rating Scales (NRS) for pain and confidence were used to evaluate functional outcome. RESULTS: A total of 155 patients were included with a mean age at surgery of 27.8 years (SD 9.4). The mean interval from rupture to DIS was 16.4 days (SD 5.2). At a median follow-up of 13 months (IQR 12-18) the failure rate of the graft was 30.2% (95%CI:22.0-39.4); 11 patients (7%) required secondary reconstructive surgery and of the 105 patients who attended ATT measurement, 24 patients (23%) had an ∆ATT > 3 mm. Secondary analysis, based on a 5 mm threshold, revealed a failure rate of 22.4% (95%CI: 15.2; 31.1). A total of 39 patients (25%) reported at least one complication, comprising mainly arthrofibrosis, traumatic re-rupture and pain. In these patients, removal of the monoblock was performed in 21 cases (13.5%). At follow-up no significant differences in functional outcomes between patients with ∆ATT > 3 mm and stable ATT were observed. CONCLUSION: This prospective multicenter study found a high failure rate at one year follow-up of 30% (7% revision surgery and 23% > 3 mm side-to-side difference in anterior tibial translation) in patients treated by primary repair of the ACL with DIS, and did therefore not demonstrate non-inferiority to ACL reconstruction. For patients who did not require secondary reconstructive surgery, this study found good functional outcomes, also in case of persistent anteroposterior knee laxity (∆ATT > 3 mm). LEVEL OF EVIDENCE: Level IV.

Risk factors for postoperative pain in the first three weeks after arthroscopic or open shoulder surgery.

INTRODUCTION: Shoulder surgery is a painful procedure. Adequate postoperative pain control increases patient satisfaction. The objectives of this study were to investigate postoperative pain development in shoulder surgery and to assess risk factors for high postoperative pain. HYPOTHESIS: Patients who undergo rotator cuff repair are more painful than patients who undergo different kinds of shoulder surgery. MATERIAL AND METHODS: Four hundred and sixty five patients who underwent shoulder surgery were included in this retrospective cohort study. A linear mixed model analysis was used to compare NRS (Numeric Rating Scale) for pain between different kinds of shoulder surgery in the first three weeks postoperatively. To assess risk factors for high postoperative pain odds ratios were calculated. RESULTS: Pain development in the first 3 weeks differed between procedures with rotator cuff repair being the most painful procedure. Risk factors for high postoperative pain were female sex and subacromial decompression with distal clavicle resection. DISCUSSION: Patients who undergo rotator cuff repair are indeed more painful than patients who undergo different kinds of shoulder surgery. With identifying these differences in pain development and the risk factors for high postoperative pain after shoulder surgery, we can optimize postoperative pain treatment. However, further research is needed to support these results. LEVEL OF EVIDENCE: IV, retrospective cohort study.

In vivo matrix production by bone marrow stromal cells seeded on PLGA scaffolds for ligament tissue engineering.

Ligament tissue engineering based on cell-seeded biomechanically functional constructs is a commonly studied strategy toward native anterior cruciate ligament replacement. Little is known about the survival and differentiation of the seeded cells after the transplantation. We applied retroviral genetic marking to trace implanted cells and studied their differentiation by species-specific immunolabeling of the extracellular matrix produced. Goat bone marrow stromal cells were transduced with a MoMuLV-based vector encoding the DeltaLNGFR gene. Transduced cells were seeded onto poly(lactic-co-glycolic acid) (PLGA) fibers and implanted subcutaneously into nude mice and left for various periods up to 6 weeks. Immunohistochemistry for LNGFR expression showed survival of the seeded cells after transplantation for up to 6 weeks. Immunohistochemistry for collagen type I and III showed the production of fibrous tissue inside the scaffolds. Moreover, using a goat-specific anti-collagen type III, donor-derived matrix could be demonstrated. We conclude that bone marrow stromal cells survived in vivo and at least partially differentiated after implantation.

The effect of timing of mechanical stimulation on proliferation and differentiation of goat bone marrow stem cells cultured on braided PLGA scaffolds.

Bone marrow stromal cells (BMSCs) have been shown to proliferate and produce matrix when seeded onto braided poly(L-lactide/glycolide) acid (PLGA) scaffolds. Mechanical stimulation may be applied to stimulate tissue formation during ligament tissue engineering. This study describes for the first time the effect of constant load on BMSCs seeded onto a braided PLGA scaffold. The seeded scaffolds were subjected to four different loading regimes: Scaffolds were unloaded, loaded during seeding, immediately after seeding, or 2 days after seeding. During the first 5 days, changing the mechanical environment seemed to inhibit proliferation, because cells on scaffolds loaded immediately after seeding or after a 2-day delay, contained fewer cells than on unloaded scaffolds or scaffolds loaded during seeding (p<0.01 for scaffolds loaded after 2 days). During this period, differentiation increased with the period of load applied. After day 5, differences in cell content and collagen production leveled off. After day 11, cell number decreased, whereas collagen production continued to increase. Cell number and differentiation at day 23 were independent of the timing of the mechanical stimulation applied. In conclusion, static load applied to BMSCs cultured on PLGA scaffolds allows for proliferation and differentiation, with loading during seeding yielding the most rapid response. Future research should be aimed at elucidating the biomechanical and biochemical characteristics of tissue formed by BMSCs on PLGA under mechanical stimulation.