Nonaugmented Group Research Articles

Does Allograft Augmentation of Small-Diameter Hamstring Autograft ACL Grafts Reduce the Incidence of Graft Retear?

Background: Small-diameter hamstring tendons are frequently encountered during anterior cruciate ligament (ACL) reconstructions in patients with short stature or those who are skeletally immature. The role of augmenting these small-diameter autografts with allograft is unclear. Purpose: To assess clinical outcomes and failure rates in adolescent patients with small hamstring tendon autografts (<7 mm) that were either augmented with soft tissue allograft or accepted “as is” and not augmented. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective chart review of all primary ACL reconstructions performed with hamstring autografts identified 385 patients, of whom 50 (13%) had a quadrupled (semitendinosus-gracilis) graft size less than 7 mm. Patients were grouped based on the surgeon’s preference either to augment these grafts with allograft (augmented group; n = 26) or to accept the smaller autograft (nonaugmented group; n = 24). Preoperative demographic, injury, and intraoperative data were documented. All patients were contacted to obtain information about outcome scores, subsequent procedures, and complications. Forty patients (20 in each group) were available for 2-year follow-up. Results: The mean age of the entire cohort was 15.7 years (range, 12-18 years), and 38% were male. No between-group differences were found with respect to any of the preoperative or intraoperative variables except extremity side. The mean graft size for the augmented group was 8.9 mm and for the nonaugmented group was 6.4 mm. At a mean follow-up of 3 years, 6 (30%) of the patients in the augmented group had a graft failure, whereas only 1 (5%) in the nonaugmented group had a failure (P = .04). Five of the 6 augmented failures occurred within 1 year of surgery, whereas the single failure in the nonaugmented group occurred 2.7years postoperatively. No differences were noted in the reported outcomes between patients in the augmented and nonaugmented groups who did not experience graft failure (Lysholm score, 88 vs 92; Tegner score, 6.4 vs 6.3; single-assessment numeric evaluation score, 86 vs 86; satisfaction, 8.4 vs 8.9, respectively). Conclusion: Adolescents undergoing an ACL reconstruction frequently have small hamstring tendon autograft size. The augmentation of these small grafts with allograft does not reduce graft failure rates and may in fact lead to higher retear rates, with earlier graft failure.

Impact of cement-augmented condylar screws in locking plate osteosynthesis for distal femoral fractures — A biomechanical analysis

IntroductionCompromised bone quality and the need for early mobilization continue to lead to implant failure in elderly patients with distal femoral fractures. The cement augmentation of screws might facilitate improving implant anchorage. The aim of this study was to analyse the impact of cement augmentation of the condylar screws on implant fixation in a human cadaveric bone model. Material and methodsTen pairs of osteoporotic femora (mean age: 90 years, range: 84–99 years) were used. A 2-cm gap osteotomy was created in the metaphyseal region to simulate an unstable AO/OTA 33-A3 fracture. All specimens were treated with a polyaxial locking plate. Specimens randomly assigned to the augmented group received an additional cement augmentation of the condylar screws using bone cement. A servohydraulic testing machine was used to perform incremental cyclic axial loading using a load-to-failure mode. ResultsAll specimens survived at least 800N of axial compressive force. The mean compressive forces leading to failure were 1620N (95% CI: 1382–1858N) in the non-augmented group and 2420N (95% CI: 2054–2786N) in the group with cement-augmented condylar screws (p=0.005).Deformation with cutting out of the condylar screws and condylar fracture were the most common reasons for failure in both groups. Whereas axial stiffness was comparable between both osteosyntheses (p=0.508), significant differences were observed for the plastic deformation of the constructs (p=0.014). ConclusionThe results of the present study showed that the cement augmentation of the condylar screws might be a promising technique for the fixation of distal femoral fractures in elderly patients with osteoporotic bones.

Effect of fibrin glue on corneal lamellar healing and how it correlates to biomechanical properties: biomechanical wavefront analysis and confocal study.

BackgroundTo evaluate, using a rabbit model, the influence of the wound healing process at the flap edge on corneal biomechanics after sutured, glued, and non-augmented microkeratome flaps.MethodsUnilateral 160 μm thick laser in situ keratomileusis (LASIK) flaps using a mechanical microkeratome were performed on the corneas of the left eyes of 36 rabbits. Animals were then divided into 3 groups of 12 rabbits each: A: the flaps were glued with human fibrin tissue adhesive (Tisseel); B: the flaps were sutured; and C: the flaps were allowed to heal without the use of sutures or glue (non-augmented). The contralateral eyes served as controls. Reichert ocular response analyzer (ORA) was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and cornea-compensated IOP (IOPcc) at 6 weeks and 3 months postoperatively. In vivo confocal microscopy (IVCM) was also used to study the corneal wound healing process in all groups.ResultsBoth mean CH and mean CRF were significantly higher in sutured and glued groups compared with the non-augmented group at 6 weeks and 3 months postoperatively (P < 0.0001). No statistically significant difference in corneal biomechanics was found between controls and groups A and B at any time points. Activated keratocytes were detected at the wound edge and peripheral flap interface in sutured and glued groups.ConclusionThe healing process at the wound edge is critical for optimal corneal integrity. Fibrin glue may serve as a safe and effective substitute to sutures in enhancing the corneal flap edge healing response and in increasing its mechanical strength.

Augmentation technique on the proximal humerus

The treatment of osteoporotic fractures is still a challenge. The advantages of augmentation with respect to primary in vitro stability and the clinical use for the proximal humerus are presented in this article. In this study six paired human humeri were randomized into an augmented and a non-augmented group. Osteosynthesis was performed with a PHILOS plate (Synthes®). In the augmented group the two screws finding purchase in the weakest cancellous bone were augmented. The specimens were tested in a 3-part fracture model in a varus bending test. The augmented PHILOS plates withstood significantly more load cycles until failure. The correlation to bone mineral density (BMD) showed that augmentation could partially compensate for low BMD. The augmentation of the screws in locked plating in a proximal humerus fracture model is effective in improving the primary stability in a cyclic varus bending test. The targeted augmentation of two particular screws in a region of low bone quality within the humeral head was almost as effective as four screws with twice the amount of bone cement. Screw augmentation combined with a knowledge of the local bone quality could be more effective in enhancing the primary stability of a proximal humerus locking plate because the effect of augmentation can be exploited more effectively limiting it to the degree required. The technique of augmentation is simple and can be applied in open and minimally invasive procedures. When the correct procedure is used, complications (cement leakage into the joint) can be avoided.

Implant augmentation: adding bone cement to improve the treatment of osteoporotic distal femur fractures: a biomechanical study using human cadaver bones.

The increasing problems in the field of osteoporotic fracture fixation results in specialized implants as well as new operation methods, for example, implant augmentation with bone cement. The aim of this study was to determine the biomechanical impact of augmentation in the treatment of osteoporotic distal femur fractures.Seven pairs of osteoporotic fresh frozen distal femora were randomly assigned to either an augmented or nonaugmented group. In both groups, an Orthopaedic Trauma Association 33 A3 fractures was fixed using the locking compression plate distal femur and cannulated and perforated screws. In the augmented group, additionally, 1 mL of polymethylmethacrylate cement was injected through the screw. Prior to mechanical testing, bone mineral density (BMD) and local bone strength were determined. Mechanical testing was performed by cyclic axial loading (100 N to 750 N + 0.05N/cycle) using a servo-hydraulic testing machine.As a result, the BMD as well as the axial stiffness did not significantly differ between the groups. The number of cycles to failure was significantly higher in the augmented group with the BMD as a significant covariate.In conclusion, cement augmentation can significantly improve implant anchorage in plating of osteoporotic distal femur fractures.

Biomechanical evaluation of expansive pedicle screws and injectable absorbable bone cement augmentation in the osteoporotic vertebral environment

Objective To evaluate the fixation strengths of expansive pedicle screws in human cadaveric vertebrae with different bone mineral densities and with the augmentation by newly-developed injectable absorbable bone cement(IABC).Methods Fresh human cadaveric spines used for this study were grouped into 4 levels according to the measurements of bone mineral density:normal,osteopenia,osteoporosis and severe osteoporosis.The vertebrae were bilaterally instrumented with 4 pedicle screw protocols:conventional pedicle screw without augmentation,expansive pedicle screw without augmentation,conventional pedicle screw with augmentation and expansive pedicle screw with augmentation.The statistical method of balanced incomplete randomized blocks was used to assign the pedicles for the 4 protocols,resulting in 9 screws per group per level.Screw pullout tests were conducted.On the load-stroke curve,the maximum pullout strength and stiffness were determined.The differences between groups at the same bone mineral density level but with different screw protocols,or between groups at different bone mineral density levels but with the same screw protocol,were compared.Results Given the same bone mineral density level,the maximum pullout strength and stiffness of expansive screws were significantly higher than those of conventional screws (P ＜ 0.05).When the same type of screw was used,the maximum pullout strength in the augmented group was significantly higher than in the non-augmented group (P ＜ 0.05),but the cement augmentation had insignificant impact on the stiffness of either conventional or expansive pedicle screws (P ＞ 0.05).The pullout strength and stiffness of expansive screws,augmented conventional screws and augmented expansive screws at the osteoporotic level were comparable to those of conventional screws at the osteopenic lcvel (P ＞ 0.05).However,the pullout strength of any of the 4 protocols in the severe osteoporosis group was significantly lower than that of conventional screws in the osteopenia group (P ＜ 0.05).Conclusions Expansive pedicle screws appear feasible and safe in either osteopenic or osteoporotic spines.Augmentation by the newly-developed IABC can further improve the initial fixation strength of either conventional or expansive pedicle screws. Key words: Osteoporosis; Bone screw; Biomechanics; Cement; Pedicle screw augmentation

Metaphyseal Screw Augmentation of the LISS-PLT Plate With Polymethylmethacrylate Improves Angular Stability in Osteoporotic Proximal Third Tibial Fractures

The incidence of osteoporotic proximal tibial fractures has increased during the last 2 decades. A promising approach in osteoporotic fracture fixation is polymethylmethacrylate-based cement augmentation of implants to gain better implant purchase in the bone. This study investigates the biomechanical benefits of screw augmentation in less invasive stabilization system-proximal lateral tibial (LISS-PLT) plates in cadaveric extraarticular comminuted proximal tibial fractures (OTA-41-A3.3). Standardized extraarticular proximal tibial fractures were stabilized with the LISS-PLT plate in 6 paired osteoporotic cadaveric tibiae. Bone mineral density was measured with high-resolution, quantitative computed tomography scans to identify bone quality. In the augmented group, the 5 proximal screws of the LISS-PLT plate were augmented with 1 mL of bone cement each, whereas the contralateral tibia was instrumented conventionally as the control. Cyclic axial loading was applied to each specimen with a starting load of 150 N, using a ramp of 0.05 N per cycle to 10-mm axial displacement. Varus displacement was identified from anterior-posterior radiographs. Bone mineral density showed no significant difference between the 2 groups (P = 0.47). The nonaugmented group reached 9417 load cycles (SD 753) until failure, compared with 14,792 load cycles (SD 2088) in the augmented group (P = 0.002). In the early-onset failure (deformation at 8250 load cycles), varus displacement was significantly smaller in the augmented group (0.46 degrees, SD 0.6) than in the nonaugmented group (3.23 degrees, SD 1.7) (P = 0.01). This biomechanical study showed that cement augmentation of the LISS-PLT plate screws in osteoporotic proximal extraarticular tibial fractures significantly lowers the propensity toward screw migration and secondary varus displacement.

Surgical Strategies to Improve Fixation in the Osteoporotic Spine: the Effects of Tapping, Cement Augmentation, and Screw Trajectory

Study Design Biomechanical study of pedicle screw fixation in osteoporotic bone. Objective To investigate whether it is better to tap or not tap osteoporotic bone prior to placing a cement-augmented pedicle screw. Methods Initially, we evaluated load to failure of screws placed in cancellous bone blocks with or without prior tapping as well as after varying the depths of tapping prior to screw insertion. Then we evaluated load to failure of screws placed in bone block models with a straight-ahead screw trajectory as well as with screws having a 23-degree cephalad trajectory (toward the end plate). These techniques were tested with nonaugmented (NA) screws as well as with bioactive cement (BioC) augmentation prior to screw insertion. Results In the NA group, pretapping decreased fixation strength in a dose-dependent fashion. In the BioC group, the tapped screws had significantly greater loads to failure (p < 0.01). Comparing only the screw orientation, the screws oriented at 23 degrees cephalad had a significantly higher failure force than their respective counterparts at 0 degrees (p < 0.01). Conclusions Standard pedicle screw fixation is often inadequate in the osteoporotic spine, but this study suggests tapping prior to cement augmentation will substantially improve fixation when compared with not tapping. Angulating screws more cephalad also seems to enhance aging spine fixation.

A New Anchor Augmentation Technique With a Cancellous Screw in Osteoporotic Rotator Cuff Repair: An In Vitro Biomechanical Study on Sheep Humerus Specimens

The aim of this study was to test a simple technique to augment the pullout resistance of an anchor in an over-drilled sheep humerus model. Sixty-four paired sheep humeri were harvested from 32 male sheep aged 18 months. Specimens were divided into an augmented group and non-augmented group. FASTIN RC 5-mm titanium screw anchors (DePuy Mitek, Raynham, MA) double loaded with suture material (braided polyester, nonabsorbable USP No. 2) were used in both groups. Osteoporosis was simulated by over-drilling with a 4.5-mm drill. Augmentation was performed by fixing 1 of the sutures 1.5 cm inferior to the anchor insertion site with a washer screw. This was followed by a pull-to-failure test at 50 mm/min. The ultimate load (the highest value of strength before anchor pullout) was recorded. A paired t test was used to compare the biomechanical properties of the augmented and non-augmented groups. In all specimens the failure mode was pullout of the anchor. The ultimate failure loads were statistically significantly higher in the augmented group (P < .0001). The mean pullout strength was 121.1 ± 10.17 N in the non-augmented group and 176.1 ± 10.34 N in the augmented group. The described augmentation technique, which is achieved by inferior-lateral fixation of 1 of the sutures of the double-loaded anchor to a fully threaded 6.5-mm cancellous screw with a washer, significantly increases the ultimate failure loads in the over-drilled sheep humerus model. Our technique is simple, safe, and inexpensive. It can be easily used in all osteoporotic patients and will contribute to the reduction of anchor failure. This technique might be difficult to apply arthroscopically. Cannulated smaller screws would probably be more practical for arthroscopic use. Further clinical studies are needed.

Feasibility study on the potential of a spiral blade in osteoporotic distal femur fracture fixation

Osteoporotic fractures of the distal femur (primary as well as periprosthetic) are a growing problem in today's trauma and orthopaedic surgery. Therefore, this feasibility study should identify the biomechanical potential of a (commercially available) spiral blade in the distal femur as compared to a single screw without any additional plate fixation. Additionally, the influence of cement augmentation was investigated. An artificial low density bone model was either instrumented with a perforated spiral blade or a 5 mm locking screw only. Additionally, the influence of 1 ml cement augmentation was investigated. All specimens were tested with static pull-out and cyclic loading (50 to 250 N with an increment of 0.1 N/cycle). In the non-augmented groups, the mean pull-out force was significantly higher for the blade fixation (p < 0.001). In the augmented groups, the difference was statistically not significant (p = 0.217). Augmentation could increase pull-out force significantly by 72 % for the blade and 156 % for the screw, respectively (p = 0.001). The mean number of cycles to failure in the non-augmented groups was 12,433 (SD 465) for the blade and 2,949 (SD 215) for the screw, respectively (p < 0.001). In the augmented group, the blade reached 13,967 (SD 1,407) cycles until failure and the screw reached 4,413 (SD 1,598), respectively (p < 0.001). The investigated spiral blade was mechanically superior, significantly, as compared to a screw in the distal femur. These results back up the further development of a distal femoral blade with spiral blade fixation for the treatment of osteoporotic distal femur fractures.

A laboratory investigation to assess the influence of cement augmentation of screw and plate fixation in a simulation of distal femoral fracture of osteoporotic and non-osteoporotic bone

The augmentation of fixation with bone cement is increasingly being used in the treatment of severe osteoporotic fractures. We investigated the influence of bone quality on the mechanics of augmentation of plate fixation in a distal femoral fracture model (AO 33 A3 type). Eight osteoporotic and eight non-osteoporotic femoral models were randomly assigned to either an augmented or a non-augmented group. Fixation was performed using a locking compression plate. In the augmented group additionally 1 ml of bone cement was injected into the screw hole before insertion of the screw. Biomechanical testing was performed in axial sinusoidal loading. Augmentation significantly reduced the cut-out distance in the osteoporotic models by about 67% (non-augmented mean 0.30 mm (sd 0.08) vs augmented 0.13 mm (sd 0.06); p = 0.017). There was no statistical reduction in this distance following augmentation in the non-osteoporotic models (non-augmented mean 0.15 mm (sd 0.02) vs augmented 0.15 mm (sd 0.07); p = 0.915). In the osteoporotic models, augmentation significantly increased stability (p = 0.017).

Effect of Platelet-Rich Plasma and Porcine Dermal Collagen Graft Augmentation for Rotator Cuff Healing in a Rabbit Model

Background: The rate of healing failure after surgical repair of chronic rotator cuff tears is considerably high. Purpose: To verify the effect of platelet-rich plasma (PRP) with and without porcine dermal collagen graft augmentation on tendon-to-bone healing, using the rabbit supraspinatus tendon. Study Design: Controlled laboratory study. Methods: A total of 80 rabbits were randomly allocated into 4 groups (20 rabbits per group: 12 for histological and 8 for mechanical testing): repair (R), repair + patch augmentation (RPa), repair + PRP (RPr), and repair + patch + PRP (RPaPr). The right shoulder was used for experimental interventions, and the left served as a control. Six weeks after the detachment of the supraspinatus, the torn tendon was repaired in a transosseous manner, simulating double-row repair in all groups. Platelet-rich plasma was prepared and applied onto the repair site in the RPr and RPaPr groups, and the patch was used to augment the repair in the RPa and RPaPr groups. The mechanical tensile strength test was performed at 8 weeks after repair and the histological evaluation at 4 and 8 weeks. Results: At 4 weeks, the collagen fibers were poorly organized, and fiber continuity was not established in all groups. However, vascularity and cellularity were higher with granulation tissue formation in the PRP-treated groups (RPr and RPaPr) than the nontreated groups (R and RPa). At 8 weeks, tendon-to-bone integration was much improved with more collagen fibers, and longitudinally oriented collagen fibers were visible in all groups. The PRP-treated groups showed better collagen fiber continuity and orientation than the nontreated groups; however, no distinctive difference was found between the patch-augmented groups (RPa and RPaPr) and nonaugmented groups (R and RPr). The mean load-to-failure results were 61.57 ± 29.99 N, 76.84 ± 16.08 N, 105.35 ± 33.82 N, and 117.93 ± 12.60 N for the R, RPa, RPr, and RPaPr groups, respectively, and they were significantly different between the R and RPr (P = .018), R and RPaPr (P = .002), and RPa and RPaPr (P = .029) groups. Conclusion: This animal study showed the enhancement of tendon-to-bone healing after local administration of autologous PRP assessed by histological and biomechanical testing in a rabbit model of chronic rotator cuff tears. However, there was little additive effect of the patch graft. Clinical Relevance: The use of PRP might be a biological supplement to increase the rotator cuff healing rate, which still remains low even after successful cuff repair, but this result should be interpreted with caution regarding clinical applications.

Cement augmentation of the proximal femoral nail antirotation for the treatment of osteoporotic pertrochanteric fractures—A biomechanical cadaver study

IntroductionProximal femoral fractures will gain increasing importance in the future due to the epidemiological development. Osteoporosis is often a limiting factor in the achievement of implant stability. New nailing systems offer the possibility of augmentation of the femoral neck component with cement. The aim of this study was to perform a biomechanical comparison of implant stability in osteoporotic pertrochanteric fractures using the proximal femoral nail antirotation (PFNA, Synthes GmbH, Umkirch, Germany) with cement augmented and non-augmented blades. Materials and methodsBone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DEXA) in six pairs of fresh-frozen human femurs. Standardised pertrochanteric fractures (AO31-A2.3) were treated with a PFNA. Cement augmentation was performed in six constructs. Axial loading was applied according to a single-leg-stance model using a hydraulic testing machine increasing to 1400N over 10,000 cycles. Biomechanical comparisons between the two groups that were comparable concerning BMD, tip-apex-distance and native stiffness were made with regard to postoperative stiffness, survived cycles, load to failure, failure mechanism and axial displacement. ResultsThe stiffness of all stabilised femurs was significantly lower than for native specimens (native 702.5±159.6N/mm vs. postoperative 275.4±53.8N/mm, p<0.001). Stiffness after instrumentation was significantly greater for the cement augmented group than for the non-augmented group (300.6±46.7N/mm vs. 250.3±51.6N/mm, respectively, p=0.001). Five of the twelve constructs survived cyclic testing. Statistically significant differences of the BMD were detected between survived and failed constructs (0.79±0.17g/cm2 vs. 0.45±0.12g/cm2, respectively, p=0.028). The failure loads for specimens surviving 10,000 cycles were 4611.9±2078.9N in the cement augmented group (n=3) and 4516.3N and 3253.5N in the non-augmented group (n=2). Postoperative stiffness was found to be a positive predictor of maximum force to failure (R2=0.83, p=0.02). ConclusionsThe results of this biomechanical study show that cement augmentation of the PFNA increases the implant stability in osteoporotic pertrochanteric fractures. Further studies are necessary to evaluate this procedure in providing long term clinical results.

Cement augmentation of lag screws: an investigation on biomechanical advantages

In trauma surgery, lag screws are commonly used. However, in osteoporotic bone, anchorage can be considerably compromised. This study investigates the biomechanical potential of cement augmentation in terms of improved fixation. 36 Surrogate osteoporotic bone specimens were utilised in three biomechanical experiments, each comparing 6 augmented with 6 non-augmented samples. Standard partially-threaded lag screws (Synthes) were placed following surgical standard. For the augmented groups, 0.4ml of polymethylmethacrylate was injected into the pre-drilled hole prior to screw placement. Interfragmentary compression was determined using a cannulated ring compression sensor. Maximum torque was recorded with a torque wrench. Compressive relaxation after 24h, relaxation after loosening and re-tightening the screw as well as maximum compression and torque at failure were measured. Mean relaxation was significantly lower for the augmented group (p<0.01). After 24h, a remaining fragmental compression of 62% for the augmented and 52% for the non-augmented specimens was found. Loosening and re-tightening of the screw did not affect the compressive relaxation when augmentation was applied (p=0.529), compared to an increased relaxation after re-tightening in the non-augmented group (p=0.04). The mean maximum compression and torque until failure were significantly higher for the augmented group (p<0.001). Cement augmentation of lag screws can improve fixation stability in terms of installing and maintaining interfragmentary compression. Effects of relaxation can be reduced and re-tightening of screws is possible without compromising the fixation. Particularly in reduced bone mass, augmentation of lag screws can markedly increase the security of the technique.

Distal radius fracture fixation with volar locking plates and additional bone augmentation in osteoporotic bone: a biomechanical study in a cadaveric model

Fractures of the distal radius represent the most common fractures in adults. Volar locked plating has become a popular method for treating these fractures, but has been subject to several shortcomings in osteoporotic bone, such as loss of reduction and screw purchase. In order to overcome these shortcomings, cement augmentation has been proposed. AO-type 23-A3.3 fractures were made in 8 pairs of fresh frozen osteoporotic cadaveric radial bones. All specimens were treated with volar plating, and divided into cement augmentation or non-augmentation groups (n = 8/group). Constructs were tested dynamically and load to failure, construct-stiffness, fracture gap movement and screw cutting distance were measured. Cement augmentation resulted in a significant increase in cycles and load to failure, as well as construct stiffness at loads higher than 325 N. When compared to the non-augmented group, fracture gap movement decreased significantly at this load and higher, as did screw cutting distance at the holes of the ulnar column. The cycles to failure depend on the BMD in the distal region of the radius. Cement augmentation improves biomechanical properties in volar plating of the distal radius.

The potential of implant augmentation in the treatment of osteoporotic distal femur fractures: A biomechanical study

PurposeOsteoporotic fractures of the distal femur are an underestimated and increasing problem in trauma and orthopaedic surgery. Therefore, this study investigates the biomechanical potential of implant augmentation in the treatment of these fractures. MethodsTwelve osteoporotic surrogate distal femora were randomly assigned to the augmented or non-augmented group. All specimens were fixed using the LCP DF. In the augmented group additionally 1ml Vertecem V+ was injected in each screw hole before screw positioning. The construct represents an AO 33 A3 fracture. Biomechanical testing was performed as sinusoidal axial loading between 50 and 500N with 2Hz for 45,000 cycles, followed by loading between 50 and 750N until failure. ResultsThe augmented group showed significant higher axial stiffness (36%). Additionally the displacement after 45,000 cycles was 3.4 times lower for the augmented group (0.68±0.2mm vs. 2.28±0.2mm). Failure occurred after 45,130 cycles (SD 99) in all of the non-augmented specimens and in two specimens of the augmented group after 69,675 cycles (SD 1729). Four of the augmented specimens showed no failure. The failure mode of all specimens in both groups was a medial cut-out. ConclusionsThis study shows a promising potential of implant augmentation in the treatment of osteoporotic distal femur fractures.

Medial Rectus Surgery for Convergence Excess Esotropia with an Accommodative Component: A Comparison of Augmented Recession, Slanted Recession, and Recession with Posterior Fixation

Richard G. Scobee was an internationally renowned strabismologist whose life was short yet very productive. The first section of this paper describes his life and contributions to strabismology and orthoptics. The second section of this paper reports the results of our strabismological study.Introduction and PurposeMany different surgical procedures exist for the treatment of children or adults with convergence excess esotropia. We report on our results of augmented recession, slanted recession, and recession with posterior fixation of the medial rectus muscle in such situations. We also report on the incidence of induced vertical deviations.MethodsUsing a retrospective chart review of 800 patients, we excluded patients with confounding strabismus conditions and pharmacological treatments leaving 131 patients included in the study. Slanted reinsertion of medial rectus (twenty-seven patients); posterior fixation with recession of medial rectus (twenty-two patients); augmented medial rectus recession (fifty-eight patients); nonaugmented recession of medial rectus (seventy-three patients). The distance near disparity postoperatively was evaluated using a life table analysis in which all patients were grouped according to the length of time postoperatively. Induced vertical deviation was evaluated at least 6 months postoperatively.ResultsAt all time periods postoperatively, the patients with slanted recessions showed the greatest reduction in distance near disparity and that reduction was the most stable over time. At 12–14 months postoperatively, the range in reduction measured 7.9–11Δ among all three procedures. At 15–18 months postoperatively, the range in reduction measured 16.9–19.3Δ diopters among the three procedures. At greater than 6 months postoperatively, the slanted and augmented recession groups showed up to 1Δ of right hypertropia and the posterior fixation and nonaugmented groups showed up to 0.6Δ of left hypertropia.ConclusionsAll three medial rectus procedures used in our retrospective study (slanted recession, augmented recession, recession with posterior fixation) reduced the distance near disparity. The greatest and most stable reduction at all time periods postoperatively occurred with the slanted recession. The induced vertical deviation is small in all procedures and is acceptable at 1Δ or less. The augmented and slanted recessions are easier to perform than the posterior fixation with recession. We recommend that the slanted reinsertion of the medial rectus recession be considered as a viable option in the surgical correction of esotropia with a distance near disparity.

A Prospective, Randomized Evaluation of Acellular Human Dermal Matrix Augmentation for Arthroscopic Rotator Cuff Repair

To prospectively evaluate the safety and effectiveness of arthroscopic acellular human dermal matrix augmentation of large rotator cuff tear repairs. A prospective, institutional review board-approved, multicenter series of patients undergoing arthroscopic repair of 2-tendon rotator cuff tears measuring greater than 3 cm were randomized by sealed envelopes opened at the time of surgery to arthroscopic single-row rotator cuff repair with GraftJacket acellular human dermal matrix (Wright Medical Technology, Arlington, TN) augmentation (group 1) or without augmentation (group 2). Preoperative and postoperative functional outcome assessments were obtained by use of the American Shoulder and Elbow Surgeons (ASES), Constant, and University of California, Los Angeles scales. Gadolinium-enhanced magnetic resonance imaging (MRI) evaluation of these repairs was obtained at a mean of 14.5 months (range, 12 to 24 months). Adverse events were recorded. There were 22 patients in group 1 and 20 in group 2 with a mean age of 56 years. The mean follow-up was 24 months (range, 12 to 38 months). The ASES score improved from 48.5 to 98.9 in group 1 and from 46.0 to 94.8 in group 2. The scores in group 1 were statistically better than those in group 2 (P = .035). The Constant score improved from 41.0 to 91.9 in group 1 and from 45.8 to 85.3 in group 2. The scores in group 1 were statistically better than those in group 2 (P = .008). The University of California, Los Angeles score improved from 13.3 to 28.2 in group 1 and from 15.9 to 28.3 in group 2 (P = .43). Gadolinium-enhanced MRI scans showed intact cuffs in 85% of repairs in group 1 and 40% in group 2 (P < .01). No adverse events were attributed to the presence of the matrix grafts. Acellular human dermal matrix augmentation of large (>3 cm) cuff tears involving 2 tendons showed better ASES and Constant scores and more frequent intact cuffs as determined by gadolinium-enhanced MRI. Intact repairs were found in 85% of the augmented group and 40% of the nonaugmented group (P < .01). No adverse events related to the acellular human dermal matrix were observed. Level II, lesser-quality randomized controlled trial.

Detrusor Wraparound for Bladder Neck Reconstruction in Cohort of Children With Bladder Exstrophy

To evaluate the outcome of the detrusor wraparound bladder neck technique of bladder neck reconstruction in 28 children with bladder exstrophy. The records of all patients with bladder exstrophy who underwent detrusor wraparound bladder neck were reviewed. A total of 28 consecutive patients were identified and included 21 boys and 7 girls, with a mean age at surgery of 8.3 years. All patients had undergone previous exstrophy closure (17 staged and 11 complete). Of the 28 patients, 8 (29%) had undergone previous endoscopic injection of a bulking agent at the bladder neck. At surgery, 13 patients (46%) required concomitant ileocystoplasty and a continent outlet. Continence was defined as complete dryness with no urine leakage either through the urethra or the continent outlet. The mean follow-up duration was 31 months (range 13-48). All augmented patients were continent using clean intermittent catheterization through the outlet. Complete dryness was achieved in 20 (71%) of 28 patients. However, the continence rate was only 47% in the nonaugmented group compared with 100% in the augmented group. Six of the incontinent children underwent bladder neck injection using a bulking agent but dryness was achieved in only 1 (17%). The detrusor wraparound bladder neck technique is a viable option for bladder neck reconstruction for incontinent children after exstrophy closure. However, bladder augmentation and continent outlet construction are the pillars of optimal success. Injection of bulking agent at the bladder neck for failure has had poor success.

Biomechanical effect of bone cement augmentation on rotational stability and pull-out strength of the Proximal Femur Nail Antirotation™

Introduction After surgical treatment of osteoporotic hip fractures, complications such as implant cut-out are reported to be high and implant failure often is associated with poor bone quality. As augmentation is reported to enhance implant anchorage, the aim of our study was to investigate the effect of bone cement augmentation on the rotational stability and the pull-out resistance of the Proximal Femur Nail Antirotation™ (PFNa) blade. Materials and methods A total of 18 fresh-frozen femoral heads (mean age 68 years, standard deviation (SD) 8.2) were scanned with quantitative computed tomography (qCT) for bone mineral density (BMD) measurements and instrumented with a PFNa blade. Nine specimens were augmented with a mean volume of 4.4 ml Traumacem V+. After cement consolidation, the blade was rotated for 60° for the rotational test. Subsequently, the blade was extracted from the specimens. Force, torque, displacement and angle were recorded constantly. Results In the rotational test, the mean maximum torque in the augmented group (17.2 Nm, SD 5.0) was significantly higher ( p = 0.017) than in the non-augmented group (11.7 Nm, SD 3.5). The pull-out test also yielded a significant difference ( p = 0.047) between the augmented (maximum pullout force: 2315.2 N, SD 1060.6) and the non-augmented group (1180.4 N, SD 1171.4). Discussion Augmentation of femoral heads yielded a significantly superior rotational stability, as well as an enhanced pull-out resistance, compared to the non-augmented state. However, the higher the BMD of the specimens, the lower was the effect of augmentation on the rotational stability. Therefore, augmentation can be a good clinical tool to enhance implant anchorage in osteoporotic bone.