Biomechanical testing of suture-based meniscal repair devices containing ultrahigh-molecular-weight polyethylene suture: update 2011

PURPOSE

To evaluate the biomechanical characteristics of recently introduced ultrahigh-molecular-weight polyethylene suture-based, self-adjusting meniscal repair devices.

METHODS

Updating a prior study published in 2009, we made vertical longitudinal cuts 3 mm from the periphery in fresh-frozen adult human menisci to simulate a bucket-handle meniscus tear. Each tear was then repaired by a single repair technique in 10 meniscus specimens. Group 1 menisci were repaired with a vertical mattress suture of No. 2-0 Ethibond (Ethicon, Somerville, NJ). Group 2 menisci were repaired with a vertical mattress suture of No. 2-0 OrthoCord (DePuy Mitek, Raynham, MA). Group 3 menisci were repaired with a single OmniSpan device with No. 2-0 OrthoCord suture (DePuy Mitek). Group 4 menisci were repaired with a single Meniscal Cinch device with No. 2-0 FiberWire suture (Arthrex, Naples, FL). Group 5 menisci were repaired with a single MaxFire device inserted with the MarXmen gun (Biomet Sports Medicine, Warsaw, IN). Group 6 menisci were repaired with a Sequent device with No. 0 Hi-Fi suture (ConMed Linvatec, Largo, FL) in a "V" suture configuration. Group 7 menisci were repaired with a single FasT-Fix 360 device (Smith & Nephew Endoscopy, Andover, MA). By use of a mechanical testing machine, all samples were preloaded at 5 N and cycled 200 times between 5 and 50 N. Those specimens that survived were destructively tested at 5 mm/min. Endpoints included maximum load, displacement, stiffness, and failure mode.

RESULTS

Mean failure loads were as follows: Ethibond suture, 73 N; OrthoCord suture, 88 N; OmniSpan, 88 N; Cinch, 71 N; MarXmen/MaxFire, 54 N; Sequent, 66 N; and FasT-Fix 360, 60 N. Ethibond was stronger than MarXmen/MaxFire. The mean displacement after 100 cycles was as follows: Ethibond, 2.58 mm; OrthoCord, 2.75 mm; OmniSpan, 2.51 mm; Cinch, 2.65 mm; MarXmen/MaxFire, 3.67 mm; Sequent, 3.35 mm; and FasT-Fix 360, 1.13 mm. The MarXmen/MaxFire showed greater 100-cycle displacement than Ethibond and FasT-Fix 360. No difference in stiffness existed for these devices, and failure mode varied without specific trends.

CONCLUSIONS

The biomechanical properties of meniscal repairs using the OmniSpan, Cinch, Sequent, and FasT-Fix 360 devices are equivalent to suture repair techniques. However, the MarXmen/MaxFire meniscal repair device showed significantly lower failure loads and survived less cyclic loading in the human cadaveric meniscus than other tested repairs.

CLINICAL RELEVANCE

Most commercially available devices for all-inside meniscal repair using ultrahigh-molecular-weight polyethylene suture provide fixation comparable to the classic vertical mattress suture repair technique in human cadaveric meniscus.

Biomechanical comparison of tibial eminence fracture fixation with high-strength suture, EndoButton, and suture anchor

PURPOSE

To biomechanically compare anterior cruciate ligament (ACL) tibial bony avulsion fixation by suture anchors, EndoButtons (Smith & Nephew, Andover, MA), and high-strength sutures subjected to cyclic loading.

METHODS

Type III tibial eminence fractures were created in 49 ovine knees, and 7 different types of repairs were performed. Each repair group contained 7 specimens. The repair groups were as follows: No. 2 FiberWire (Arthrex, Naples, FL); No. 2 UltraBraid (Smith & Nephew); No. 2 MaxBraid (Arthrotek, Warsaw, IN); No. 2 Hi-Fi (ConMed Linvatec, Largo, FL); No. 2 OrthoCord (DePuy Mitek, Raynham, MA); Ti-Screw suture anchor (Arthrotek); and titanium EndoButton. These constructs were cyclically loaded (500 cycles, 0 to 100 N, 1 Hz) in the direction of the native ACL and loaded to failure (100 mm/min). Endpoints included ultimate failure load (in Newtons); pullout stiffness (in Newtons per millimeter); cyclic displacement (in millimeters) after 100 cycles, between 100 and 500 cycles, and after 500 cycles; and mode of failure. Bone density testing was performed in all knees.

RESULTS

Bone density was not different among the groups. The EndoButton group had a higher ultimate failure load than the FiberWire, UltraBraid, Hi-Fi, and suture anchor groups (P < .05). The MaxBraid and OrthoCord groups had higher failure loads than the suture anchor group (P < .05). The MaxBraid group also had a higher failure load than the Hi-Fi group (P < .05). Stiffness was not statistically different for the various tested constructs. After 100 cycles, the EndoButton group had less displacement than the FiberWire, UltraBraid, MaxBraid, and Hi-Fi groups (P < .05). The suture anchor group had less displacement than the Hi-Fi and FiberWire groups (P < .05). The displacements of the different tested constructs between 100 and 500 cycles and total displacements after 500 cycles were not statistically different. The predominant failure mode was suture rupture.

CONCLUSIONS

Under cyclic loading conditions in an ovine model, EndoButton fixation of tibial eminence fractures provided greater initial fixation strength than suture anchor fixation or fixation with various high-strength sutures except for OrthoCord.

CLINICAL RELEVANCE

During initial cyclic loading of ACL tibial eminence fractures, the strength of the repair construct should be taken into consideration because conventional suture repair even with ultrahigh-molecular-weight polyethylene sutures may not provide enough strength.

A prospective, randomized evaluation of acellular human dermal matrix augmentation for arthroscopic rotator cuff repair

PURPOSE

To prospectively evaluate the safety and effectiveness of arthroscopic acellular human dermal matrix augmentation of large rotator cuff tear repairs.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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 OF EVIDENCE

Level II, lesser-quality randomized controlled trial.

Tendon-grasping strength of various suture configurations for rotator cuff repair

PURPOSE

The purpose of the present study is to evaluate the mechanical performance and initial strength of the arthroscopic Mason-Allen, double mattress, inclined Mason-Allen, and lasso loop stitch configurations.

METHODS

Using 36 sheep infraspinatus tendons, tendon widths and thicknesses were measured with a digital caliper to confirm standardization of the tendons. Four different stitch configurations (Mason-Allen, inclined Mason-Allen, double mattress, and lasso loop) were biomechanically tested with cyclic loading followed by load to failure testing. The cyclic elongation, peak-to-peak displacement, ultimate tensile strength, stiffness, and mode of failure were recorded.

RESULTS

Mean tendon widths and thicknesses were statistically the same. The lasso loop (0.7 ± 0.1 mm) demonstrated a mean cyclic elongation greater than the Mason-Allen (0.5 ± 0.3 mm) and double mattress (0.5 ± 0.3 mm) groups (P = 0.011; P = 0.013). No differences were found in ultimate failure load, stiffness, and peak-to-peak displacement for the Mason-Allen (mean 99 ± 42 N, 39 ± 9 N/mm, 0.6 ± 0,1 mm), inclined Mason-Allen (113 ± 52 N, 44 ± 14 N/mm, 0.5 ± 0.1 mm), double mattress stitch (119 ± 68 N, 45 ± 10 N/mm, 0.5 ± 0.1 mm), or lasso loop (100 ± 38 N, 42 ± 7 N/mm, 0.5 ± 0.1 mm) groups (n.s.). Each specimen failed at the suture-tendon interface. Three specimens (two Mason-Allen and one inclined Mason-Allen) failed during cyclic testing.

CONCLUSION

Conventional Mason-Allen configuration can be applied with double-loaded suture anchor safely. Recent modifications of the configurations offer no biomechanical advantage.

Platelet-rich plasma products in sports medicine

Platelet-rich plasma (PRP) therapy is a recently developed technique that uses a concentrated portion of autologous blood to try to improve and accelerate the healing of various tissues. There is considerable interest in using these PRP products for the treatment of musculoskeletal disorders, particularly athletic injuries. Because PRP products are safe and easy to prepare and administer, there has been increased attention toward using PRP in numerous clinical settings. Platelet-rich plasma has been used to treat conditions such as lateral epicondylitis, ligament and muscle strains, and tears of the rotator cuff, anterior cruciate ligament, and Achilles tendon. Platelet-rich plasma can be applied at the site of injury either during surgery or through an injection performed in the physician's office. The benefits of PRP therapy appear to be promising, and many investigators are exploring the ways in which this therapy can be used in the clinical setting. However, there is little published clinical evidence that proves its efficacy in treating the multitude of injuries/disorders that are thought to benefit from PRP. The purpose of this article is to review the current evidence on PRP therapy.

Rotator cuff repair healing influenced by platelet-rich plasma construct augmentation

PURPOSE

To assess the effect of platelet-rich plasma fibrin matrix (PRPFM) construct augmentation on postoperative tendon healing as determined by magnetic resonance imaging (MRI) and clinical outcome of arthroscopic rotator cuff repair.

METHODS

A comparative series of patients undergoing arthroscopic rotator cuff repair was studied. Two matched groups of patients (20 each) were included: rotator cuff repairs without PRPFM augmentation (group 1) and rotator cuff repairs augmented with 2 sutured platelet-rich plasma (PRP) constructs (group 2). A single-row cuff repair to the normal footprint without tension or marrow vents was performed by a single surgeon. Postoperative rehabilitation was held constant. Postoperative MRI scans were used to evaluate rotator cuff healing. Outcome measures included American Shoulder and Elbow Surgeons, Rowe, Single Assessment Numeric Evaluation, Simple Shoulder Test, and Constant scores.

RESULTS

We followed up 40 patients (2 matched groups with 20 patients each) with a mean age of 57 years (range, 44 to 69 years) for a mean of 31 months (range, 24 to 44 months). Postoperative MRI studies showed persistent full-thickness tendon defects in 60% of controls (12 of 20) and 30% of PRPFM-augmented repairs (6 of 20) (P = .03). Of the control group tears measuring less than 3 cm in anteroposterior length, 50% (7 of 14) healed fully, whereas 86% of the PRPFM group tears measuring less than 3 cm in anteroposterior length (12 of 14) healed fully (P < .05). There was no significant difference between groups 1 and 2 in terms of American Shoulder and Elbow Surgeons (94.7 and 95.7, respectively; P = .35), Single Assessment Numeric Evaluation (93.7 and 94.5, respectively; P = .37), Simple Shoulder Test (11.4 and 11.3, respectively; P = .41), and Constant (84.7 and 88.1, respectively; P = .19) scores. The Rowe scores (84.8 and 94.9, respectively; P = .03) were statistically different.

CONCLUSIONS

The addition of 2 PRPFM constructs sutured into a primary rotator cuff tendon repair resulted in lower retear rates identified on MRI than repairs without the constructs. Other than the Rowe scores, there was no postoperative clinical difference by use of standard outcome measures.

LEVEL OF EVIDENCE

Level III, case-control study.

Biomechanical analysis of pullout strengths of rotator cuff and glenoid anchors: 2011 update

PURPOSE

To evaluate the biomechanical and design characteristics of newer suture anchors.

METHODS

Suture anchors were tested in fresh porcine metaphyseal cortex and cancellous troughs by use of an established protocol. A mechanical testing machine applied tensile loads parallel to the axis of insertion at 12.5 mm/s until failure, and mean anchor failure strengths were calculated. The mode of failure was recorded. Rotator cuff anchors tested included the Doubleplay and Opus SpeedScrew (ArthroCare Sports Medicine, Sunnyvale, CA); PEEK Intraline and PEEK Zip (Stryker, San Jose, CA); Paladin, SuperRevo FT, and CrossFT (ConMed Linvatec, Largo, FL); Piton (Tornier, Warsaw, IN); Ti Screw, ALLthread PEEK, LactoScrew, ALLthread Ti, and ALLthread PEEK knotless (Biomet Sports Medicine, Warsaw, IN). Glenoid anchors included the Gryphon BR P (DePuy-Mitek, Raynham, MA) and JuggerKnot 1.4 (Biomet Sports Medicine).

RESULTS

Mean cortical failure loads for cuff anchors were as follows: Doubleplay 5.0, 279 N; Doubleplay 6.5, 338 N; Opus SpeedScrew 5.5, 356 N; Opus SpeedScrew 6.5, 336 N; PEEK Intraline 5.5, 263 N; PEEK Intraline 6.5, 344 N; PEEK Zip 5.5, 435 N; PEEK Zip 6.5, 502 N; Paladin 5.0, 500 N; Paladin 6.5, 521 N; SuperRevo FT, 496 N; CrossFT, 569 N; Piton, 379 N; Ti Screw 5.0, 457 N; Ti Screw 6.5, 443 N; ALLthread PEEK 5.5, 476 N; LactoScrew 5.5, 403 N; ALLthread Ti 5.0, 526 N; ALLthread Ti 6.5, 653 N; and ALLthread PEEK knotless, 441 N). Mean cortical failure loads for glenoid anchors were 161 N for Gryphon BR P and 239 N for JuggerKnot 1.4. Mean cancellous bone failure loads for cuff anchors were Doubleplay 5.0, 263 N; Doubleplay 6.5, 340 N; Opus SpeedScrew 5.5, 356 N; Opus SpeedScrew 6.5, 344 N; PEEK Intraline 5.5, 274 N; PEEK Intraline 6.5, 327 N; PEEK Zip 5.5, 401 N; PEEK Zip 6.5, 396 N; Paladin 5.0, 427 N; Paladin 6.5, 491 N; SuperRevo FT, 483 N; CrossFT, 547 N; Piton, 365 N; Ti Screw 5.0, 420 N; Ti Screw 6.5, 448 N; ALLthread PEEK 5.5, 475 N; LactoScrew 5.5, 435 N; ALLthread Ti 5.0, 512 N; ALLthread Ti 6.5, 612 N; and ALLthread PEEK knotless, 466 N). Mean cancellous failure loads for glenoid anchors were 117 N for Gryphon BR P and 194 N for JuggerKnot 1.4. None of the anchors had pullout as the predominant failure mode. Eyelet failure was the predominant failure mode for Doubleplay, Opus SpeedScrew, PEEK Intraline, Gryphon BR P, ALLthread Ti 6.5, ALLthread PEEK 5.5, and LactoScrew.

CONCLUSIONS

Failure load was not dependent on anchor location (cancellous or cortical bone) (P = .58) but was dependent on anchor type (cuff anchor or glenoid anchor) (P < .001).

CLINICAL RELEVANCE

Whereas larger fully threaded screw anchors designed for rotator cuff repair showed higher failure strengths than smaller non-screw anchors designed for glenoid repairs (P < .05), the larger version of a screw anchor for a cuff repair did not provide a statistically greater failure load than the smaller screw anchor.

Long-term degradation of a poly-lactide co-glycolide/β-tricalcium phosphate biocomposite interference screw

PURPOSE

To evaluate the long-term in vivo degradation of biodegradable interference screws made of poly-L-lactide co-glycolide (poly-L-lactic acid [PLLA]/polyglycolic acid [PGA]) and β-tricalcium phosphate (β-TCP).

METHODS

To study in vivo the biological behavior of a PLLA/PGA/β-TCP biocomposite screw (Milagro; DePuy Mitek, Raynham, MA), an institutional review board-approved program using anterior cruciate ligament (ACL) interference fixation screws was initiated in 2005. Thirteen patients who had bone-patellar tendon-bone ACL reconstruction fixed at both the femur and tibia with PLLA/PGA/β-TCP screws at least 24 months earlier were evaluated by physical, radiographic, and computed tomography (CT) evaluations. Lysholm, Tegner, Cincinnati, and International Knee Documentation Committee scores were also obtained. Radiographs and CT scans of the operated knee were obtained. CT scan data measured in Hounsfield units (HU) evaluated the material density at the screw and bone plug sites. Soft-tissue and cancellous and cortical bone site readings were also taken. Osteoconductivity scores were determined at the screw sites by use of an ossification quality score (range, 1 to 4).

RESULTS

Eleven men and two women were evaluated at a mean of 38 months after surgery (range, 24 to 49 months). CT scans and radiographs showed the bone plug fused to the tunnel wall with no PLLA/PGA/β-TCP screw remaining. The screws were replaced with material that was calcified and non-trabecular. Osteoconductivity was present in 21 of 26 tunnels (81%) and complete (type 4 ossification) in 5 of 26 (19%). Mean screw site densities (femoral, 159 HU; tibial, 157 HU) were not different from the mean cancellous bone density (femoral, 146 HU; tibial, 140 HU). No positive pivot-shift tests were found. Lysholm, Tegner, and Cincinnati scores improved from 44, 3.7, and 37 preoperatively to 93, 6, and 87 at follow-up, respectively. The mean KT arthrometer (MEDmetric, San Diego, CA) difference was 0.8 mm.

CONCLUSIONS

The PLLA/PGA/β-TCP interference screw completely degraded, and no remnant was present 3 years after implantation for a bone-patellar tendon-bone graft ACL reconstruction. Osteoconductivity was confirmed in 21 of 26 screw sites (81%) and completely filled the site in 5 of 26 (19%). The PLLA/PGA/β-TCP biocomposite interference screw is osteoconductive.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

A computed tomography scan assessment of synthetic multiphase polymer scaffolds used for osteochondral defect repair

PURPOSE

To evaluate the radiographic response of a synthetic multiphase implant at various intervals after implantation and assess the nature of bone ingrowth into the implant location.

METHODS

Patients undergoing autologous osteochondral transplantation for full-thickness condylar defects with the donor sites filled by use of a synthetic implant were evaluated by computed tomography (CT) scan for the density at both donor and recipient sites. Hounsfield unit (HU) readings were obtained at the synthetic implant, transplanted autograft plug, soft-tissue, cancellous bone, and cortical bone sites. The implant site material was graded by an established ossification quality score (range, 1 to 4).

RESULTS

Nine patients underwent CT scans at intervals ranging from 2 to 63 months after surgery. This sequence of images tracked the potential development of bone ingrowth activity. Postoperative imaging confirmed complete autograft bone plug healing. The synthetic implant site CT scans showed a drop in density from 84 HU at 4 months to 19 HU by 13 months (fibrous scar density). The ossification quality score for all synthetic implants was 1 (tract filled with soft-tissue density) instead of 4 (cancellous bone). The transplanted autograft plug densities were consistent with and completely incorporated into the adjacent cancellous bone.

CONCLUSIONS

The synthetic multiphase implant showed no evidence of bone ingrowth, osteoconductivity, or ossification. The implant density declined over time to that of fibrous scar. This synthetic plug does not provide subchondral structural support for any tissue that grows over it. This study does not support the use of this implant for the primary repair of articular cartilage lesions.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Comparative testing by cyclic loading of rotator cuff suture anchors containing multiple high-strength sutures

PURPOSE

To compare isolated medial-row with isolated lateral-row anchor performance by use of cyclic loading followed by destructive testing in an in vitro cadaveric model.

METHODS

Using 16 human cadaveric humeri without tendons, we rotated 4 medial-row (Bio-Corkscrew FT [Arthrex, Naples FL], CrossFT PK [ConMed Linvatec, Largo, FL], TwinFix PK FT [Smith & Nephew Endoscopy, Andover, MA], and Healix PK [DePuy Mitek, Raynham, MA]) and 4 lateral-row (PopLok PK [ConMed Linvatec], PEEK [polyetheretherketone] PushLock [Arthrex], Footprint PEEK [Smith & Nephew Endoscopy], and Versalok [DePuy Mitek]) anchors among different medial (articular cartilage edge) and lateral greater tuberosity sites (anterior, central, posterior). All medial anchors were inserted into the humeral head at an angle no greater than 45 degrees . All lateral anchors were inserted "over the top," nearly planar to the superior humeral surface. After preloading, the constructs were cycled 500 times from 10 to 60 N at 1 Hz with the loads applied to the accompanying sutures. Those constructs surviving cycling were destructively tested. Cyclic displacement, ultimate load, and failure mode were recorded.

RESULTS

In this laboratory setting, most displacement occurred in the first 100 cycles except for the Footprint anchor. Lateral-row anchors had greater mean displacements (2.6 mm) than medial-row anchors (1.2 mm) at 100 cycles and between 100 and 500 cycles (1.8 mm v 0.75 mm). Lateral-row anchors also had more total displacement (4.4 mm) than medial-row anchors (1.9 mm). A 5-mm displacement gap, defined as failure, was not seen in the Bio-Corkscrew FT, TwinFix PK FT, and Versalok anchors. Ultimate failure loads ranged from 163 N (Footprint) to 308 N (Versalok) (P < .05). The principal failure mode was anchor pullout, followed by eyelet breakage. Medial-row eyelet failures only occurred after 500 cycles at loads higher than each anchor's mean failure load. Eyelet failure for lateral-row anchors occurred before 500 cycles and at failure loads lower than each anchor's mean.

CONCLUSIONS

Lateral row anchors benefit from medial row anchors for their security, and because of design differences demonstrate more displacement. When lateral-row anchors fail at the eyelet, it is at lower failure loads, while if medial-row anchors fail at the eyelet, it is at higher loads.

CLINICAL RELEVANCE

Anchors designed to function as lateral-row fixation provide fixation strength inferior to that of medial-row anchors and are more likely to be subject to suture slippage.

Biomechanical advantages of triple-loaded suture anchors compared with double-row rotator cuff repairs

PURPOSE

To evaluate the strength and suture-tendon interface security of various suture anchors triply and doubly loaded with ultrahigh-molecular weight polyethylene-containing sutures and to evaluate the relative effectiveness of placing these anchors in a single-row or double-row arrangement by cyclic loading and then destructive testing.

METHODS

The infraspinatus muscle was reattached to the original humeral footprint by use of 1 of 5 different repair patterns in 40 bovine shoulders. Two single-row repairs and three double-row repairs were tested. High-strength sutures were used for all repairs. Five groups were studied: group 1, 2 triple-loaded screw suture anchors in a single row with simple stitches; group 2, 2 triple-loaded screw anchors in a single row with simple stitches over a fourth suture passed perpendicularly ("rip-stop" stitch); group 3, 2 medial and 2 lateral screw anchors with a single vertical mattress stitch passed from the medial anchors and 2 simple stitches passed from the lateral anchors; group 4, 2 medial double-loaded screw anchors tied in 2 mattress stitches and 2 push-in lateral anchors capturing the medial sutures in a "crisscross" spanning stitch; and group 5, 2 medial double-loaded screw anchors tied in 2 mattress stitches and 2 push-in lateral anchors creating a "suture-bridge" stitch. The specimens were cycled between 10 and 180 N at 1.0 Hz for 3,500 cycles or until failure. Endpoints were cyclic loading displacement (5 and 10 mm), total displacement, and ultimate failure load.

RESULTS

A single row of triply loaded anchors was more resistant to stretching to a 5- and 10-mm gap than the double-row repairs with or without the addition of a rip-stop suture (P < .05). The addition of a rip-stop stitch made the repair more resistant to gap formation than a double row repair (P < .05). The crisscross double row created by 2 medial double-loaded suture anchors and 2 lateral push-in anchors stretched more than any other group (P < .05).

CONCLUSIONS

Double-row repairs with either crossing sutures or 4 separate anchor points were more likely to fail (5- or 10-mm gap) than a single-row repair loaded with 3 simple sutures.

CLINICAL RELEVANCE

The triple-loaded anchors with ultrahigh-molecular weight polyethylene-containing sutures placed in a single row were more resistant to stretching than the double-row groups.

Glenohumeral chondrolysis after shoulder arthroscopy associated with continuous bupivacaine infusion

PURPOSE

To determine the incidence of glenohumeral chondrolysis associated with the use of a continuous-infusion device in shoulder arthroscopy.

METHODS

A consecutive series of patients undergoing arthroscopic glenohumeral surgery with a postoperative continuous-infusion pump inserted into either the glenohumeral joint or subacromial space were evaluated for chondrolysis. Two pump types were used: group 1 received 100 mL of 0.5% bupivacaine without epinephrine infused at 2.08 mL/h, and group 2 received 270 mL of 0.5% bupivacaine without epinephrine infused at 4.16 mL/h.

RESULTS

We followed up 65 patients at a mean of 40 months. Of these, 29 had glenohumeral catheters (13 in group 1 and 16 in group 2) and 36 had subacromial catheters (19 in group 1 and 17 in group 2). The overall postoperative Constant, American Shoulder and Elbow Surgeons, Rowe, Single Assessment Numeric Evaluation, and Simple Shoulder Test scores were 84, 87, 77, 86, and 10, respectively, in those with glenohumeral catheters and 93, 94, 95, 89, and 11, respectively, in those with subacromial catheters. Three glenohumeral catheter patients were diagnosed with chondrolysis, all in group 2.

CONCLUSIONS

Chondrolysis developed in 3 of 16 patients (19%) with glenohumeral joint infusion of 0.5% bupivacaine without epinephrine at 4.16 mL/h for 65 hours. No patient using a 2.08-mL/h reservoir for 48 hours into the glenohumeral joint and no patient with a subacromial infusion device had chondrolysis. Clinical symptoms and radiographic evidence of chondrolysis developed before 12 months after surgery.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Biomechanical testing of commercially available soft-tissue augmentation materials

PURPOSE

To evaluate several physical properties and physical dimensions of commercially available soft-tissue augmentation devices.

METHODS

After 2 x 5-cm strips of several graft materials were hydrated, load elongation, cyclic and permanent displacement, percent elastic displacement, tensile modulus, stiffness, and ultimate load-to-failure strength were determined. With a 5-N preload, 30 cyclic loads between 5 N and 50 N were applied at 12.5 mm/s followed by destructive testing. A vertical stitch suture retention test was also performed.

RESULTS

SportMesh (Biomet Sports Medicine, Warsaw, IN) displaced more than any other material (P < .001). GraftJacket MaxForce Extreme (Wright Medical Technology, Arlington, TN) and Allopatch HD 2 (Musculoskeletal Tissue Foundation, Edison, NJ) displaced more than RC Allograft (Arthrex, Naples, FL) (P < .05). Percent elastic deformation did not differ among these materials. OrthAdapt (Pegasus Biologics, Irvine CA) had a higher tensile modulus than RC Allograft, SportMesh, and Allopatch HD 2 (P < .001). Allopatch HD 1 and GraftJacket MaxForce Extreme had a higher tensile modulus than RC Allograft and SportMesh. GraftJacket MaxForce had a higher tensile modulus than RC Allograft (P < .001). GraftJacket MaxForce Extreme stiffness was greater than that of OrthAdapt and SportMesh (P < .001), and GraftJacket MaxForce, RC Allograft, Allopatch HD 1, and Allopatch HD 2 stiffness was greater than that of SportMesh (P < .001). The ultimate strength of GraftJacket MaxForce, GraftJacket MaxForce Extreme, Allopatch HD 1, and Allopatch HD 2 was greater than that of OrthAdapt and SportMesh (P < .05). Acellular human collagen matrix grafts (GraftJacket and Allopatch HD) showed greater suture retention strength than RC Allograft and SportMesh, which were both stronger than OrthAdapt (P < .05).

CONCLUSIONS

The acellular human collagen matrix grafts showed greater elongation than the cuff tendon allograft (RC Allograft), although SportMesh elongated more than all other materials tested. The tensile modulus, which is "normalized" to eliminate differences in the size of the tissue tested, was greater for the OrthAdapt material than for GraftJacket, Allopatch, RC Allograft, and SportMesh. Suture retention strength was greatest in the acellular human collagen matrix grafts (GraftJacket and Allopatch), whereas both SportMesh and RC Allograft had greater suture retention strength than OrthAdapt.

CLINICAL RELEVANCE

Acellular human collagen matrix grafts (GraftJacket and Allopatch) are stronger after cyclic loading than SportMesh and OrthAdapt and show greater stiffness.

Biomechanical testing of new meniscal repair techniques containing ultra high-molecular weight polyethylene suture

PURPOSE

To evaluate the biomechanical characteristics of current meniscal repair techniques containing ultra high-molecular weight polyethylene (UHMWPE) suture with and without cyclic loading.

METHODS

Vertical longitudinal cuts made in porcine menisci were secured with a single repair device. Noncycled and cycled (500 cycles) biomechanical tests were performed on the following groups: group 1, No. 2-0 Mersilene vertical suture (Ethicon, Somerville, NJ); group 2, No. 2-0 Orthocord vertical suture (DePuy Mitek, Westwood, MA); group 3, No. 0 Ultrabraid vertical suture (Smith & Nephew Endoscopy, Andover, MA); group 4, No. 2-0 FiberWire vertical suture (Arthrex, Naples, FL); group 5, vertically oriented mattress suture by use of an Ultra FasT-Fix device (Smith & Nephew Endoscopy) with No. 0 Ultrabraid; group 6, vertically oriented mattress suture by use of a RapidLoc A2 device (DePuy Mitek) with No. 2-0 Orthocord suture; group 7, vertically oriented stitch by use of a MaxFire device with MaxBraid PE suture (Biomet Sports Medicine, Warsaw, IN); and group 8, an obliquely oriented stitch of No. 0 UHMWPE suture inserted by use of a CrossFix device (Cayenne Medical, Scottsdale, AZ). Endpoints were failure loads, failure modes, stiffness, and cyclic displacement.

RESULTS

Mean single-pull loads were calculated for Ultra FasT-Fix (121 N), FiberWire (110 N), MaxFire (130 N), Mersilene (84 N), Orthocord (124 N), RapidLoc A2 (86 N), CrossFix (77 N), and Ultrabraid (109 N). After 500 cyclic loads, the Orthocord (222 N) repair was stronger than the others: Ultra FasT-Fix (110 N), FiberWire (117 N), MaxFire (132 N), Mersilene (89 N), RapidLoc A2 (108 N), CrossFix (95 N), and Ultrabraid (126 N) (P < .05). Ultrabraid suture showed significantly more elongation over 500 cycles than the other repairs (P < .05). The principal failure mode associated with the single destructive pull (suture breakage) changed to pulling through the meniscus after cyclic loading for most devices. Knot slippage or device failure was seldom observed as the failure mode with these techniques.

CONCLUSIONS

Self-adjusting, UHMWPE suture-containing meniscal repair devices (Ultra FasT-Fix, RapidLoc A2, and MaxFire) were comparable to the isolated UHMWPE-containing suture repairs on single-failure load testing. UHMWPE-containing suture repairs are stronger than braided polyester suture repairs, but pure UHMWPE suture (Ultrabraid) elongated more during cycling. Orthocord suture is significantly stronger than the other meniscal repair techniques after cyclic loading (P < .05).

CLINICAL RELEVANCE

Meniscal repair techniques using UHMWPE containing sutures provide greater strength than earlier generations of meniscal repair techniques.

Cyclic load and failure behavior of arthroscopic knots and high strength sutures

PURPOSE

To compare the biomechanical performance of several different sutures by evaluating knot security and load to failure strength using different arthroscopic knots.

METHODS

Eight different No. 2 sutures (Ethibond [Ethicon, Somerville, NJ], FiberWire [Arthrex, Naples, FL], Orthocord [DePuy-Mitek, Norwood, MA], Hi-Fi [ConMed Linvatec, Largo, FL], Ultrabraid [Smith & Nephew, Andover, MA], ForceFiber [Stryker Endoscopy, San Jose, CA], MagnumWire [ArthroCare, Sunnyvale, CA], and MaxBraid PE [Arthrotek, Warsaw, IN]) were tied arthroscopically into standardized loops using 6 different knots (Weston, Tennessee slider, Duncan, SMC, Revo, and San Diego knot) 10 times each. The suture loops were pretensioned to 10N, cycled between 10N and 45N for 1,000 cycles, and loaded to failure. The failure load for each suture, each knot, and slippage trend during cyclic loading was recorded.

RESULTS

The Revo and SMC knots (group A) were stronger than the Tennessee and San Diego knots (group B), which were stronger than the Weston knot, which was stronger than the Duncan loop (P < .05). This pattern also coincided with the loads at which these knots slipped. Evaluating the sutures showed that Ethibond had lower failure loads than all other sutures and FiberWire showed statistically higher loads (P < .05). Duncan loops (97.5%) and Weston knots (86.3%) slipped more than other knots (P < .001), while the SMC and Revo knots slipped least. Ethibond sutures were least likely to slip.

CONCLUSIONS

The Duncan loop and Weston knot were more likely to slip than all other knots, and caution should be exercised when tying them with high-strength sutures. The Revo, Tennessee slider, San Diego, and SMC knots were least likely to slip (P < .001).

CLINICAL RELEVANCE

While stronger than braided polyester sutures, newer sutures containing ultra-high molecular weight polyethylene have a greater tendency to slip. Backing up knots with 4 reversed half hitches with switched posts does not guarantee knot security.

FasT-Fix meniscal repair: mid-term results

PURPOSE

The purpose of this study was to evaluate the clinical success of the FasT-Fix meniscal repair device (Smith & Nephew Endoscopy, Andover, MA) associated with an accelerated rehabilitation program.

METHODS

A prospectively collected consecutive series of meniscal repairs performed with the FasT-Fix device was studied. The Lysholm, Tegner, Cincinnati, and International Knee Documentation Committee activity scores, along with the clinical examination findings and adverse events, were recorded for all patients. Associated procedures were recorded. An accelerated postoperative rehabilitation program was followed, independent of concurrent anterior cruciate ligament surgery.

RESULTS

Forty-one meniscal repairs were performed, with an average follow-up of 30.7 months (range, 12 to 58 months). Twenty-nine of 41 repairs were performed in conjunction with anterior cruciate ligment reconstruction. The other repairs were in stable knees. There were 26 medial and 15 lateral meniscus repairs. Both menisci were repaired in 5 knees. Repeat arthroscopies were performed for 12 repairs and 7 (17%) were found to have failed. The preoperative and postoperative Lysholm, Tegner, Cincinnati, and International Knee Documentation Committee activity scores were 47.3 and 87.4, 3.4 and 7.2, 38.7 and 82.8, and 2.3 and 3.4, respectively.

CONCLUSIONS

The FasT-Fix meniscal repair associated with an accelerated rehabilitation program resulted in clinically effective meniscal repair in 83% at the time of follow-up. Clinical outcome measures all improved.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Postoperative pain control after shoulder arthroscopy

Successful postoperative pain management after arthroscopic shoulder surgery allows patients to go home earlier, decreases the potential for hospital readmission, and facilitates rehabilitation. Optimal pain control considers the physiological and psychological states of the patient, the resulting alterations due to the surgery, and the technical and economic resources available during recovery. A comprehensive approach to pain control should include preoperative, intraoperative, and postoperative efforts. Efforts at postoperative pain reduction should begin preoperatively with the establishment of an excellent patient/physician relationship. Preoperative analgesia should be administered. Intraoperative efforts should include the administration of anesthetic medication intra-articularly. Postoperative management should include sleep medication, continuous cold-flow therapy, oral analgesics, and, if necessary, the use of narcotics.

Suture anchor materials, eyelets, and designs: update 2008

PURPOSE

Our purpose was to evaluate recently introduced sutures and suture anchors for single pull load to failure strength and failure mode.

METHODS

Suture anchors were tested in fresh porcine metaphyseal cortex and cancellous troughs using an established protocol. An Instron machine applied tensile loads parallel to the axis of insertion at a rate of 12.5 mm per second until failure and mean anchor failure strengths were calculated. The mode of failure was recorded (anchor pullout, suture eyelet cut out, or suture failure). Anchors tested included the Kinsa, Kinsa RC, BioRaptor 2.3 PK, TwinFix PK FT 5.5 and 6.5, BioCleat, Healix Peek, VersaLok, BioKnotless, BioKnotless BR, Corkscrew FT III, SwiveLock C, and PEEK SutureTak.

RESULTS

The mean cortical failure loads were as follows: Kinsa (219 N), Kinsa RC (222 N), BioRaptor 2.3 PK (172 N), TwinFix PK FT 5.5 (491 N) and 6.5 (503 N), BioCleat (218 N), Healix Peek (407 N), VersaLok (376 N), BioKnotless (249 N), BioKnotless BR (265 N), Corkscrew FT III (386 N), SwiveLock C (712 N), and PEEK SutureTak (168 N). Pullout was the predominant failure mode for the VersaLok, BioKnotless, BioKnotless BR, and BioRaptor 2.3PK anchors. Eyelet failure was the predominant failure mode for the Kinsa, Kinsa RC, BioCleat, Healix Peek, Corkscrew FT III, SwiveLock C, and PEEK SutureTak.

CONCLUSIONS

The newer anchors showed markedly increased load to failure strengths. Two or more high-strength sutures are commonly used as well as new anchor materials (PEEK and Biocryl Rapide), new eyelet designs, and the increased use of a "knotless" concept.

CLINICAL RELEVANCE

An anchor which fails principally by pull out at a low load to failure is at risk for creating an intra-articular loose body.

Insertion force of articular cartilage transplantation systems

This study compared the insertion force, plug harvest consistency, and recipient site creation consistency of 4 different articular cartilage transplantation systems (COR, OATS, Mosaicplasty, and New COR2) during plug insertion using a single-impaction technique. Maximum insertion forces fell into 3 statistically different groups: group 1, OATS 8-mm (238 N) and 10-mm (215 N) systems; group 2, COR 6-mm (133 N) and 8-mm (176 N), Mosaicplasty, 6.5-mm (147 N) and 8.5-mm (134 N), and OATS 6-mm (137 N) systems; and group 3, New COR2 6-mm (68 N), 8-mm (55 N), and 10-mm (54 N) systems (P < or = .05). OATS compaction pressures were 172 N (6 mm), 353 N (8 mm), and 550 N (10 mm). COR, New COR2, and Mosaicplasty donor plugs were created consistently, but the Mosaicplasty system required toggling. OATS plugs had inconsistent lengths but required no toggling. Insertion forces with the New COR2 system were statistically the lowest. Compaction significantly increased surface forces.

Long-term absorption of beta-tricalcium phosphate poly-L-lactic acid interference screws

PURPOSE

The purpose of this study was to evaluate the long-term in vivo degradation of biodegradable interference screws made of poly-L-lactic acid (PLLA) and beta-tricalcium phosphate (beta-TCP).

METHODS

Twenty patients undergoing patellar tendon autograft anterior cruciate ligament reconstruction fixed at both the femur and tibia with beta-TCP-PLLA screws at least 44 months earlier were evaluated by physical, radiographic, and computed tomography (CT) evaluations. This study was approved by the institutional review board. Lysholm, Tegner, Cincinnati, and International Knee Documentation Committee scores were also obtained. CT data were measured in Hounsfield units.

RESULTS

We evaluated 13 male and 7 female patients at a mean of 50 months after surgery (range, 44 to 56 months). CT scans and radiographs showed the bone plug fused to the tunnel wall with no beta-TCP-PLLA screw remaining. The screws were replaced with clearly calcified non-trabecular material, denser than soft tissue. Osteoconductivity was present in 75% of the tunnels and complete in 10%. No positive pivot-shift tests were found. Lysholm, Tegner, and Cincinnati scores improved from 60.4, 3.7, and 53.3, respectively, preoperatively to 90.8, 5.8, and 86.4, respectively, at follow-up. The mean side-to-side difference determined by use of the KT arthrometer (MEDmetric, San Diego, CA) was 0.4 mm.

CONCLUSIONS

The beta-TCP-PLLA interference screw (Bilok; ArthroCare, Sunnyvale, CA) completely degraded, and no remnant was present 4 years after insertion. Osteoconductivity was confirmed by CT scans at 75% of the screw sites and completely filled the site in 10%. The addition of beta-TCP to PLLA results in a biocomposite interference screw that is osteoconductive.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Meniscal tear biomechanics: loads across meniscal tears in human cadaveric knees

This study examined the forces during motion across human meniscal tears. Longitudinal cuts were created in 6 human cadaveric knees at the red-white junction of the medial and lateral menisci into which a pressure transducer was placed. Pressure data were gathered with the knees at neutral, internal rotation, and external rotation and matched to knee flexion. The meniscal cuts were compressed throughout the range of motion. No distraction pressures were observed. Therefore, meniscal tear displacement does not occur with knee motion and a meniscal repair device load-to-failure strength may be less important than the device's ability to accurately reduce a meniscal tear and avoid shear stress.

A biomechanical study of Achilles tendon repair augmentation using GraftJacket matrix

BACKGROUND

Ruptured Achilles tendons benefit from primary repair by decreasing re-rupture rates and allowing earlier range of motion. A stronger repair might allow for more aggressive rehabilitation decreasing postoperative stiffness, calf atrophy, and repair site gapping. The hypothesis of this study was that human dermal allograft augmentation of an Achilles repair would significantly increase repair strength and stiffness. This study evaluated strength and stiffness of an Achilles tendon repair augmented with a human dermal allograft (GraftJacket).

MATERIALS AND METHODS

Eight matched pairs of human cadaver legs were used. Simulated Achilles tendon ruptures were created 4 cm proximal to the calcaneal insertion. All tendons were repaired with a Krackow locking loop stitch. One of each matched pair was augmented with GraftJacket. Each construct was pre-loaded at 10 N and cyclically loaded (20 cycles) from 2 N to 30 N at a rate of 5 N/sec on an Instron machine. This was followed by testing to failure at a displacement rate of 6 mm/sec.

RESULTS

The ultimate failure load in the control group was 217 N +/- 31 compared to 455 N +/- 76.5 in the GraftJacket group (p < 0.001). The mean stiffness in the control group was 4.3 +/- 0.83 N/mm which was significantly less than the 12.99 +/- 5.34; N/mm in the GraftJacket group (p = 0.002).

CONCLUSION

The augmentation of an Achilles tendon repair with GraftJacket significantly increased repair strength and stiffness.

CLINICAL SIGNIFICANCE

These findings suggest that a GraftJacket augmented Achilles tendon repair could acutely withstand a more aggressive rehabilitation program, potentially decreasing ankle stiffness and allowing earlier return to full activities.

Percutaneous arthroscopic release of the suprascapular nerve

Suprascapular nerve release is often performed for entrapment syndromes and to release pressure on the nerve associated with arthroscopic rotator cuff repair. Previous descriptions use basket forceps or scissors through a separate portal. This report describes an arthroscopic technique inserting a 14-gauge needle percutaneously in the superior suprascapular area while viewing through a standard posterior portal. A shaver through the lateral portal clears the acromion and distal clavicle of soft tissue and exposes the coracoclavicular ligaments. The medial border of the coracoclavicular ligaments (conoid ligament) is identified and then followed inferiorly to its coracoid attachment. The shaver removes the adipose tissue for better visualization and depresses and retracts the supraspinatus muscle. The transverse scapular ligament is located with the suprascapular artery coursing across its superior surface. A 14-gauge beveled needle is inserted in the "soft spot" medial to the junction of the scapular spine and clavicle. This insertion site is located approximately 7 cm medial to the lateral border of the acromion. The transverse scapular ligament is horizontal at this location and can be divided with the needle tip via an anterior-posterior sweeping motion, avoiding the suprascapular artery and decompressing the suprascapular nerve.