Modification of side-locking loop suture technique using an antislip knot for repair of Achilles tendon rupture.

The 2-strand side-locking loop suture technique provides high tensile strength and stiffness immediately after surgery, and good clinical results have been reported in the treatment of Achilles tendon rupture. However, it is assumed that major differences exist among surgeons with regard to the optimal tension of the side-locking loop suture. We report a detailed technique to ensure application of a standard tension with the use of the side-locking loop suture in the clinical setting.

Bone screws have advantages in repair of experimental osteochondral fragments.

BACKGROUND: Cartilage defects are created on intraarticular osteochondral fragments at the entrance holes of fixation devices when these fragments are fixed to the original sites. Conventional fixation devices hinder repair of these defects and there is a latent risk of secondary osteoarthritis. We therefore developed a novel fixation device system consisting of bone screws made of cortical bone for osteochondral fragments to improve repair of these surface defects. QUESTIONS/PURPOSES: We asked whether bone screws had advantages over poly-L-lactic acid (PLLA) screws in terms of (1) gross assessment of the surface, (2) volume and histologic quality of the repair tissue, and (3) biomechanical assessment of the tissue stiffness. METHODS: We examined gross morphology, microCT, histology, and stiffness of the repaired tissue with PLLA (n = 32) and bone (n = 32) screws in a rabbit model of osteochondral fracture, compared with normal controls (n = 16). RESULTS: Gross morphology and histology revealed better quality with bone screws than with PLLA screws. Mean repaired volumes in microCT were 70.6% ± 14% with bone screws and 50.3% ± 15% with PLLA screws. Average stiffness values for PLLA screws, bone screws, and normal cartilage were 1.67 ± 0.54 N/mm, 2.63 ± 0.42 N/mm, and 3.15 ± 0.49 N/mm, respectively. CONCLUSIONS: Our results show better repaired tissue was observed for quality and quantity when chondral fractures were treated with bone screws than when treated with PLLA screws. CLINICAL RELEVANCE: Bone screws made of cortical bone may have applications in clinical situations for the fixation of intraarticular osteochondral fragments.

Increased antibiotic release from a bone cement containing bacterial cellulose.

BACKGROUND: Major disadvantages of antibiotic bone cements include limited drug release and reduced strength resulting from the addition of high doses of antibiotics. Bacterial cellulose, a three-dimensional hydrophilic mesh, may retain antibiotics and release them gradually. We hypothesized that the addition of cellulose to antibiotic bone cement would improve mechanical strength and antibiotic release. QUESTIONS/PURPOSES: We therefore examined the mechanical strength and antibiotic release of cellulose antibiotic cement. METHODS: A high dose of antibiotics (5 g per 40 g cement powder) was incorporated into bacterial cellulose and then mixed with bone cement. We compared the compression strength, fracture toughness, fatigue life, and elution kinetics of this formulation with those of plain cement and a traditional antibiotic cement. RESULTS: The average values for compression strength, fracture toughness, and fatigue life of the cellulose antibiotic cement were 97%, 97%, and 78% of the values obtained for plain cement, respectively. The corresponding values for the traditional antibiotic cement were 79%, 82%, and 17%, respectively. The cumulative elution over 35 days was 129% greater from the cellulose antibiotic cement than from the traditional antibiotic cement. CONCLUSIONS: With a high dose of antibiotics, incorporating cellulose into the bone cement prevented compression and fracture fragility, improved fatigue life, and increased antibiotic elution. CLINICAL RELEVANCE: Antibiotic cements containing cellulose may have applications in clinical situations that require high levels of antibiotic release and preservation of the mechanical properties of the cement.

Nonunion in proximal phalanx of great toe treated by grafting with precisely processed autologous bone PEG.

We report a rare case of nonunion in the proximal phalanx of the great toe treated by grafting with a precisely processed autologous bone peg. The concept of this surgical method was to fix the nonunion of the proximal phalanx of the great toe using press-fit fixation and a bone peg precisely formed to fit the medullary cavity similar to an intramedullary nail. We believe that our new technique is a viable alternative for the treatment of phalanx fractures or nonunions requiring bone grafts.

Measurement characteristics of a force-displacement curve for chronic patellar instability.

OBJECTIVE: The clinical diagnosis of patellar instability is subjective, depending on the patient's apprehension. We hypothesized that a subjective diagnosis could be supported by a numerical evaluation of the slope, or compliance, of the early phase of a force-displacement curve. DESIGN: Cross-sectional control group comparison. SETTING: A university-based sports clinic. PARTICIPANTS: Healthy volunteers (n = 21; 16-40 years old) and patients (n = 21; 15-34 years old) who had a clearly definable diagnosis of unilateral dislocation, followed by chronic anterior knee pain, and positive apprehension signs for more than 6 months, without patella alta or abnormal limb alignment. INTERVENTION: Lateral displacement and reactive forces were measured with a Patella Stability Tester. MAIN OUTCOME MEASURES: Sensitivity in detecting injured knees was defined, with the 95% confidence interval of healthy subjects determined as the normal range. RESULTS: Compliance at 5 mm in displacement showed the highest reproducibility (plot difference of 4.7%) and the highest sensitivity (95%). Among injured knees, compliance was significantly correlated with the activity-related symptoms of the Kujala score (correlation coefficient, -0.61; P = 0.004). Compliance at 5 mm of displacement showed the highest sensitivity (95%) and significant correlation with the activity-related symptoms of the Kujala score among injured knees (coefficient of determination, 0.37; P = 0.004). CONCLUSIONS: It is a novel finding that early compliance at 5 mm of displacement showed a correlation with the subjective diagnosis and symptoms.

In vitro evaluation of allogeneic bone screws for use in internal fixation of transverse fractures created in proximal sesamoid bones obtained from equine cadavers.

OBJECTIVE: To evaluate effectiveness of allogeneic bone screws and pins for internal fixation of midbody transverse fractures of equine proximal sesamoid bones (PSBs) in vitro. SAMPLE POPULATION: 14 forelimbs from cadavers of 3-year-old Thoroughbreds. PROCEDURES: Allogeneic cortical bone fragments were collected from the limbs of a male Thoroughbred, and cortical bone screws were prepared from the tissue by use of a precision desktop microlathe programmed with the dimensions of a metal cortical bone screw. A midbody transverse osteotomy of each PSB was performed by use of a bone-shaping oscillating saw and repaired via 1 of 3 internal fixation techniques: 1 allogeneic bone screw with 1 allogeneic bone pin (type I; n = 6 PSBs), 2 allogeneic bone screws (type II; 8), or 1 stainless steel cortical bone screw (control repair; 6). Mechanical tension measurements were obtained by use of a commercially available materials testing system. RESULTS: Mean +/- SD tensile strength (TS) was 668.3 +/- 216.6 N for type I repairs, 854.4 +/- 253.2 N for type II repairs, and 1,150.0 +/- 451.7 N for control repairs. CONCLUSIONS AND CLINICAL RELEVANCE: Internal fixation of PSB fractures by the use of allogeneic bone screws and bone pins was successful. Although mean TS of control repairs with stainless steel cortical bone screws was greater than the mean TS of type I and type II repairs, the difference between type II and control repairs was not significant. Allogeneic screws may advance healing and result in fewer complications in a clinical setting.

Optimum predrilled hole size for bone screws used in osteochondral fixation: in vitro biomechanical study and clinical case.

BACKGROUND: Bone screws have a mechanical advantage over bone pegs for fixation of osteochondral fractures. The purpose of this study was to investigate predrilling methods to facilitate bone screw insertion. METHODS: The 162 bone screws (major diameter 3.0 mm; minor diameter 2.5 mm; length 10 mm) used were made from porcine tibial cortical bone. Metal screws of the same design were used as a control. The screws were inserted, without tapping, into predrilled holes of six different sizes (2.4-2.9 mm diameter; 80%-97% of the screw) made in cancellous bone harvested from porcine femoral condyle, and pullout strength was determined. The volumetric bone mineral densities of porcine bones were compared to those of human bones. In a clinical case, an osteochondral fracture of the patella was repaired using three autologous bone screws. RESULTS: Bone screws occasionally broke due to high insertion torque (108-158 N.mm); the incidences were 30% and 19% with the 80% and 83% sized holes, respectively. None of the screws inserted into holes of size >/= 87% broke, and their insertion torques never exceeded 100 N.mm. Metal screws were inserted without breakage regardless of hole size. Bone screws inserted into 80%-93% holes had the greatest pullout strengths (range 154-165 N), whereas 97% holes had a mean strength of 84 N. Metal screws had large pullout strengths when inserted into 80% and 83% holes (164 and 169 N, respectively). The mineral density of porcine bone was lower than that of human bone (1167 and 1357 mg/cm(3) for cortical bone and 193 and 269 mg/cm(3) for cancellous bone, respectively). In the clinical case, bone screws were inserted smoothly into 90% holes. CONCLUSIONS: The optimal size of predrilled holes for bone screws (87%-93%) differs from that for metal screws.

Effect of implant surface roughness on bone fixation: the differences between bone and metal pegs.

BACKGROUND: Pegs made from cortical bone are used to fix osteochondral fractures and osteochondral dissecans. This technique has many advantages, but it requires long-term immobilization. This study examined the effect of surface roughness on fixation with bone and metal pegs. METHODS: Pegs with either rough or smooth surfaces were made of cortical bone from Japanese black cattle or from stainless steel (SUS316L). The mean roughness of the rough surface was 15.0 microm, whereas that of the smooth surface was less than 0.6 microm. Pegs were inserted into holes made in the distal femurs of 34 rabbits. At the time of surgery and 14 days later, mechanical tests and micro-computed tomography were performed. RESULTS: At the time of surgery, although the push-out forces were less than 0.3 N, the rough surface had a higher value than the smooth surface (P = 0.0002). No difference was observed according to the material (P = 0.54). Fourteen days after surgery, no significant difference was detected in the push-out forces between bone pegs with rough and smooth surfaces (489.0 +/- 149.6 vs 478.3 +/- 134.4 N (mean +/- SD), respectively), but a marked difference was seen with the metal pegs (235.7 +/- 115.7 vs 2.2 +/- 1.6 N). The bone pegs with rough surfaces made contact with the recipient bone at the high points on the abraded surfaces. After the mechanical tests, the fusion was broken within the new bone for bone pegs with rough or smooth surfaces, but no breakage occurred at the junction of bone peg and new bone. CONCLUSION: The surface roughness of bone pegs has little effect on bone-to-bone fusion 2 weeks postoperatively, unlike the effect with metal pegs.

Flexor tendon repair using the two-strand side-locking loop technique to tolerate aggressive active mobilization immediately after surgery.

BACKGROUND: Early mobilization after tendon repair decreases adhesion formation and improves repair-site strength. We investigated whether the two-strand side-locking loop technique would tolerate aggressive active mobilization immediately after surgery. METHODS: Twelve flexor digitorum profundus tendons of the porcine forelimbs were sutured by the two-strand side-locking loop technique with a cross-stitch epitendinous repair (Group A), and by the 8-strand repair method with a simple running suture (Group B). Gaps and residual tensile strength after cyclic loadings of 3-50 N (for 10,000 rounds) were measured. FINDINGS: Gaps after cyclic loading in Group A were 0.5+/-0.3 and 1.2+/-0.8 mm while those in Group B were 3.5+/-0.8 and 5.2+/-1.2 mm at 3 and 50 N, respectively. In addition, the respective residual tensile strength of Groups A and B were 207.1+/-15.2 and 84.2+/-18.3N. INTERPRETATION: A combination of the two-strand side-locking loop technique with cross-stitch epitendinous repair served as the optimum suture method in establishing safe and early active mobilization without the aid of a specialized rehabilitation staff.

Optimum location of knot for tendon surgery in side-locking loop technique.

BACKGROUND: Although various tendon repair techniques have been reported to achieve stronger repair, suture failures tend to occur near the knot. We experimentally investigated whether the location of a single core suture knot affects the biomechanical properties of the repair. METHODS: Transected bovine tendons (male Japanese black cattle, 24 months old) of the medial gastrocnemius (9-11 x 14-16 mm in diameter) were sutured with the side-locking loop technique using a USP2-sized polyethylene and polyester multifilament suture or polyester multifilament suture. The knot was made using 7 simple square ties (a surgeon's knot plus 5 ties) at three locations; on the loop, between the tendon stumps, or between the loops burying the knot in a tendon slit using a scalpel. A cyclical loading protocol from 10N to 100N was used and the loading was repeated 10,000 times. FINDINGS: The gap was most decreased and the ultimate strength was most increased when the knot was located between the loops when using a polyethylene and polyester multifilament suture. Cross-sectional area of the tendon showed the ratio of the buried knot relative to the tendon was only 1.6-2.3%, and the polyethylene and polyester multifilament suture was very durable against frictional abrasion. INTERPRETATION: We found that the knot between the loops, buried in the bovine tendon provided the optimum results.

[The effect of non-steroidal anti-inflammatory drugs on upper gastrointestinal disorders in orthopaedic patients].

We investigated the effect of non-steroidal anti-inflammatory drugs (NSAIDs) on upper gastrointestinal(GI) disorders in orthopaedic patients. Among a total of 1,923 patients (946 men and 977 women, mean age: 53 years) who received NSAIDs, 486 patients (25%) experienced some adverse reactions including mild GI symptoms, 364 patients (19%) had gastric mucosal lesion, and 37 patients (2%) had gastric ulcer. The number of patients with upper GI disorders was significantly higher in patients aged 50 years or older, than those under 50 years. Irrespective of the kinds of NSAIDs applied, our results suggest an increased risk of adverse effect causing upper GI disorders in orthopaedic patients who are administered NSAIDs for a long-term.

Optimum combination of monolayer and three-dimensional cultures for cartilage-like tissue engineering.

The autologous chondrocyte transplantation technique has been introduced for the repair of articular cartilage defects. The advantage of transplanting chondrocytes cultured in suspension includes the in vitro expansion of cell numbers. However, the disadvantages include the potential leakage of cells from defects, dedifferentiation of cellular phenotype, and uneven distribution of cells. Transplantation of chondrocytes cultured in collagen gel resolves those problems. However, the expansion of cells in three-dimensional culture is more difficult than in monolayer culture, and for practical reasons only limited numbers of chondrocytes can be obtained from an unloaded area of the knee. To develop a method for the production of high-quality cultured grafts, we investigated the combination of monolayer culture for cell expansion and three-dimensional culture for maintenance of cell phenotype. Articular chondrocytes from rabbits were divided into four groups, exposed to various combinations of culture conditions, and cultured for a total of 3 weeks. Each group was evaluated histologically, biochemically, and biomechanically. Our findings showed that the combination of 2 weeks of monolayer culture followed by 1 week of three-dimensional culture resulted in the highest chondroitin sulfate levels, sufficient cell numbers, and adequate stiffness of the chondrocyte-collagen composites, giving optimal graft preparation.

Comparison of elastic versus rigid suture material for peripheral sutures in tendon repair.

BACKGROUND: For secure tendon repair, while core suture materials have been previously investigated, the optimum material for peripheral sutures remains unclear. METHODS: Transected bovine gastrocnemius tendons were repaired by 2-strand side-locking loop technique using no.2 braided polyblend polyethylene thread for the core suture. Then, 8-strand peripheral cross-stitches were added using either 2-0 rigid sutures (braided polyblend polyethylene) or USP 2-0-sized elastic sutures (nylon). The holding area of each peripheral suture was set at either 3 × 1 mm (shallow holding) or 6 × 2 mm (deep holding). Therefore, 4 groups were compared (the shallow-rigid, deep-rigid, shallow-elastic, and deep-elastic groups). The gap formation, ultimate tensile strength, and suture migration state were measured after 500 cyclic loadings (from 10 to 200 N). METHODS: The shallow-rigid group had inferior outcomes compared to the other groups. Although the deep-rigid group had the smallest gap and highest ultimate strength, all peripheral sutures had failure prior to core suture rupture. The two elastic groups showed no significant differences, irrespective of the size of the holding area. Suture migration did not occur in the two elastic groups until the ultimate strength was reached and the core suture ruptured. INTERPRETATION: Depending on the suturing method, rigid suture material may not be appropriate for peripheral sutures, when accompanying rigid core suture material. If peripheral sutures can be made with accurate deep holding, rigid suture material will provide favorable outcome. However, in other cases, elastic suture material is considered best for supporting a rigid core suture, as elasticity is another important factor for peripheral sutures.

Optimum suture material for locking technique in tendon repair: effects of suture friction in mobilization.

BACKGROUND: The 2-strand side-locking loop technique allows secure locking formation easily, yielding maximum tensile force. However, not all suture materials are suitable for this technique. METHODS: The bovine gastrocnemius tendons were transected and repaired end-to-end by the side-locking loop technique using USP2 braided polyblend, braided polyester, monofilament nylon, braided nylon, or monofilament absorbable polydioxanone sutures. A repetitive loading protocol from 10N to 100N was used, and the loading was repeated 10,000 times. In ruptured samples during the repetitive loading test, the number of loading was recorded. In samples which did not rupture, the ultimate tensile strength was measured after repetitive loading. After testing, ruptured sutures were examined microscopically. For comparison of ultimate tensile strength before and after repetitive loading, we performed a one-time loading test on samples which did not undergo the repetitive loading. FINDINGS: With monofilament nylon, braided nylon, or monofilament absorbable polydioxanone, suture rupture occurred during repetitive loading. In contrast, no suture rupture occurred with braided polyblend or braided polyester. Microscopic observation showed abrasion of the surface in braided polyester, though the friction effects were not seen with braided polyblend. The mean ultimate tensile strength before and after repetitive loading was 395N and 399N, respectively, for braided polyblend. For braided polyester, they were 208N and 174N, respectively. INTERPRETATION: Braided polyblend suture material has an excellent resistivity to friction and is suitable for the side-locking loop technique.

Optimally strong tendon repair using braided polyethylene strand: 2-strand heavy-gauge locking technique vs. multiple-strand technique.

BACKGROUND: We conducted an in vitro study to investigate the strongest tensile force for tendon repair using a braided polyblend suture strand material, employing a 2-strand heavy-gauge side-locking loop technique, comparing it with other multiple-strand repair techniques. METHODS: Using the United States Pharmacopeial Convention (USP) 2 and 5-sized braided polyblend strands, 3 repair techniques were evaluated after suturing transacted bovine gastrocnemius tendons: 2-strand side-locking loop, 4-strand Savage, and 6-strand Yoshizu-1 techniques. Ultimate tensile force and mode of failure at strand rupture were examined (n=5 for each combination). FINDINGS: The ultimate tensile forces was observed with USP2-side-locking loop (mean 402 N), USP5-side-locking loop (mean 748 N), USP2-Savage (mean 552 N), and USP2-Yoshizu-1 Groups (mean 598 N). The USP5-side-locking loop Group had proportionally greater ultimate tensile force than the USP2-side-locking loop Group. However, with the number of strands doubled or tripled, resulting strengths were only 1.4 times or 1.5 times greater. The mode of failure was rupture at the locking loop portion in all side-locking loop Group samples, pull-through of the strand from the tendon in all Savage Group samples, and either pull-through of the strand from the tendon (40%) or rupture at the knot (60%) in the Yoshizu-1 Group samples. INTERPRETATION: Greater numbers of strands do not achieve proportionally greater strong tensile force in the repaired tendon. When employing the side-locking loop technique for secured locking formation, the heavier strand yields markedly greater tensile force even with only 2 strands, and thus greater holding ability.

A new technique for small and secure knots using slippery polyethylene sutures.

BACKGROUND: Suture knots used in tendon surgery must be strong but small enough so that they do not hinder gliding. For this purpose, we devised a unique "antislip" knot. METHODS: Three suture materials were used: Ethibond, Fiberwire, and Nespron. They were tied with either the antislip knot using a pair of United States Pharmacopeia (USP) 2 sutures or with a conventional reef knot using USP2 single sutures. The volume and tensile strength of the knots were measured (n = 25 for each combination of suture and method). FINDINGS: The maximum tensile strength was observed with Fiberwire antislip knots with five throws (mean 587 N) and six throws (mean 590 N), and Nespron antislip knots with five throws (mean 554 N) and six throws (mean 552 N); no significant differences were found among the four knots. Tensile strength per volume showed maximum values with Fiberwire antislip knots with four throws (mean 17.4 N/microl) and five throws (mean 16.8 N/microl), and Nespron antislip knots with four throws (mean 17.6 N/microl) and five throws (mean 16.8N/microl), which were not significantly different and were over 1.25-fold greater than the value for a reef knot. Ethibond had less tensile strength than Fiberwire and Nespron. INTERPRETATION: The antislip knot is smaller for the same or greater strength than a conventional reef knot. The 4- or 5-throw antislip knot was most effective for slippery polyethylene sutures such as Fiberwire and Nespron. The antislip knot should improve biological healing of repaired tendons through accelerated rehabilitation.

Proximal half angle of the screw thread is a critical design variable affecting the pull-out strength of cancellous bone screws.

BACKGROUND: Screws with strong pull-out strength have been sought for the treatment of cancellous bone. We hypothesized that an obliquely angled screw thread has advantages over conventional vertical thread with a minimal proximal half angle. METHODS: Metal and bone screws were made of stainless steel and porcine cortical bone. Their proximal half angle was set at 0 degrees , 30 degrees , or 60 degrees . The screws were inserted into porcine cancellous bone. At 0 degrees , the thread faced the recipient bone vertically. Pullout tests at a rate of 30 mm/min (n=40, each screw type) and microcomputed tomography (n=6) were conducted. FINDINGS: The pull-out strength of the screws was maximal at 30 degrees ; 348.8 (SD, 44.1)N with metal and 326.6 (39.4)N with bone. It was intermediate at 0 degrees ; 301.9 (35.9)N with metal and 278.2 (30.6)N with bone. It was minimal at 60 degrees; 126.5 (39.0)N with metal and 174.8 (29.7)N with bone. Cancellous bone was damaged between the threads at 30 degrees , while intact cancellous bone was preserved between the threads at 0 degrees. INTERPRETATION: A proximal half angle of around 30 degrees is appropriate because the pullout force is applied to the recipient bone evenly. Commercial cancellous screws can be improved by changing the thread shape to minimize the damage to recipient bone.

Optimum surgical suture material and methods to obtain high tensile strength at knots: problems of conventional knots and the reinforcement effect of adhesive agent.

BACKGROUND: Strong suture material and a firmly tight knot that never loosens are necessary for tendon suture, but the appropriate combination of suture materials and the methods to make a knot are matters of uncertainty. METHODS: The tensile strength of four conventional tendon suture materials (Surgilon, Ethibond, Ethilon, PDS II) and newly developed FiberWire were examined. An experienced orthopedic surgeon formed surgical knots with USP2 wire (0.5-0.599 mm in diameter) by making loops and then pulled them at 20 mm/min using Instron. RESULTS: With the conventional surgical suture method (the addition of one throw on a surgeon's knot), Surgilon proved to have the highest tensile strength (163.6 +/- 6.5 N). Other suture materials, when tied under the same conditions, slipped and did not reach the ultimate tensile strength. When four additional throws were made, FiberWire provided the highest tensile strength (316.6 +/- 12.2 N) among the five suture materials tested (others were 140-200 N). When an adhesive agent, cyanoacrylate, was applied to a knot, PDS II provided the highest tensile strength (182.0 +/- 10.1 N). CONCLUSIONS: Our study suggests three suitable combinations of suture materials and methods for suture knot formation, depending on the site of surgery, that provide optimum treatment outcomes. Surgilon provides the most stable strength for general suture techniques. FiberWire is the strongest suture material for a site where a large number of throws is clinically possible. PDS II provides a strong suture when combined with cyanoacrylate reinforcement.