Repair of the central slip of extensor tendon and the open mallet using Mitek mini bone anchors

There has been a recent upsurge in the use of bone anchors in repairing hand tendon injuries, which substantiates our use of Mitek anchors in the late 1990s with good results. The objective of this study was to describe our technique of using Mitek bone anchors to repair open mallet and open central slip avulsion injuries, hence evaluating their post-operative outcomes. Four patients with open mallet injury and ten patients with open central slip avulsions were treated using the Mitek mini bone anchors. In each case, the extensor tendon was shaved off its point of insertion on the middle or distal phalanx. All patients were operated in within 2 days of the open injury without any conservative measures pre-operatively. Post-operatively, the joint was maintained in an extension with a single trans-articular Kirschner wire or splint for 2 weeks, followed by gradual mobilization and active and passive exercises. Each patient underwent an objective evaluation to assess joint stability, the joint’s range of motion and grip strength compared to the uninjured side. Patients also underwent a subjective evaluation at the end of the follow-up period. The operative procedure was successful in all but one patient. One patient needed a relook procedure. Two patients were lost to follow-up, while the rest were followed up for a mean duration of 11 months (range = 5–24 months). Subjectively, two patients had excellent results, seven had good results, two had fair, and one achieved poor results. The Mitek bone anchor is a useful tool to treat open extensor tendon injuries, especially ones where the tendon has been shaved off at its insertion on the bone.     

Reconstruction of the proximal interphalangeal joint collateral ligaments using the Mitek Micro Arc Anchor: an in vitro biomechanical assessment

Proximal interphalangeal joint (PIP) collateral ligament injuries are common and sometimes result in painful, stiff fingers. A number of techniques have been utilized in the past to reconstruct complete collateral ligament injuries. Recently, bone anchor systems have been described that allow collateral ligament reconstruction without the necessity of pull-out wires and other more cumbersome methods to reconstruct these ligaments. The Mitek bone anchor system has been used successfully in a variety of anatomic locations throughout the body to reattach soft tissues to bone. The current study was conducted to evaluate the biomechanical effects of the use of the Mitek Micro Arc Anchor in collateral ligament injuries of the PIP joint. In cadaveric PIP joints, the collateral ligament was isolated and then transsected in its mid substance. The authors compared suturing the ligament alone in standard fashion to repair of the ligament using a bone anchor inserted in the base of the middle phalanx. The joints were stressed to failure, with a lateral load applied at the distal end of the middle phalanx on a materials testing machine. The mean tensile failure loads of the two groups were the following: Mitek anchor, 16.4 +/- 3.7 N; suture repair, 19.3 +/- 7.6 N. The authors found no significant difference in the force required for failure of the repair or in the pattern of failure in the two groups. The Mitek Micro Arc Anchor appears to be adequate biomechanically to reconstruct the collateral ligaments of the finger PIP joint.     

微型骨锚重建指伸肌腱中央束止点的生物力学研究和临床应用

目的评价应用微型骨锚(mitek bone anchor)重建指伸肌腱中央束撕脱伤的疗效。方法将40指(10只手)新鲜冷冻手指分成对照组(丝线缝合)和骨锚组(骨锚),各组手指被固定到力学装置(Instron 1     

Surgical repair of central slip avulsion injuries with Mitek bone anchor--retrospective analysis of a case series.

The purpose of this study is to describe our technique of central slip repair using the Mitek bone anchor and to evaluate the treatment outcome. Eight digits in eight patients were reconstructed using the bone anchor: three little fingers, two middle fingers, two index fingers and one ring finger. There were two immediate and six delayed repairs (range from one day to eight months). Four patients had pre-operative intensive splinting and physiotherapy to restore passive extension of the proximal interphalangeal joint prior to central slip reconstruction. All patients have made good progress since surgery. No patient requires a second procedure and none of the bone anchors have dislodged or loosened. We conclude that the Mitek bone anchor is a reliable technique to achieve soft tissue to bone fixation in central slip avulsion injuries. We recommend that this technique be considered as a treatment option for patients requiring surgical repair.     

微型骨锚在锤状指治疗中的应用

指伸肌腱终腱止点处断裂和撕脱损伤是一种常见的手外伤,若处理不当可导致锤状指畸形.     

A technique for re-insertion following flexor tendon injuries in zone 1 using Mitek bone anchors

A technique for re-insertion of flexor digitorum profundus to the distal phalanx using Mitek bone anchors is described. In our series of seven procedures, there was no rupture of the repair. Internal fixation with Mitek bone anchors is reliable and has two main advantages of having no external component (e.g. button) and facilitating early mobilization.     

Repair of flexor digitorum profundus tendon avulsions from bone: an ex vivo biomechanical analysis

Avulsions or distal transections of the flexor digitorum profundus tendon are typically repaired by direct suture of the tendon stump to the distal phalanx. The optimal repair technique to withstand in vivo rehabilitation forces is unknown. Our objective was to determine the time-zero tensile mechanical properties of 4-strand tendon-bone repair site constructs performed with 3-0 and 4-0 sutures and with modified Kessler and modified Becker grasping techniques. We hypothesized that the 3-0 modified Becker grasping suture technique not described previously for the reattachment of tendon to bone would show improved biomechanical properties compared with the 4-0 or modified Kessler techniques. All modified Kessler repairs failed by suture pullout from the tendon, whereas all modified Becker repairs failed by rupture of the suture at the tendon-bone junction. Although the 3-0 modified Becker repair group showed greater ultimate force then the other groups (p <.01), tendon-bone gap observed did not differ markedly between Becker or Kessler groups. Neither suture caliber nor repair technique had a notable effect on strain at 20-N force, suggesting that early gap formation at the tendon-bone repair site may occur regardless of technique.     

Repair of chronic mallet finger deformity using Mitek micro arc bone anchor

Surgical correction of chronic mallet finger caused by terminal tendon disruption was carried out in 22 patients. The distal stump of the tendon was fixed to the base of the distal phalanx with a Mitek micro arc bone anchor. In all patients the mallet finger deformity was corrected. There were 15 patients with excellent results, 5 with good results, and 2 with fair results. None of the patients had a poor result. No further treatment was needed. The Mitek micro arc bone anchor system is a reliable alternative for the treatment of chronic mallet finger deformity without proximal interphalangeal hyperextension.     

应用微型骨锚重建指伸肌腱终腱止点--附6例报告

目的 探讨微型骨锚在指伸肌腱终腱止点撕脱伤修复中的临床疗效。方法 对6例指伸肌腱终腱止点撕脱患指，先用克氏针将远侧指间关节固定于过伸位，然后将Mitek mcro微型骨锚植人远节指骨基底背侧指伸肌腱附着处，再用锚尾部的4-0 Ethibond缝合线与撕脱的指伸肌腱缝合，重建止点。结果 6例全部获得随访，术后随访3～6个月，平均4．1个月。按Dargan功能评定方法评定：优4例，良2例。术后X线片未见骨锚松动、脱落。结论 微型骨锚用于修复与重建指伸肌腱终腱，操作简便，易掌握，疗效可靠。     

应用微型骨锚重建手指侧副韧带-附7例报告

目的探讨微型骨锚在修复手指侧副韧带撕脱伤中的临床疗效。方法2004年3月-2006年1月，对7例手指侧副韧带损伤的患者，先用一枚直径为0．8mm克氏针斜行将患指近侧指间关节固定于平伸位，然后采用1．3mm Mitekmero微型带双针40 Ethibond骨锚植入近节指骨头或中节指骨基底侧方侧副韧带的腱附着处，用锚尾部的缝合线缝合撕脱的侧副韧带重建起止点。结果术后7例获得3至11个月随访，平均4．8个月。按TAM功能评定方法评定：优6例，良1例。x线片示骨锚未见松动、脱落。结论微型骨锚用于修复与重建手指侧副韧带．其操作容易掌握，简便、快捷，疗效可靠。     

应用Sky bone expander system经皮椎体成型术的生物力学评价

目的应用Sky bone expander system在体外经皮椎体成型术治疗椎体压缩性骨折,观察并评价生物力学性能。方法选取8具尸体脊柱标本(T10～L2)并游离成40个椎体,测定骨密度后随机分为3组；Ⅰ组为空白对照组(n=20)；Ⅱ组为球囊经皮椎体成型术组即球囊组(n= 10)；Ⅲ组为应用Sky bone expander system经皮椎体成型术组即Sky组(n=10)。在C型臂X线机导引下对Ⅱ和Ⅲ组椎体经双侧椎弓根行充填PMMA。在万能材料试验机上将所有椎体前缘压缩至原来高度的50%,测得最大载荷及刚度；然后将Ⅰ组在随机分为ⅠA组和ⅠB组,分别用球囊和Sky bone expander system行椎体成型术,再次按前述加载方法将椎体前缘压缩至充填后高度得50%,测得高度、最大载荷及刚度变化。结果实验前各组骨密度(BMD)为(0．298～0．650)g/ cm~2,高度为(1．87～2．83)cm。实验后Ⅰ组椎体的最大载荷为(2 632．75±64．83)N,刚度为(602．70±30．24)N/mm；Ⅱ组椎体的最大载荷为(5 215．60±70．46)N,刚度为(1 012．32±92．45) N/mm；Ⅲ组椎体的最大载荷为(5 320．75±92．38)N,刚度为(980．40±73．63)N/mm；最大载荷方面：Ⅰ组与Ⅱ、Ⅲ、ⅠA和ⅠB组间差异有统计学意义(P＜0．05)。刚度方面：Ⅰ组与Ⅱ、Ⅲ、ⅠA和ⅠB组间差异有统计学意义(P＜0．05),Ⅱ、Ⅲ、ⅠA和ⅠB组间差异无统计学意义(P＞0．05)。结论Sky bone expander system可有效的恢复椎体的生物力学性能,可为临床提供一种新的经皮椎体成型术方法。     

Intersegmental spinal flexibility with lumbosacral instrumentation. An in vitro biomechanical investigation

Flexibility of the porcine lumbosacral spine was measured after application of six different types of surgical instrumentation, and in a control state. Fifteen adult pig spines were tested with flexion, extension, lateral bending, and axial rotation torques applied to the upper end with the pelvis fixed. Instrumentation was applied across two lumbar segments and the lumbosacral level (L5-6, L6-7, and L7-S1). Stereophotogrammetry was used to track markers applied to each vertebra. Intersegmental motion was measured as three angles and as the relative linear translation of adjacent transverse processes and spinous processes. Results showed that all instrumentation systems reduced intersegmental motion compared with the control state, except for minimal reduction at L5-6 by Harrington instrumentation in all loading directions, especially axial rotation. The pedicle screw systems were always the most rigid. After applying instrumentation, there were differences in the motion occurring at different anatomic levels, most commonly with the least motion occurring in the middle of the instrumented segment (L6-7). When intervertebral motion was expressed as the linear motion between adjacent spinous and transverse processes, the usual site of posterolateral fusion, it was 0.6 to 1.8 mm per degree of angular motion at the transverse processes and 1.3 to 2.1 mm per degree at spinous processes.     

An in vitro model to test the contribution of advanced glycation end products to bone biomechanical properties

We developed an in vitro model which provides the ability to test the effects of advanced glycation end products (AGEs), specifically pentosidine (PEN) and one of its inhibitors, the aminoguanidine (AMG), on cortical bone. This model allows modification of the extent of collagen cross-linking, while controlling other factors known to influence bone strength. In this in vitro model, young bovine cortical bone specimens were incubated in phosphate-buffered saline (PBS)+/-ribose (RIB, an inducer of AGEs formation)+/-AMG for 15 days at 37 degrees C. The mineral and organic matrix as well as biomechanical properties were examined. We found that (i) incubation+/-treatments did not induce collagen denaturation compared to specimens that were not incubated; (ii) neither treatment or incubation time effected the concentration of trivalent enzymatic cross-links pyridinoline and deoxypyridinoline. The non-enzymatic cross-link PEN was undetectable in specimens that were not incubated or that were incubated in PBS or AMG alone. However, PEN concentration increased significantly in specimens incubated with RIB, whereas ribose-induced PEN formation was markedly inhibited by AMG. (iii) Incubation+/-treatments did not change the mineral maturity, crystallinity or microhardness assessed by X-ray diffraction, X-ray microscopy analyses, FTIRM and micro-indentation tests. (iv) PEN concentration was not associated with biomechanical properties assessed by 3-point bending. In conclusion, this in vitro incubation model of young bovine cortical bone induced physiologic concentrations of PEN in the RIB+AMG group and is the first to show that AMG inhibits ribose-induced formation of PEN cross-links in bone while not affecting the organic and mineral phases. AGE concentration did not influence bending mechanical properties; however, the simple 3-point bending test we used was likely inadequate to demonstrate effects of AGEs on mechanical properties.     

Repair of cartilage lesions using biological implants. A comparative histological and biomechanical study in goats

We report the experimental use of three different biological implants to restore articular surface defects: glutaraldehyde-fixed bovine meniscal xenograft, glutaraldehyde-fixed bovine costal cartilage xenograft, and viable osteochondral allografts. The grafts were implanted in the knees of 19 goats who were allowed free-field activity and were studied for up to one year. The natural articular surfaces of meniscal fibrocartilage provided excellent articular surfaces at all times. Equally good articular surfaces were restored by host tissue growth covering costal cartilage grafts at six months, but by 12 months this surface had degenerated. The majority of the allografts survived and integrated with the host at six months, but many showed signs of failure at 12 months. Only three out of seven ungrafted defects healed completely at six months and the healed surfaces were degenerating at 12 months.     

微管结构仿生人工骨对犬腔隙性松质骨缺损的修复

目的建立一种新型松质骨缺损动物模型，同时评价应用纤维增强微管结构仿生人工骨修复该骨缺损的性能。方法成年犬双侧股骨下段分别制备2处直径10mm、深20min腔隙性松质骨缺损，以正交结构（A）组、同心结构（B）组仿生人工骨修复，设立磷酸钙骨水泥（calcium phosphate cement，CPC）（C）组、空白（D）组为对照，术后6、12、24周进行影像学、组织学、形态计量学观察骨缺损修复情况。结果未经治疗的骨缺损不能自行愈合；人工骨修复组6周新生骨开始长人，6、12、24周时A、B、C组的成骨面积比（％）分别为（4．09±0．96）、（6．78±1．27）、（3．10±0．83），（8．98±2．45）、（15．38±2．33）、（4．25±1．03），（19．86±4．57）、（38．25±6．79）、（4．97±0．90）；相应各组CPC残留面积比（％）为83．19±3．69、81．93±3．80、86．87±4．48，68．14±5．39、34．59±5．50、75．83±4．51，38．55±4．78、22．20±3．46、62．89±4．31；各组新生骨面积比（％）B〉A〉C（P〈0．01），CPC残留面积比（％）C〉A〉B（P〈0．01）。结论该骨缺损模型稳定、可靠；微管结构仿生人工骨在促进成骨、加快CPC降解速度上优于不具有微管结构的人工骨，同心结构具有最佳成骨和促CPC降解作用。     

中,下颈椎纵向撞击性损伤机制的实验研究

分析人体中、下颈椎承受纵向撞击力作用时的损伤机制、损伤阈值，为颈椎撞击性损伤的防护、诊治提供生物力学依据。应用成人男性新鲜尸体标本在CZZ-Ⅱ人体撞击试验机上行撞击实验。对C2～C4标本进行30J和50J能量的撞击，对C5～T1标本进行50和100J能量的撞击，由计算机数据采集系统得到撞击力峰值、冲量、撞击速度和撞击力作用时间等参数，以放射学诊断和解剖学观察为损伤判断依据。C2～C4在轴向撞击力作用下的损伤阈值为4112～4890N或30．2～34．2N·s，C5～T1在轴向撞击力作用下的损伤阈值为4824～6362N或33．6～43．0N·s。结果表明，轴向压缩载荷引起的颈椎损伤类型与其撞击能量的大小有关，较高撞击能量会产生颈椎的整体结构破坏，较低的撞击能量仅损伤颈椎的前、中柱结构。     

Experimental spiral fractures. An in vitro biomechanical comparison of lag-screw fixation to plate fixation

The rigidity and strength of fixation of experimental spiral fractures in canine tibias with triple lag-screw osteosynthesis were compared with fixation by six-hole dynamic compression plating (DCP). Lag-screw fixation was 71% to 77% as stiff in bending and 69% as stiff in torsion as plate fixation. When evaluated by torsion to failure, lag-screw specimens were 68% as strong as plate specimens. Although the difference in energy to failure in torsion was not statistically significant between the two methods, both fell considerably short of control values. The lag preparation was 9% as strong as intact controls, and the plate preparation was 21% as strong as intact controls. Long spiral fractures without comminution are amenable to triple lag-screw osteosynthesis with some loss of rigidity and strength when compared to single-plate fixation. This decrease in rigidity and strength may be outweighed by the avoidance of the stress protection phenomenon noted under rigid plates.