Risk of neurovascular injuries in flexor hallucis longus tendon transfers: an anatomic cadaver study

BACKGROUND: Flexor hallucis longus (FHL) tendon transfer is a frequently used treatment for both posterior tibial tendon insufficiency and chronic Achilles tendinopathy. We observed difficulties in harvesting the FHL tendon that may arise from cross-attachments with the flexor digitorum longus (FDL) tendon near the knot of Henry. The posterior tibial nerve is located nearby the decussation of these tendons. This study examined whether the difficult harvesting may be the cause of nerve injury. Methods: A cadaver study was performed on 24 foot specimens. In all feet, we used a double-incision technique. The FHL tendon was transected in the distal medial midfoot incision and retracted through the posteromedial hindfoot incision. After harvesting the FHL tendon, we exposed the posterior tibial nerve and its lateral and medial plantar branches to identify if any lesion had occurred. RESULTS: The retraction failed at the first attempt in all specimens because of the presence of cross-attachments between the FHL and FDL tendons. A more extensive dissection of the FHL and FDL tendons was therefore required. We found lesions in 33% of all foot specimens, including two complete ruptures of the medial plantar nerve. CONCLUSIONS: Harvesting of the FHL tendon when transection is made distal to the knot of Henry may cause injuries to the medial and lateral plantar nerves. Experience in this procedure may reduce the risk of nerve injuries but even then nerve lesions remain possible. The clinical significance of these nerve lesions is not described in literature and remains to be determined.     

Surgical Planning for Flexor Digitorum Longus Tendon Transfers: An Anatomic Study

Posterior tibial tendon dysfunction is often coupled with various degrees of hindfoot valgus and equinus. Preoperative planning is essential to appropriate procedure choice and surgical efficiency. The purpose of the present study was to assess the anatomy at the harvest site for flexor digitorum longus tendon transfer, specifically at the master knot of Henry. Thirty fresh-frozen below-the-knee cadavers were used for dissection. A standard anatomic approach was performed for posterior tibial tendon debridement and flexor digitorum longus tendon transfer. The flexor digitorum longus tendon was harvested and measured at the master knot of Henry. The present anatomic study evaluated the tendon width of the flexor digitorum longus tendon at a common harvest site. Of the 30 specimens, 20 (67%) measured 5 mm and 10 (33%) measured 4 mm. A 5.0-mm interference screw would be acceptable in each specimen and therefore would be the safest choice. A 4.0-mm interference screw would be acceptable in only 33% of the specimens. Males have a slightly more robust flexor digitorum longus tendon than females at the harvest site. This information will assist surgeons in preoperative planning during stage II flatfoot correction for posterior tibial tendon dysfunction.     

Biotenodesis screw for fixation of FDL transfer in the treatment of adult acquired flatfoot deformity

BACKGROUND: In stage II PTTD, flexor digitorum longus (FDL) tendon transfer with an adjunctive bony procedure is the most common method of surgical correction. This paper presents an alternative method of fixation with a biotenodesis interference screw (Arthrex Biotenodesis Screw System) that allows proper tensioning of the FDL tendon transfer. MATERIALS AND METHODS: We retrospectively reviewed 25 consecutive patients who underwent FDL tendon transfer utilizing a biotenodesis interference screw. Intraoperative stability was noted and any loss of correction was assessed postoperatively. RESULTS: Stable fixation was achieved in 24 of the 25 patients who underwent FDL tendon transfer for PTTD. We were not able to achieve stable fixation in one patient due to improper placement of the bone tunnel. This was recognized intraoperatively and did not affect the final outcome. CONCLUSION: This method is technically easier to perform than the recommended technique by the manufacturer. It can be performed through a slightly smaller incision without disrupting the normal interconnections between flexor hallucis long (FHL) and FDL tendon at the Knot of Henry.     

Comparison of transfer sites for flexor digitorum longus in a cadaveric adult acquired flatfoot model

Posterior tibialis tendon (PTT) dysfunction (PTTD) is associated with adult acquired flatfoot deformity. PTTD is commonly treated with a flexor digitorum longus (FDL) tendon transfer (FDLTT) to the navicular (NAV), medial cuneiform (CUN), or distal residuum of the degraded PTT (rPTT). We assessed the kinetic and kinematic outcomes of these three attachment sites using cadaveric gait simulation. Three transfer locations (NAV, CUN, rPTT) were tested on seven prepared flatfoot models using a robotic gait simulator (RGS). The FDLTT procedures were simulated by pulling on the PTT with biomechanically realistic FDL forces (rPTT) or by pulling on the transected FDL tendon after fixation to the navicular or medial cuneiform (NAV and CUN, respectively). Plantar pressure and foot bone motion were quantified. Peak plantar pressure significantly decreased from the flatfoot condition at the first metatarsal (NAV) and hallux (CUN). No difference was found in the medial–lateral center of pressure. Kinematic findings showed minimal differences between flatfoot and FDLTT specimens. The three locations demonstrated only minimal differences from the flatfoot condition, with the NAV and CUN procedures resulting in decreased medial pressures. Functionally, all three surgical procedures performed similarly. Published 2013 by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 32:102–109, 2014.     

Influence of tendon transfer site on moment arms of the flexor digitorum longus muscle

BACKGROUND: Adult acquired flatfoot is a common condition that leads to significant morbidity. Along with bony procedures to operatively treat this condition, transfer of the flexor digitorum longus (FDL) tendon to the medial cuneiform or navicular is routinely performed. The goal of this tendon transfer is to increase the capacity of the FDL to invert the hindfoot and control the transverse tarsal joints. However, it is not known whether this biomechanical goal is met or whether one transfer site produces a larger mechanical advantage compared to another site. The purpose of this study was to calculate FDL muscle moment arms at the hindfoot with two clinically relevant transfer locations to quantify the change in mechanical advantage of the FDL after tendon transfer. METHODS: In seven cadaver specimens, muscle moment arms of the FDL with respect to hindfoot motion were measured using the tendon excursion method before and after the FDL was transferred to the plantar aspect of the navicular and medial cuneiform. The position and orientation of the foot and excursion of the FDL tendon were measured with an optoelectronic measurement system. RESULTS: The FDL moment arm did not increase after tendon transfer to either the medial cuneiform or navicular when compared to its native site. There were significant decreases in FDL moment arm when transferred from its native site to the medial cuneiform (56% decrease, p=0.018) and navicular (46% decrease, p=0.026). CONCLUSIONS: In contrast to the clinical proposition that FDL transfer to the navicular or medial cuneiform increases this muscle's mechanical advantage to invert the hindfoot, this cadaver study suggests that, to the contrary, FDL muscle moment arms decrease after tendon transfer.     

拇长屈肌腱断裂修复方法选择的探讨

[目的]介绍拇长屈肌腱断裂的治疗方法。[方法]共治疗拇长屈肌腱断裂15例，拇长屈肌腱断裂残端小于0．5cm，则给予切除，末节指骨钻孔钢丝缝合固定；肌腱断裂部位距掌指关节1cm以内，应用肌腱劈开延长，吻合口避开拇长屈肌腱鞘狭窄区；其余行直接吻接。[结果]所有病例均获得满意疗效，无术肌腱粘连和断离的发生。[结论]本方法修复肌腱获得了较好的效果，值得选用。     

胫骨骨折髓内钉固定术后屈趾畸形(附5例临床分析)

目的探讨胫骨骨折髓内钉固定术后屈趾畸形的发生机制及防治措施。方法362例胫骨骨折患者施行髓内钉固定手术,其中5例(1.4%)术后出现屈趾畸形,其临床表现为跛行、踝关节中立位足趾屈曲畸形,背伸时畸形加重,跖屈位畸形减轻。保守治疗无效,均行拇长屈肌及趾长屈肌肌腱"Z"形延长术。结果5例术后平均随访19.7(16~24)月。术后患者中立位足趾屈曲畸形消失,步态均恢复正常,踝关节背伸时足趾轻度屈曲畸形。拇长屈肌及趾长屈肌肌力5级。结论胫骨骨折髓内钉固定术后足趾屈曲畸形为少见并发症,其发生可能与术前拇长屈肌及趾长屈肌的损伤未得到有效治疗,术中髓内钉导针、扩髓器对拇长屈肌、趾长屈肌的损伤或术后小腿深后骨筋膜鞘内压力增高引起的肌肉缺血、纤维化改变有关;肌腱延长术是有效的治疗方法。     

Interference Screw Fixation and Short Harvest Using Flexor Digitorum Longus (FDL) Transfer for Posterior Tibial Tendon Dysfunction: A Technique

Posterior tibial tendon dysfunction is a common clinical entity treated by foot and ankle specialists, and numerous surgical treatments are available to the modern foot and ankle surgeon. Fixation methods are constantly evolving as new products are developed and new uses for existing products are attempted. Interference screw fixation is the gold standard fixation for tendon autograft and allograft in orthopedic sports medicine. The technique that we describe in this article uses a less extensive harvest of the flexor digitorum longus tendon and a sound fixation method using an interference screw positioned in the tarsal navicular.     

Biomechanical evaluation of open suture anchor fixation versus interference screw for biceps tenodesis

Biceps tenodesis provides reliable pain relief for patients with biceps tendon abnormality. Previous cadaver studies have shown that, for biceps tenodesis, an interference screw provides biomechanical strength to failure superior to that of suture anchors. This finding has led some providers to conclude that screw fixation for biceps tenodesis is superior to suture anchor fixation. The purpose of the current study was to test the hypothesis that the strength of a 2-suture-anchor technique with closing of the transverse ligament is equal to that of interference screw fixation for biceps tenodesis.In 6 paired, fresh-frozen cadaveric shoulder specimens, we excised the soft tissue except for the biceps tendon and the transverse ligament. We used 2 different methods for biceps tenodesis: (1) suture anchor repair with closing of the transverse ligament over the repair, and (2) interference screw fixation of the biceps tendon in the bicipital groove. Each specimen was preloaded with 5 N and then stretched to failure at 5 mm/sec on a materials testing machine. The load-to-failure forces of each method of fixation were recorded and compared. Mean loads to failure for the suture anchor and interference screw repairs were 263.2 N (95% confidence interval [CI], 221.7-304.6) and 159.4 N (95% CI, 118.4-200.5), respectively. Biceps tenodesis using suture anchors and closure of the transverse ligament provided superior load to failure than did interference screw fixation. This study shows that mini-open techniques using 2 anchors is a biomechanically comparable method to interference fixation for biceps tendon tenodesis.     

Minimally invasive method of harvesting the flexor digitorum longus tendon: a cadaver study

BACKGROUND: The flexor digitorum longus (FDL) tendon is harvested for use in the reconstruction of dysfunctional adjacent tendons such as the posterior tibial and the Achilles tendons. The approach to harvest the FDL tendon in the midfoot region is through an incision along the medial border of the foot. This approach involves dissection quite deep in the foot across neurovascular structures in the vicinity placing them at risk. The purpose of this cadaver study was to test the feasibility and safety of a minimally invasive technique, and also to define the relevant topographical surface and deeper surgical anatomy. METHODS: In 83 cadaver feet, the FDL tendon was harvested proximally in the hindfoot after it was cut through a small plantar incision in the midfoot. All the tissues superficial to the FDL tendon were then reflected to check for damage to the adjacent neurovascular structures. Measurements were obtained to define the location of the point of division of the FDL tendon in relation to the plantar surface of the foot and the adjacent neurovascular structures. RESULTS: In all of the 83 feet it was possible to harvest the FDL using this technique. In 11 feet (13.25%), a connecting band to the flexor hallucis longus tendon (FHL) required division. No damage was apparent to the adjacent neurovascular structures. The FDL division was located topographically on the plantar surface of the foot, approximately midway between the back of the heel and the base of the second toe and at this midpoint, about two-thirds of the width medially from the lateral border of the foot. CONCLUSIONS: The FDL tendon can be harvested in the hindfoot after its division through a small plantar incision in the midfoot. Surface anatomy guides placement of the plantar incision over the FDL division. CLINICAL RELEVANCE: The plantar approach when compared to the medial approach for harvesting the FDL tendon in the midfoot may be associated with a smaller incision, minimal dissection, lesser risk to adjacent neurovascular structures and lesser morbidity.     

腓骨骨折术后并发(足母)趾屈曲畸形的治疗

目的 探讨腓骨骨折切开复位内固定术后并发拇趾屈曲畸形的病因、临床表现、解剖学特征、诊断及治疗方法。方法 1996年10月至2004年3月，腓骨骨折术后并发拇趾屈曲畸形患者33例，男19例，女14例；年龄22-49岁，平均33．2岁。其中合并踝关节骨折24例，根据Lauge—Hansen分型：旋前-外旋型18例，旋后-外旋型4例，旋前-外翻型2例；胫腓骨远端1／3螺旋形骨折9例。腓骨骨折均行切开复位钢板螺钉内固定术。患者均于术后1-5个月，平均3个月出现拇趾屈曲畸形。其中单纯拇趾屈曲畸形19例，伴二、三趾屈曲畸形8例，伴二至五趾屈曲畸形6例。采用单纯肌腱粘连松解术、单纯拇长屈肌腱延长或合并趾长屈肌腱延长术矫正畸形。结果19例单纯拇趾屈曲畸形患者，7例行单纯拇长屈肌腱粘连松解术，12例行拇长屈肌腱延长术。14例合并其余足趾屈曲畸形患者，6例行单纯拇长屈肌腱延长术，8例行拇长屈肌腱合并趾长屈肌腱延长术。术后随访2-10个月，平均6个月，所有患者足趾畸形完全矫正，疼痛缓解，步态及穿鞋改善，无畸形复发。结论 腓骨骨折术后并发拇趾屈曲畸形，拇长屈肌腱与骨折处粘连是重要因素。在Henry结部位，拇长屈肌腱与趾长屈肌腱之间存在腱性连接的解剖变异，对于足部矫形手术具有特殊的临床意义。     

Do the dimensions of the distal phalanges allow suture anchor fixation of the flexor digitorum profundus? A cadaver study

This study was done to identify whether the dimensions of the distal phalanges allow suture anchor fixation of the flexor digitorum profundus tendon. Forty pairs of hands were dissected to measure the anteroposterior and lateral dimensions of distal phalanges of all digits. The mean anteroposterior depth of the distal phalanx at the insertion of the tendon was found to be 4.7?mm for the little finger, 5.4?mm for the ring finger, 5.9?mm for the middle finger, 5.4?mm for the index finger and 6.9?mm for the thumb respectively. The commonly available anchors and drill bits for fingers were found to be suboptimal for anchoring the flexor digitorum profundus tendon to the distal phalanx of the little finger. The drill bits used for these anchors were found to be too long for the little fingers and some ring and index fingers.     

Disintegration of an absorbable rotator cuff anchor six weeks after implantation

Rotator cuff failure by suture-bone or suture anchor pull-out, suture breakage, knot slippage, and tendon pull-out are well described. I report a case of early disintegration of a bioabsorbable suture anchor. A 77-year-old woman underwent arthroscopic rotator cuff repair. On suspecting failure, the repair was repeated 40 days later. Arthroscopy revealed disintegration of the suture loop from the anchor. Open rotator cuff repair was then performed with transosseous suture and metallic anchors.     

Biodegradable Shoulder Anchors Have Unique Modes of Failure

Biodegradable suture anchors have facilitated and revolutionized arthroscopic tissue-to-bone repair, especially in the shoulder. However, the anchor is but a part of the repair construct, which also includes a suture, tied in a knot, that attaches the tissue (tendon or labrum) to bone. Bioabsorbable anchors may result in loose bodies. Two cases are reported as sentinel events highlighting this potential risk. In the first case, combining a nonabsorbable suture (forming the anchor eyelet) with an anchor body made from rapidly degrading copolymer resulted in the suture becoming a loose body as the anchor body reabsorbed. In the second case, a portion of the eyelet and upper screw thread, itself composed of a biodegradable copolymer, became a loose body as the anchor absorbed, perhaps because the eyelet became proud with regard to the host bone during cyclic loading. Biodegradable anchors offer many advantages over metal anchors but do not eliminate the risk of a glenohumeral loose body. Unexpected postoperative symptoms such as painful catching, popping, or “squeaking” may indicate a glenohumeral loose body and warrant an arthroscopic evaluation. In the future, improved shoulder suture anchor design may lower the risk of this complication.     

Anatomy of Master Knot of Henry: A morphometric study on cadavers

Objective

The objective of this study was to evaluate the features of flexor hallucis longus (FHL), flexor digitorum longus (FDL) and flexor digitorum accessorius (FDA) muscles with relevance to the tendon grafts and to reveal the location of Master Knot of Henry (MKH).

Comparison of pullout button versus suture anchor for zone I flexor tendon repair

PURPOSE: To evaluate the clinical outcome after repair of zone I flexor tendon injuries using either the pullout button technique or suture anchors placed in the distal phalanx. METHODS: Between 1998 and 2002 we treated 26 consecutive zone I flexor tendon injuries. Thirteen patients had repairs from 1998 to 2000 using a modified pullout button technique (group A) and 13 patients had repair using suture anchors placed in the distal phalanx (group B). Patient characteristics were similar for both groups. The same postoperative flexor tendon rehabilitation protocol and follow-up schedule were used for both groups. Evaluation included range of motion, sensibility and grip strength, failure, complications, and return to work. The Student t test was used to determine significant differences. RESULTS: All patients completed 1 year of follow-up evaluation. There were 2 infections in group A that resolved with oral antibiotics and no infections in group B. There were no tendon repair failures and no repeat surgeries in either group. At final follow-up evaluation there were no statistically significant differences for the following end points: sensibility (Semmes-Weinstein monofilament testing and 2-point discrimination), active range of motion (at the proximal interphalangeal joint, distal interphalangeal joint, or their combined motion), flexion contracture (at the proximal interphalangeal joint, distal interphalangeal joint, or their combined contracture), and grip strength (injured tendon as a percent of the contralateral uninjured tendon). The suture anchor group had a statistically significant improvement for time to return to work. CONCLUSIONS: There was no significant difference in the clinical outcome after flexor tendon repair using either suture anchors or the pullout button technique. A significant improvement was found for time to return to work for repairs using the suture anchor technique. Flexor tendon repair can be achieved using suture anchors placed in the distal phalanx, thereby avoiding the potential morbidity associated with the pullout button technique. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level III.     

缝线锚钉修复腱性组织止点区断裂伤的失效原因分析

目的 通过对缝线锚钉修复腱性组织止点区断裂伤的失效原因进行分析,旨在提高此类内固定修复腱性组织止点区断裂的疗效,减少锚钉失效的发生率.方法 2006年6月至2008年6月,对收治的7例应用缝线锚钉治疗腱性组织止点区断裂失效患者进行回顾性研究,其中男5例,女2例;年龄22～64岁,平均41岁.跟腱断裂2例,肩袖撕裂1例,喙锁韧带断裂1例,髌韧带撕脱1例,膝内侧副韧带断裂1例,胫前肌腱止点处断裂1例.7例患者于伤后5 h～4个月行切开腱性组织修复术,锚钉类型为强生GⅡ快速增强缝线锚钉(形状类似倒钩)和强生FastinRC带螺纹锚钉.术后随访10d～3周发现锚钉失效.结果 7例失效患者全部为锚钉脱出,无缝线断裂及锚钉毁损,且原始损伤均为较粗大腱性组织断裂.锚钉失效原因:手术操作不当4例,锚钉选择失误2例,患者依从性差而过早活动1例.患者因患处疼痛均于术后2个月左右行锚钉取出术.结论 应用锚钉前需要对锚钉装置有详细的了解,骨质、锚钉类型、锚钉置入方向及手术技巧的掌握等都影响锚钉固定的疗效.     

A biomechanical comparison of EndoButton versus suture anchor repair of distal biceps tendon injuries

The purpose of this study was to compare suture anchor and EndoButton repair of distal biceps injuries in a human bone-tendon model. Right and left arm repairs were alternately performed with either the EndoButton or 2 single-loaded 5-mm suture anchors. Each construct was cyclically loaded by use of a servohydraulic materials testing machine. Initial and final displacements were recorded. All repairs were then loaded to ultimate failure. Ten millimeters of displacement was designated the clinical failure point. The EndoButton group had more stiffness than the suture anchor group during initial cyclic loading (P = .01). There were no differences in final displacement measured after cyclic loading (2.06 mm for suture anchors and 2.58 mm for EndoButton). The EndoButton group had a 16% greater ultimate tensile load than the suture anchor group (274.77 N vs 230.06 N). The EndoButton group also had a 16% higher load to clinical failure (249.95 N vs 209.56 N). These differences were not statistically significant. The EndoButton and suture anchors provide comparable fixation strength for the repair and rehabilitation of distal biceps tendon ruptures.     

Distal anatomical relationship of the flexor hallucis longus and flexor digitorum longus tendons

BACKGROUND: The distal attachment of the flexor hallucis longus (FHL) tendon with the flexor digitorum longus (FDL) tendon varies antomically. The presence of a strong link between the two tendons can preserve distal function if one of the tendons is used for transfer. METHODS: Twenty-four cadaver legs were dissected, and the distal relationship of the FHL tendon with the FDL tendon was analyzed. The width of the tendons and their attachments were measured to the closest 0.5 mm. RESULTS: Three different configurations were found. In type 1, a tendinous slip branched from the FHL to the FDL (10 of 24 feet). In type 2, a slip branched from the FHL to the FDL and another from the FDL to FHL (10 of 24). In type 3, no attachment was present (four of 24). In four cadavers the attachment was different in the right and left feet. CONCLUSION AND CLINICAL RELEVANCE: The absence of a cross connection between the two tendons in the foot may be more frequent than previously reported. Three configurations of the anatomical relationship of the distal FDL to FHL tendons were found in this study with a small sample size. Based on these findings, to preserve the distal function of the FDL after transfer of the proximal FDL tendon, routine tenodesis should be done or a wider exposure and tenodesis in type 3 variations.