Anatomy of the anterior interosseous innervation of the pronator quadratus: evaluation of structures at risk in the single dorsal incision wrist denervation technique

PURPOSE: Patients with chronic wrist pain often are treated with wrist denervation, which typically involves transecting both the anterior interosseous nerve (AIN) and the posterior interosseous nerve. A single dorsal incision approach is an improvement over the more traditional multiple-incision technique. The purpose of our study was to describe the branches of the AIN to the pronator quadratus and evaluate the risk of denervation with the single dorsal incision technique. METHODS: Twelve fresh-frozen cadaver forearms were dissected. The branches of the AIN to the pronator quadratus were identified and the individual branch points were measured from the articular edge of the distal radius. Wrist denervation was then performed on each specimen through the single dorsal incision (as suggested by Berger). RESULTS: There were an average of 3 branches from the AIN to the pronator quadratus. All forearms had at least 1 branch to the pronator quadratus more proximal to the distal end of the dorsal skin incision; however, in only 2 of the forearms was the most proximal branch more than 2 cm proximal to the distal end of the dorsal skin incision. CONCLUSIONS: Wrist denervation through the recommended single dorsal incision poses a serious risk for completely denervating the pronator quadratus. Therefore the resection of the AIN must be performed close to the distal margin of the pronator quadratus.     

Möglichkeiten und Ergebnisse der Lappenlastiken aus dem Arteria-interossea-System zur Defektdeckung im Handbereich

Introduction

Intensive anatomical studies of the anterior ulnar artery system have given rise to many new options for reconstruction of soft tissue or bone defects of the hand using local proximal and distal pedicle flap transfer.

Patients and Method

In 21 patients, consisting of 19 males and 2 females aged between 11 and 71 years, a flap transfer from the interosseus artery system has been performed. In a retrospective clinical study the following criteria were examined: type and size of flap, complications and subjective judgement of the donor site by the patient (very good, good, acceptable or fair).

Results

A total of 15 fascio-cutaneous posterior interosseous flaps, 1 anterior interosseus flap and 5 proximally based pronator quadratus flaps (3 muscle and 2 muscle-bone flaps) were carried out. The mean flap size was 12x6 cm for the posterior interosseus flaps and 7x4 cm for the anterior interosseus flaps. The entire pronator quadratus muscle was used for proximally based muscle flaps. The size of each of the distally based myo-osseus pronator quadratus flaps was 1x 2 cm. In 14 patients primary healing was achieved. The donor site was judged by 13 patients to be good, by 6 as acceptable and by 2 as fair.

Discussion

The posterior interosseus flap transfer is the preferred method of choice for defect reconstruction in the region of the distal third of the forearm, the first commissure of the hand and the metacarpal region because of its constant anatomy and minor functional donor site defects. The anterior interosseus flap technique has proven to be of minor value because of the large functional and aesthetic donor site defects compared to other treatment options. The proximally based pronator quadratus muscle flap is an elegant variation for defects of the distal forearm down to the rasceta. The distally based myo-osseus variation is one of the possible vascularized bone grafts in exceptional circumstances for reconstruction of therapy-resistant atrophic fractures at the carpal level. Because of the small vessel size distally based interosseous flaps seem to be contraindicated in patients with pre-existing trauma of the distal forearm and wrist level.     

An anatomical study of the anterior interosseous nerve and its innervation of the pronator quadratus muscle

This anatomical study of 40 upper limbs from cadavers investigated the branching pattern of the anterior interosseous nerve in its distal part using the operating microscope. An articular branch to the wrist joint and/or the distal radioulnar joint was only found in seven of the 40 specimens and was always a small terminal continuation of the anterior interosseous nerve after the nerve had passed through the pronator quadratus and innervated it. Therefore, we do not recommend division of the anterior interosseous nerve from the dorsal approach through the interosseous membrane before it gives off its muscular branches to the pronator quadratus. This risks damage of the innervation of this muscle of importance for initiation of hand pronation.     

Intraosseous Vascularity of the Distal Radius: Anatomy and Clinical Implications in Distal Radius Fractures

This study aimed to describe the intraosseous blood supply of the distal radius and its clinical implications in distal radius fractures. Twelve adult wrists from fresh cadavers (six males, six females, 50–90 years of age, mean 68 years) were injected through the brachial artery with latex. Dissections were performed using magnifying loupes and hands were processed using the Spalteholz technique. The distal radius was supplied by three main vascular systems: epiphyseal, metaphyseal, and diaphyseal. The palmar epiphyseal vessels branched from the radial artery, palmar carpal arch, and anterior branch of the anterior interosseous artery. These vessels entered the bone through the radial styloid process at level of the Lister's tubercle but palmar and sigmoid notch. The dorsal contribution to Lister's tubercle is to the dorsal epiphyseal vessels. The intraosseous point of entry to the dorsal epiphyseal vessels was from the fourth and fifth extensor compartment arteries. In the metaphyseal area, we found numerous periosteal and cortical branches originating deep in the pronator quadratus and the anterior interosseous artery. These branches provided the main supply to the distal radius. Vessels perforated the bone and formed an anastomotic network. In the diaphyseal area, only the nutrient vessel provided intraosseous vascularity in the distal radius. Numerous metaphyseal–epiphyseal branches arise within the pronator quadratus and the anterior interosseous artery and course towards the distal radius. These branches may be fundamental to the healing of the distal radius fractures and make nonunion a rare complication.     

Anatomy and intracompartmental pressure measurement technique of the pronator quadratus compartment

The compartment of the pronator quadratus muscle in 25 cadaver specimens is described. Defined by the radius, ulna, and distal interosseous membrane dorsally and the pronator quadratus fascia on the palmar side, the osteofibrous walls of the compartment confine the pronator quadratus muscle within a noncompliant space. A safe and reliable location for compartment pressure measurement was defined at a site 4 cm proximal to the scaphoid tubercule, on the radial side of the flexor carpi radialis tendon and on the ulnar side of the radial artery. These clear anatomic definitions might be useful in diagnosis of compartment syndrome of the pronator quadratus; a clinical investigation may be justified on the basis of pressure measurements made using this technique.     

The blood supply of the human distal radioulnar joint and the microvasculature of its articular disk.

The arterial blood supply of the distal radioulnar joint was investigated in 35 upper extremities taken from 22 fresh cadavers (11 newborns and 11 adults using the India ink injection and tissue-clearing techniques according to Spalteholz). Microvasculature of the articular disk of the distal radioulnar joint was also performed in 35 articular disks taken from 22 fresh human cadavers, 11 newborn and 11 adults using the same technique. It was found that the general blood supply to the joint is received mainly from the palmar and dorsal branches of the anterior interosseous artery. These branches, after dividing at the proximal border of the pronator quadratus, arborize in a fanlike fashion around the joint and their small ramifications penetrate and vascularize the capsule and the articular disk from the palmar, dorsal, and medial sides. The terminal branches of the anterior interosseous artery reinforced by the posterior interosseous artery and a small branch of the ulnar artery give the direct peridiscal vessels to the palmar, medial, and dorsal margins of the articular disk, which arborize and anastomose with one another and form the terminal capillary networks that end at the peripheral segments of the disk in a series of terminal capillary loops, leaving the inner segments devoid of blood vessels. The posterior interosseous artery anastomoses at the distal part of the forearm with one of the terminal rami of the dorsal branch of the anterior interosseous artery and, in that way, contribute to the vascularization of the dorsal capsule of the distal radioulnar joint. The ulnar artery gives off a small branch that anastomoses with one of the terminal ramifications of the palmar branch of the anterior interosseous artery and contributes to the formation of a small arterial arch on the anteromedial side of the distal ulna, supplying the anteromedial capsule and the basistyloid area of the ulna. Both ulnar and radial arteries contribute to the vascularity of the joint through the collateral network of the palmar and dorsal carpal arches. In the articular disk, the major central portion of the disk is avascular and only its peripheral, palmar, medial, and dorsal margins are vascularized. The proportion of vascularized zone to avascular zone depends on the age of the subject and, in newborns, is approximately 33%. In adults, only 25% of the peripheral segments are vascularized.(ABSTRACT TRUNCATED AT 400 WORDS)     

前臂背侧嵌合骨皮瓣的应用解剖学研究

目的为前臂背侧嵌合骨皮瓣的设计提供解剖学基础。方法在22例成人上肢标本上解剖,观测骨间后动脉皮支分布,支配尺侧腕伸肌神经支与血管交叉点血管的外径及骨间后动脉与前动脉吻合情况。同时观测尺骨茎突近端5cm范围内,尺骨背侧骨膜血管支数目及血运来源。结果骨间后动脉沿途发出6-10个皮支,在深筋膜浅层形成丰富血管网吻合。可分为两种类型,Ⅰ型：间隔1-2cm发出皮支（15例）;Ⅱ型：分远、近两组（7例）。支配尺侧腕伸肌神经支与血管交叉点动脉外径（1．4±0．2）mm。在尺骨茎突近侧（2．4±0．5）cm处骨间后动脉与前动脉腕背支形成恒定吻合。尺骨茎突近侧5cm范围内,骨间后动脉向尺骨远段发出（3．0±0．8）支骨膜支（19例）;骨间后动脉发出2支骨膜支,骨间前动脉背侧支发出1支骨膜支（2例）;骨间前动脉背侧支发出2支骨膜支（1例）。结论以骨间后动脉为蒂可切取前臂背侧皮瓣、尺骨远端骨瓣形成嵌合组织瓣,修复手部皮肤缺损合并小块骨组织缺损。     

以骨间前动脉及背侧支为蒂组织瓣的临床应用

目的报道以骨间前动脉及背侧支为蒂组织瓣移位术的手术方法。方法临床设计以骨间前动脉及背侧支为蒂的组织瓣共20例；其中逆行岛状皮瓣4例，逆行岛状骨瓣4例，顺行岛状骨瓣2例，逆行岛状骨膜瓣2例，逆行岛状骨皮瓣8例。应用组织瓣修复手背、虎口皮肤缺损，修复掌骨缺损、尺骨骨不连、月骨无菌性坏死等。结果11例皮瓣和骨皮瓣全部成活，1例皮瓣远端部分坏死，经植皮后愈合。术后随访3个月～4年，受区移植骨全部骨性愈合，手部功能满意。结论以骨间前动脉及背侧支为蒂的组织瓣可设计成多种类型，是修复手及前臂复合组织缺损的良好供区。     

The anatomic basis of the fourth dorsal metacarpal flap: a cadaveric dissection

PURPOSE: To study the vascularization of the fourth dorsal intermetacarpal space and to determine the contribution of the dorsal metacarpal artery and the interosseous muscle fascia to flap viability. The fourth dorsal intermetacarpal space is considered to be less reliable as a donor site because of previously reported vascular variations. METHODS: We performed 15 cadaver dissections. The vascular tree was injected with black latex through the radial and ulnar arteries at the forearm. The skin paddle was designed within the fourth intermetacarpal space. The proximal border was placed at the wrist joint line. The distal border was located 1 cm proximal to the head of the fourth and fifth metacarpal. The width of the skin paddle was based on whether the donor site could be closed directly. A zigzag incision was performed from the distal end of the skin paddle to the volar edge of the interdigital web. The borders of the skin paddle were outlined down to the fascia of the dorsal interosseous muscle. Once the fourth dorsal metacarpal artery was identified each vascular connection was dissected and recorded. RESULTS: The fourth dorsal metacarpal artery was identified in all specimens under the dorsal interosseous muscle fascia. The distal recurrent branch consistently entered the base of the flap superficial to the extensor digitorum communis tendon of the small finger and the dorsal interosseous muscle fascia. Cutaneous perforators branching off the dorsal metacarpal artery were not found consistently. CONCLUSIONS: Reliable flaps can be raised from the fourth dorsal intermetacarpal space based solely on the distal recurrent branch, excluding the dorsal metacarpal artery and interosseous muscle fascia.     

骨间前神经旋前方肌支移位在高位尺神经损伤中的应用

目的研究高位尺神经损伤后用骨间前神经旋前方肌肌支移位修复尺神经深支的手术方法。方法2002年10月-2005年8月，对18例高位尺神经损伤的患者，应用骨间前神经旋前方肌肌支移位与尺神经腕部深支进行吻合。结果术后15例获得随访，随访时间为3个月～3年，平均1．7年。手内肌肌力恢复M2 2例，M3 2例，M4 6例，M5 5例，优良率为73％。结论骨间前神经旋前方肌支转位修复尺神经深支可达到肌支-肌支修复，缩短了神经再生的距离和时间，有利于手内在肌功能的恢复，是一种有效的手术方法。     

以骨间前动脉背侧支为蒂桡骨皮瓣的临床应用

目的为临床提供一种新的骨皮瓣移位术式。方法１０侧成人上肢标本经肱动脉灌注乳胶后，对其骨间前动脉背侧支的起始部位、口径、长度及其皮支、骨膜支的分布进行显微解剖观察。临床设计以骨间前动脉背侧支为蒂的桡骨皮瓣逆行移位，骨皮瓣中桡骨瓣支撑于第一、二掌骨间或修复掌骨缺损，皮瓣修复虎口、手背尺桡侧的皮肤缺损。结果临床应用６例，皮瓣全部成活。术后随访４～１２个月，受区移植骨已骨性愈合。结论骨间前动脉背侧支为蒂的逆行桡骨皮瓣，适用于修复掌部软组织合并掌骨缺损及重度虎口挛缩的病例。     

An anomaly of the median artery associated with the anterior interosseous nerve syndrome.

The anterior interosseous nerve syndrome is characterized by paralysis of the flexor pollicis longus muscle, the flexor digitorum profundus muscle to the index and middle fingers, and the pronator quadratus muscle. The most common cause is entrapment of the anterior interosseous nerve near its origin from the median nerve by a variety of structures. Compression is most frequently caused by the deep head of the pronator teres muscle, or the fibrous arcade of the flexor digitorum superficialis muscle. Vascular compression has been reported infrequently. A patient with anterior interosseous nerve syndrome was found at operation to have the median artery passing through the anterior interosseous nerve just below the elbow. This artery has not previously been associated with the syndrome. A cadaver dissection confirmed the relationship.     

Anatomical features of the pronator quadratus muscle related to minimally invasive plate osteosynthesis of distal radial fractures with a volar locking plate: a cadaver study

Background

The purpose of this study was to determine the anatomical features of the pronator quadratus muscle related to minimally invasive plate osteosynthesis for distal radius fractures.

Methods

Ten cadaver forearms were used. The width from the proximal edge to the distal edge of the muscle and the distance from the distal edge of the muscle to the joint surface of the distal radius were measured. After inserting the plate under the pronator quadratus muscle, the distal part of the plate was held over the distal part of the radius and the proximal part of the plate was lifted up from the radius with a fixed locking sleeve. When the pronator quadratus muscle fiber showed signs of tearing, the distance from the volar cortex of the radius to the proximal edge of the plate was measured.

Results

The average width of the pronator quadratus muscle was 35.4 mm. The average distance from the pronator quadratus muscle to the joint surface of the distal radius was 16.6 mm, and the average distance from the cortex to the proximal edge of the plate was 12.2 mm.

Conclusions

The length of the plate should be more than 52 mm to prevent damage to the pronator quadratus muscle. Adjustment of the position of the plate under the muscle should be done in a 12-mm area under the pronator quadratus muscle. The data might provide a useful basis regarding the potential efficacy of minimally invasive plate osteosynthesis for the preservation of pronator quadratus muscle.

     

Thumb reconstruction by the anterior interosseous osteocutaneous retrograde island flap

Summary An original method for thumb reconstruction by the anterior interosseous osteocutaneous island flap is presented. This flap, based on the superior perforating branch of the anterior interosseous artery, is located on the posterior aspect of the forearm, over the distal third of the radius. The dorsal vascular network of the wrist allows the flap to be raised as a retrograde island flap to reach all the parts of the first ray for reconstruction of osteocutaneous loss of the thumb. Two cases have been operated upon successfully with a satisfactory result.     

Wrist denervation and the anterior interosseous nerve: anatomic considerations

PURPOSE: Wrist denervation via resection of the distal anterior interosseous nerve (AIN) and the posterior interosseous nerve (PIN) is an effective treatment for chronic wrist pain. When performing this procedure through a dorsal approach we have been impressed by anatomic variations of the AIN. This has raised concerns about potential denervation of the pronator quadratus (PQ). The purpose of this study was to elucidate the anatomy of the AIN and PIN as encountered through a dorsal distal forearm incision. METHODS: Ten fresh-frozen cadavers were dissected. Before dissection radiographs were obtained to ensure accurate localization of the proximal ulnar head with a radiopaque marker. A dorsal approach to the distal forearm was made to identify the anatomy of the PIN and AIN. The location and diameter of all AIN branches were noted by using an operating stereoscopic microscope at x 25 magnification and a precision caliper. The PIN anatomy and size also were noted. RESULTS: The anatomy of the AIN was variable. The average AIN diameter proximal to the PQ was 1.5 mm. The average number of AIN motor branches was 4.2. The largest PQ motor branch was the first motor branch and was located at an average distance of 37.9 mm from the proximal ulnar head. The last motor branch was found an average of 23.9 mm from the proximal ulnar head. In 9 of 10 specimens the sensory branch tunneled radially through the distal PQ and innervated the periosteum of the volar distal radius. In 4 of 10 specimens a separate branch to the distal radioulnar joint was present. We found an average PIN diameter of 0.87 mm. CONCLUSIONS: Resection of the AIN at a point 4 cm proximal to the proximal point of the ulnar head would denervate completely the PQ in our cadaver population. Division of the AIN 2 cm proximal to the ulnar head would spare most of the PQ motor branches.     

以掌背动脉为蒂尺骨远段背侧骨瓣移位术的应用解剖

目的 为以掌背动脉为蒂的尺骨远段背侧骨瓣移位修复第３、４、５掌骨头缺损提供解剖学依据。方法 在３０侧成人上肢标本上解剖,观察腕背动脉网的构成及分支。结果 腕背动脉网由桡动脉及尺动脉腕背支及与骨间后动脉终末支,骨间前动脉腕背支吻合形成,由该网发生第２、３、４掌背支,第２、３、４掌背动脉由掌背支与掌深弓所发深支吻合而成。结论 以第３、４掌背动脉为蒂的尺骨远端背侧半片骨瓣,可修复第３、４、５掌骨头缺损。     

Pronator quadratus repair using the Henry approach with an outward-return running suture

Repair of the quadratus pronator after osteosynthesis of the distal radius via the Henry approach is generally considered a difficult procedure. The quadratus pronator is a powerful muscle which stabilizes the distal radioulnar joint. The muscle is most often injured in association with distal fracture of the radius. Apposition osteosynthesis appears to be the most appropriate procedure in order to limit loss of reduction, i.e. distal radioular variance, observed in the first postoperative weeks. Tendon complications observed with dorsal approaches and the development of new volar plates with locking screws have offered new prospects for the Henry approach. We propose here a technique for repairing the pronator quadratus with an outward-return running suture using a 2.0 single-strand thread. The technique is designed to redistribute tension along the muscle borders progressively and precisely. Muscle integrity can thus be restored and the flexor system is isolated from the osteosynthesis material.     

改良型骨间背侧动脉岛状皮瓣

目的 介绍一种改良的骨间背侧动脉岛状皮瓣新术式。方法 在骨间背血管暴露段的一条皮支远端设计皮瓣，将皮瓣在该皮支的远端段与骨间背血管主干分离，使原本需在前臂近端设计的皮瓣转向前臂远端设计，从而减小手术切口及防止损伤骨间背神经。结果 9例皮瓣均成活，皮瓣质地良好。结论 该改良型骨间背皮瓣较传统骨间背皮瓣具有减轻手术创伤，减少骨间背神经损伤可能性的优点。     

The Vascular Basis of the Pronator Quadratus Muscle Flap and Its Use in Clinical Cases

Background  Pronator quadratus (PQ) is a deeply situated muscle in the forearm which may occasionally be utilized for soft-tissue reconstruction. The purpose of this anatomical and clinical study was to confirm vascular supply of PQ muscle (PQM) in order to optimize its transfer and confirm its utility in clinical situations. Methods  In Part A of the anatomical study, fresh human cadavers ( n = 7) were prepared with an intra-arterial injection of lead oxide and gelatin solution, and PQM and neurovascular pedicle were dissected ( n = 14). In the anatomical study Part B, isolated limbs of embalmed human cadavers ( n = 12) were injected with India ink-gelatin mixture and PQ were dissected. Results  PQ is a type II muscle flap, with one major pedicle, the anterior interosseous (AI) vessels and two minor pedicles from the radial and ulnar vessels. The mean dimensions of the muscle were 5.5 × 5.0 × 1.0 cm ³ , mean pedicle length was 9.6 cm, and the mean diameter of the artery and the vein was 2.3 mm and 2.8 mm, respectively. The dorsal cutaneous perforating branch (DPB) of the artery supplied the skin over the dorsal forearm and wrist. This branch also anastomosed with the 1, 2 intercompartmental supraretinacular artery (ICSRA). Conclusion  This study confirms the potential utility and vascular basis of the PQM flap and its associated cutaneous paddle. In the clinical part, two patients with nonhealing wounds exposing the median nerve and flexor tendons in the distal forearm were treated using the PQM flap with good results.     

Selective restoration of motor function in the ulnar nerve by transfer of the anterior interosseous nerve. An anatomical feasibility study

BACKGROUND: Proximal ulnar-nerve lesions have an unfavorable prognosis. The goal of the present study was to evaluate the feasibility of selective restoration of motor function of the ulnar nerve by the transfer of the anterior interosseous nerve or one of its branches to the motor branch of the ulnar nerve. METHODS: Ten cadaveric arms were used in the present study. The ulnar nerve and its motor and sensory branches as well as the anterior interosseous nerve and its branches were dissected. The widths of the motor branch of the ulnar nerve and the anterior interosseous nerve and its motor branches as well as the relevant distances from the points of divergence were measured. The axons were counted, and the distances from the end of the main anterior interosseous nerve, its motor branches, and the motor branch of the ulnar nerve to the level of the dorsal sensory branch of the ulnar nerve were measured. RESULTS: Our results indicate that the length, width, and number of axons of the branch of the anterior interosseous nerve to the pronator quadratus make it suitable for transfer to the motor branch of the ulnar nerve. The use of the main anterior interosseous nerve or its motor branches to the flexor pollicis longus and the flexor digitorum profundus is less feasible because of the need to graft a long segment and the longer distance from the level of transfer to the motor end points. CONCLUSIONS: The findings of the present study confirm the feasibility of motor-nerve transfer for reconstruction after an injury of the ulnar nerve. Nerve-grafting would be needed for injuries distal to the level of the dorsal sensory branch of the ulnar nerve.