The extensor retinaculum of the wrist: an anatomical and biomechanical study

Through an anatomical and biochemical study, utilizing sixty-five cadaver specimens, the extensor retinaculum of the wrist was examined. It is a complex variable fibrous structure, whose functions are to prevent dorsal bowstringing of the extensor tendons and to prevent radial and ulnar displacement of extensor tendons. We recommend that a portion of the extensor retinaculum be preserved or reconstructed at the time of dorsal wrist surgery.     

An anatomic and biomechanic study of the wrist extensor retinaculum septa and tendon compartments

PURPOSE: The anatomy of the extensor retinaculum of the wrist has been described previously; the purpose of this study was to describe the specific anatomy of the septal attachments on the radius and to investigate the mechanical strength of each septal attachment on the radius and each of the 6 compartments of the extensor retinaculum. METHODS: Thirty-four wrists from 24 fresh-frozen and 10 embalmed cadavers were used. First, anatomic measurements of the individual extensor retinaculum septums were performed with calipers and a 3-dimensional digitizer. Next each extensor retinaculum septum was excised as a bone-retinaculum-bone autograft and was tested in tension to failure with a materials testing machine. Finally the 6 extensor retinaculum compartments were tested to failure. RESULTS: Septum 1/2 had the largest radial surface area and septum 3/4 had the smallest. Septum 1/2 also was found to have the highest failure strength at 51.3 +/- 15.3 N. In compartment testing, compartments 1 and 2 had the highest overall resistance to failure and compartment 5 had the lowest. Compartment 6, which was thought to be the weakest because of clinically observed subluxation of the extensor carpi ulnaris tendon, had stronger failure data than expected. CONCLUSIONS: This study offers detailed analysis of the extensor retinaculum compartments and 3-dimensional anatomy of the septal attachments. Clinically this study lends insight to the strength of bone-retinaculum-bone autografts and the etiology of extensor carpi ulnaris subluxation.     

Reconstruction of pulleys employing extensor retinaculum.

In ten cases, including five rod placements, four tenolyses, and one immediate tendon graft, 15 pulleys have been reconstructed using a strip of extensor retinaculum 6 to 8 cm long and 8 mm in width. Placed around the phalanx, overlapped, and sutured, the 15 mm segment formely over the fourth dorsal compartment has been positioned over the flexor tendod. The reconstruction has been shown to be stronger than the 10 figure-of-eight No. 4-0 sutures employed to perform it and capable of withstanding immediate active motion. No impairment, functional or cosmetic, of the extensor apparatus has been observed.     

Complications of extensor tendon repairs at the extensor retinaculum

Literature describing surgical, post-operative management and outcomes following EDC repairs in close proximity to or within the extensor retinaculum is limited. This complex injury can result in decreased wrist and digital motion as well as loss of independent motion of the digits. This paper reviews complications following such injuries observed clinically as well as experimental simulation performed on cadaveric specimens. Our observations have direct implications to hand therapy practice and outcomes used following such injuries.     

腕背伸肌支持带筋膜瓣在桡骨远端骨折背侧入路中的应用

目的：探讨腕背伸肌支持带筋膜瓣在桡骨远端骨折背侧入路中的临床应用。方法选择2010年6月至2015年6月我院收治的桡骨远端骨折需行背侧入路固定病人120例。按照就诊的先后顺序采用数字表法将病人随机分为两组,筋膜瓣组52例病人骨折复位固定后采用腕背伸肌支持带筋膜瓣对拇长伸肌腱进行转位,常规手术组68例病人仅采用常规骨折复位固定手术。术后随访观察并比较两组病人拇长伸肌腱并发症的发生率。结果本组120例病人均手术成功,均获得随访,随访时间为3~60个月（平均为16.2个月）。筋膜瓣组未出现肌腱并发症;常规手术组发生3例拇长伸肌腱炎,1例拇长伸肌腱断裂,肌腱并发症发生率为5.88%。筋膜瓣组的肌腱并发症发生率明显低于常规手术组,差异有统计学意义（P=0.075）。结论与掌侧入路钢板置入治疗桡骨远端骨折相比,背侧入路钢板置入固定后的肌腱并发症发生率较高,腕背伸肌支持带筋膜瓣可以很好地避免这一并发症,并且操作简单,值得推广使用。     

Impingement of a fibroma of the extensor tendon sheath on the extensor retinaculum

Deep lacerations to the forearm can cause impaired movement of the digits. This report describes the presentation and management of a self-harmer who presented with loss of motion of her ring finger. Surgical exploration unexpectedly demonstrated the cause to be a fibroma of the tendon sheath impinging on the extensor retinaculum. Full recovery was demonstrated at sixmonth review following removal of the lesion.     

Importance of the reconstruction of the extensor retinaculum after injury

We reconstructed an extensive soft tissue defect of the dorsum of the left wrist after an injury using a free anterolateral thigh flap and a tendon graft, and intending to substitute the extensor retinaculum for the fascia in this flap. As a result, maximum function of the extension mechanism was restored to the reconstructed hand.     

Measurement of gliding resistance of the extensor pollicis longus and extensor digitorum communis II tendons within the extensor retinaculum

PURPOSE: The etiology of spontaneous extensor pollicis longus (EPL) tendon rupture is still largely unknown. It is possible that friction within the sheath may play a role. The purposes of this study were to compare gliding resistance of the EPL tendon with that of the extensor digitorum communis tendon of the index finger (EDC II) and to find the wrist position that gives the EPL tendon the lowest gliding resistance. METHODS: Fifteen fresh-frozen cadavers were used. Gliding resistance was measured directly in 7 different wrist positions. RESULTS: The mean gliding resistance of the EPL tendon was 0.16 +/- 0.08 N and that of the EDC II tendon was 0.11 +/- 0.06 N. This difference was significant. There was also a significant effect on gliding resistance due to wrist position. For the EPL tendon, the gliding resistance was significantly greater in 60 degrees wrist flexion compared with all other wrist positions tested. Additionally the gliding resistance of the EPL in 30 degrees flexion, 60 degrees extension, and 15 degrees radial deviation was significantly higher than wrist positions of 30 degrees extension, neutral, and 30 degrees ulnar deviation. CONCLUSIONS: Positioning the wrist close to neutral flexion/extension and in some ulnar deviation minimizes the friction within the EPL sheath. Such positions may be advantageous for splinting patients at risk for EPL rupture.     

Role of peripatellar retinaculum in transmission of forces within the extensor mechanism

BACKGROUND: The role of the peripatellar retinaculum as a frontal plane stabilizer of the patellofemoral joint has been well established. However, as a result of its unique orientation, the retinaculum also may influence the distribution of forces within the extensor mechanism. The objective of this study was to determine the extent to which the peripatellar retinaculum affects the magnitude of forces experienced by the patellar tendon. METHODS: Ten cadaver knees were used in this investigation. Each was mounted on a custom test apparatus that was fixed to an Instron frame. The extensor mechanism was loaded by applying forces through the individual heads of the quadriceps femoris. Patellar tendon tension was measured at 0 degrees , 20 degrees , 40 degrees , and 60 degrees of knee flexion with use of a buckle transducer under two conditions: (1) with the peripatellar retinaculum intact, and (2) with the peripatellar retinaculum removed. Patellar tendon tension was compared between the two conditions across the knee flexion angles. RESULTS: At each knee flexion angle, the patellar tendon tension was greater with the retinaculum removed than it was with the retinaculum intact. However, the difference was significant only at 0 degrees and 60 degrees , at which positions the force transmitted to the patellar tendon was increased by 16.6% and 9.6%, respectively. Conclusions: The observed increases in patellar tendon tension after removal of the peripatellar retinaculum is an indication of the load-sharing function of that structure as a part of the extensor mechanism. CLINICAL RELEVANCE: Our results suggest that compromise of the peripatellar retinaculum may alter patellar tendon and/or patellofemoral joint forces.     

Length change patterns of the extensor retinaculum and the effect of total knee replacement

Patellofemoral dysfunction following total knee replacement (TKR) is a significant clinical problem, but little information exists on the mechanics of the patellofemoral retinacula or the effects of TKR on these structures. We hypothesized that TKR would cause significant elongation of the retinacula. Retinacular length changes were measured by threading sutures along the retinacula, fixing the sutures to the patella and the iliotibial band (ITB), and attaching the femoral ends to displacement transducers. The intact knee was flexed‐extended while the quadriceps and ITB were tensed and the retinacular length change patterns were recorded. The measurements were repeated post‐TKR. The medial patellofemoral ligament (MPFL) was close to isometric, stretching 2 mm in terminal knee extension, whereas the lateral retinaculum slackened 8 mm from 110° to 0° flexion. TKR did not cause significant elongation of either of the retinacula, the largest change being 3 mm elongation of the MPFL around 40°, which stretched the MPFL by 1.4 mm above its maximum natural length. Thus, this work did not support the hypothesis that TKR causes significant elongation of the retinacula sufficient to affect knee function. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 865–870, 2009     

Coccidioidomycosis of the extensor tenosynovium of the wrist. A case report

A 59-year-old man had isolated coccidioidomycosis infestation of the tenosynovium of the wrist extensor tendons resistent to surgical and amphotericin chemotherapy. Some improvement has been noted on Miconazole chemothearapy, but neither the long term side effects nor clinical results are known.     

Decompression of the extensor tendons at the wrist in rheumatoid arthritis.

Simple decompression of the extensor tendons at the wrist was carried out on fifty-four wrists in a total of forty-one patients with rheumatoid disease. This procedure was combined with excision of the ulnar head in forty-five wrists. Complete resolution of the synovitis occurred in 81.5 per cent of the wrists. In two patients the tendons ruptured soon after operation and in both cases this was due to prolapse of the ulnar stump after an associated Darrach procedure. The clinical results of decompression compare favourably with those of the widely accepted operation of dorsal tenosynovectomy.     

Functional outcomes following surgical repair of wrist extensor tendons.

The long term results following the repair of open injuries to extensors carpi radialis longus and brevis and extensor carpi ulnaris have not previously been reported. A retrospective case note review was performed and patients were called back for assessment following surgical repair. Grip strength and pinch strength were reduced by 9.9% (p=0.017) and 11.5% (p=0.049). Wrist movement was also reduced. This demonstrates that the division of these tendons should not be regarded as trivial as they may have long-term adverse effects on wrist function. Information gained from this study may be beneficial in patient education at the time of injury and may provide useful information when preparing medico legal reports.     

The effect of femoral component rotation on the extensor retinaculum of the knee

Malrotation of the femoral component may cause patellofemoral complications after total knee replacement (TKR). We hypothesized that femoral component malrotation would cause excessive lengthening of the retinacula. Retinacular length changes were measured by threading fine sutures along them and attaching these to the patella and to displacement transducers. The knee post‐TKR was flexed‐extended while the quadriceps were tensed, then the measurements repeated after rotating the femoral component 5° internally and then 5° externally. Internal rotation shortened the medial patellofemoral ligament (MPFL) significantly from 100° to 0° extension. External rotation lengthened the MPFL significantly from 90° to 0° extension. The transverse fibers of the lateral retinaculum showed no significant differences. The MPFL attaches directly from bone to bone, so it was lengthened directly by movement of the trochlea and patella, whereas the deep transverse fibers of the lateral retinaculum attach to the mobile iliotibial tract, so they were not lengthened directly. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1136–1141, 2010     

Architecture of selected wrist flexor and extensor muscles

The architectural features of 25 wrist flexor and extensor muscles were studied. Muscles included the flexor carpi ulnaris, the flexor carpi radialis, the extensor carpi ulnaris, the extensor capri radialis brevis, and the extensor carpi radialis longus. Muscle length, mass, fiber pennation angle, fiber length, and sarcomere length (by use of laser diffraction techniques) were determined. In addition, physiological cross-sectional area and fiber length/muscle length ratio were calculated. The muscles were found to be highly specialized, with architectural features of same muscles very similar. The fiber length/muscle length ratio, muscle length, and pennation angle represented the major differences between muscles. Thus using these parameters in discriminant analysis permitted correct identification of each of the 25 muscles. In terms of size and intrinsic design, these individual muscles were highly specialized for their function.     

Anatomy of the flexor retinaculum of the wrist and the flexor carpi radialis tunnel

The flexor retinaculum forms a retinacular bridge over the carpal tunnel extending from ulnar to radial direction. Its main function is to protect the contained without a significant mechanical action in supporting the transverse carpal arch. The osteofibrous tunnel of flexor carpi radialis is independent and presents four sections. The palmaris longus tendon presents a distal insertion forming the superficial layer of the aponeurosis palmaris. The flexor carpi ulnaris tendon has four distal insertions.