Curvatures of the DIP joints of the hand

Background

The distal interphalangeal (DIP) joints of the hand are highly susceptible to osteoarthritis and trauma. Surgical treatment options mandate accurate characterization of their osseous anatomy; however, there are few studies that describe this. We describe the curvatures of the DIP joints by measuring the bone morphology using advanced imaging and modeling methods.

Methods

The fingers of 16 right hand fresh frozen human cadavers were analyzed. Fingers showing signs of DIP joint arthritis were excluded. The fingers were scanned using microtomography (microCT). Measurements of the bony morphology were made using models created from the scans.

Results

In each finger, there is no statistically significant difference between the radii of curvature of the ulnar and radial condyles of the middle phalanx head. Conversely, the radius of curvature of the distal phalanx ulnar groove is significantly greater than that of the radial groove. The radii of curvature of the groove of the distal phalanx and the condyles of the middle phalanx displayed nonconformity with disparity increasing from the index to small fingers. Remarkably, the radius of curvature of the distal phalanx central ridge and the mean radius of the middle phalanx condyles are essentially the same.

Conclusion

The purpose of this study is to gain better insight into the DIP joints of the hand. The asymmetry between the distal phalanx grooves and the middle phalanx condyles suggests that there may be a translational component to DIP joint motion. Our understanding of morphology may lend insight into the biomechanics and disease progression within the DIP joints.     

Morphological measurements of the proximal interphalangeal joint

The morphology of the proximal interphalangeal joint was determined using a photographic technique. The head of the proximal phalanx, viewed end on, has a complex trapezoid appearance characteristic for each named digit. The asymmetric condyles diverge from one another and are separated by an intercondylar groove that increases in depth from the dorsal to the palmar surface. Saggital sections of the head of the proximal phalanx are not circular, but, sections taken in the plane of maximum dimensions of the condyle are circular with a radius of curvature of approximately one half of the height of the condyles. The articular surface of the base of the middle phalanx is not circular in outline in either the saggital or coronal plane. In coronal sections the articular surface is biconcave convex with a prominent median ridge separating the two adjacent concave articular surfaces. The implications of this varied morphology on implant design are discussed.     

Simultaneous fracture-dislocations of the distal and proximal interphalangeal joints

Sixteen cases of simultaneous fracture-dislocations of both the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints in the same finger that were treated during the past 10 years were classified into three types: the swan-neck injury (dorsal fragment of the base of the distal phalanx at the DIP joint and palmar fragment of the base of the middle phalanx at the PIP joint); the double-hyperextension injury (palmar fragments at the DIP and PIP joints); and the straight-finger injury (with dorsal and palmar bone fragments at the DIP joint). The results of treatment were more satisfactory in PIP joints than in DIP joints.     

钩骨腕掌关节移位重建指骨间关节的解剖学基础研究

目的探讨钩骨腕掌关节移位、修复和重建手的功能性关节的解剖学基础。方法22侧冷冻成人手腕标本,解剖观测钩骨腕掌关节和中节指骨基底关节面的形态、结构特点,测量各关节面的尺桡径、掌背径、关节面凹面的深度及关节面面积。将所得数据进行统计分析,比较钩骨腕掌关节和中节指骨基底关节面在形态、结构特点、面积及各径线长度的相似度。结果钩骨腕掌关节的尺桡径(13.54mm±1.15mm,钩骨腕掌关节尺桡侧缘中点的距离)和示、中、环指中节与拇指远节指骨基底关节面的尺桡径(关节面尺桡侧缘中点的距离)无统计学差异(P0.01,对应t值分别为2.7670、-2.0720、2.1608、1.2189);钩骨腕掌关节的掌背径(10.71mm±0.93mm,钩骨底嵴的两顶点间距离)和环指中节指骨基底关节面的掌背径(关节面掌背侧缘中点的距离)无统计学差异(P0.01,t=1.6170);钩骨腕掌关节的尺侧凹面深度(1.30±0.08)mm、桡侧凹面深度(0.95±0.05)mm、面积(139.89±5.44)mm2和示、中、环、小指中节指骨、拇指远节指骨基底关节面的凹面深度(尺、桡侧关节面掌背缘中点为支点测量深度)及面积有统计学差异(P0.01)。结论钩骨腕掌关节可作为一个新的良好关节供区,用于修复和重建各中节指骨基底关节面。     

In vitro kinematics of the proximal interphalangeal joint in the finger after progressive disruption of the main supporting structures

Background

Fractures and dislocations of the proximal interphalangeal (PIP) joint of the fingers are among the most common causes of injury in the hand. Objective assessment of the kinematic alterations occurring when the supporting structures are disrupted is critical to obtain a more accurate indication of joint stability.

Methods

An in vitro cadaver model of the hand was used to evaluate the kinematics of the PIP joint in the finger during active unrestrained flexion and extension. The kinematics of the PIP joint following progressive disruption of the main supporting structures was measured using an optical tracking system and compared with those in the intact joint.

Results

Flexion of the intact PIP joint was associated with joint compression, volar displacement, and rotational movements. Release of the main soft-tissue stabilizers and 30 % of volar lip disruption resulted in substantial alteration of several kinematic variables. The normalized maximum dorsal/volar translation was 0.1 ± 1.3 % in the intact group and 14.4 ± 11.3 % in the injured joint.

Conclusions

In the intact PIP joint, rotations and translation are strongly coupled to the amount of joint flexion. Gross instability of the PIP joint occurs when disruption of the collateral ligaments and volar plate is accompanied by resection of at least 30 % of volar lip of the middle phalanx. Collateral ligament injuries, volar plate injuries alone, and fractures at the volar base of the middle phalanx that involve less than 30 % of the articular surface are unlikely to result in gross instability and may be managed effectively with non-operative treatments.     

Silicone arthroplasty for chronic proximal interphalangeal joint dislocations

Chronic dislocations of the proximal interphalangeal (PIP) joint pose a significant treatment challenge. Chronically dislocated PIP joints can experience several changes to the articular cartilage including pressure necrosis, degeneration, and the development of secondary incongruence. Moreover, chronic dislocation allows the edema and hemorrhage from soft tissue trauma to develop into collateral ligament fibrosis and inelastic scar formation. Similarly, chronic dislocations associated with a fracture at the base of the middle phalanx can also experience changes in the form of joint incongruency, bony resorption, or malunion formation. Subsequently, these cumulative joint changes prohibit standard open reduction of the PIP joint and can cause significant loss of motion thereby demanding a different approach to restore motion and minimize pain. We propose the use of silicone arthroplasty in the management of chronic dislocations of the PIP joint.     

Extensor mechanism slide for the treatment of proximal interphalangeal joint extension lag: an anatomic study

PURPOSE: We describe a technique for correction of proximal interphalangeal joint (PIP) extensor lag secondary to angulation and/or shortening of proximal phalanx fractures. METHODS: Proximal phalanx fracture malunions with 2.5 mm of shortening, 5.0 mm of shortening, and apex volar angulation of 40 degrees were simulated in 15 cadaver fingers, creating PIP extensor lags. The metacarpophalangeal (MCP) joint was pinned in neutral. Transection of the ulnar and radial sagittal bands, the extensor digitorum communis (EDC) insertion on the MCP joint capsule, and the juncturae tendinae then was performed. The PIP extensor lag before and after each of the earlier-noted releases was recorded. The MCP joint then was freed and MCP hyperextension was recorded. With the MCP joint in neutral position the sagittal bands then were reapproximated with sutures and MCP extension was measured. RESULTS: The 2.5 mm of axial shortening, 5.0 mm of axial shortening, and 40 degrees of apex volar angulation fracture models produced an average extensor lag of 6.2 degrees , 25.8 degrees , and 42.5 degrees , respectively. Maximal correction of PIP extensor lag required transection of both sagittal bands, EDC insertion on the MCP capsule, and the juncturae tendinae with an average residual extensor lag of -0.8 degrees for the 2.5-mm shortening model, 0.7 degrees for the 5.0-mm shortening model, and 3.2 degrees for the 40 degrees -angulation model. The MCP joint hyperextension increased by 20 degrees to 30 degrees after the releases but decreased to only 1.8 degrees if the sagittal bands were reapproximated to the EDC tendon at their new resting position with the MCP joint in neutral position. CONCLUSIONS: In the cadaver model the PIP extensor lag can be improved substantially by transection of the sagittal bands, release of the EDC insertion on the MCP capsule, transection of the juncturae tendinae, and reapproximation of the sagittal bands to the EDC tendon.     

Arthrodese der Mittel- und Endgelenke der Kleinzehen

Objective

Elimination of the fixed lesser toe deformity by arthrodesis of the proximal or distal interphalangeal joints (PIP and DIP, respectively).

Indications

Painful fixed deformity. PIP joint: fixed hammer toe or clawtoe. DIP joint: fixed mallet toe. Relative indication: flexible hammer toe, clawtoe or mallet toe.

Contraindications

General operative contraindications. Relative contraindications also include severe deformities affecting the metatarsophalangeal (MTP) joint, for which the arthrodesis should combine an operative procedure of the MTP joint.

Surgical techniques

PIP arthrodesis: Dorsal incision centered over the PIP joint, exposure of the PIP joint by transsecting the extensor tendon and joint capsule, release of the collateral ligaments, while carefully protecting the neurovascular bundles, resection of the head of the proximal phalanx and the articular surface of the middle phalanx. The arthrodesis should be stabilised in mild plantar flexion. The tip of the toe should have contact with the surface when the push up test is done. The arthrodesis technique depends on the implant used. The extensor tendon is sutured and the wound is closed. DIP arthrodesis: dorsal incision centered over the DIP joint, exposure of the DIP joint by transsecting the extensor tendon and joint capsule, release of the collateral ligaments, while carefully protecting the neurovascular bundles. Resection of the head of the middle phalanx and the articular surface of the distal phalanx. The arthrodesis should be stabilised in straight position. The arthrodesis technique depends on the implant used. The extensor tendon is sutured and the wound is closed.

Postoperative management

Postoperative full weight bearing for 3–6 weeks, depending on the arthrodesis technique used.

Results

Stabilisation of the toe with adequate alignment is achieved by arthrodesis of the affected joint. In general, digital fusion of the fixed lesser toe pathology shows a high subjective satisfaction rate among the patients, although the rate of pseudarthrosis in attempted PIP or DIP arthrodesis is quite high. Major reasons for postoperative dissatisfaction were swelling, wound necrosis, pin infection, floating toe, shortening and angulation of the toe.     

指固有神经背侧支的应用解剖学研究

目的 为指固有神经背侧支的临床应用提供解剖学基础。方法 观测12只新鲜成人手标本48个手指指固有神经背侧支出的出现率、直径、走向及分支。结果 示、中、环指及小指桡侧指固有神经发出的单一分支形成背侧支者占92．86％（78．84）,背侧支缺如者占7．14％（6．84侧）。各指背侧支均在近节手指近、中1／3平面发出,并从指侧面斜向指背远端走行。在近指间关节桡背（或尺背）侧向背面及中节指背发出2－5条分支。除小指外,2－4指指桡、尺侧背侧支的直径粗细均有显著性差异（P＜0．05）,桡侧＞尺侧。小指飞侧无指固有神经背侧支。结论 示、中、环及小指的桡侧指固有神经背侧支走向恒定,可包含在同指逆行岛状皮瓣内,适用于修复指腹软组织缺损。     

Brachydactyly type C

Brachydactyly type C is an autosomal dominant disorder with markedly variable penetrance. A patient with limited gene expression has shortening limited to the middle phalanges and the first metacarpal and an elongation of the radial side of the base of the second proximal phalanx. When completely expressed the characteristic radiographic findings are shortening of all the metacarpals, greatest in the thumb, followed by the little, ring, middle, and index fingers; brachymesophalangy (shortening of the middle phalanges); shortening of the proximal phalanges of the index and middle fingers, with the proximal phalanges of the ring and small fingers of normal length; elongation of the radial side of the base of the second proximal phalanx resulting in a trapezoidal shaped epiphysis; ulnar deviation at the second and third metacarpophalangeal joints; and hypersegmentation (extra phalanx) of the index and middle fingers. The ulnar deviation of the index and middle fingers may result in scissoring and require surgical correction. The hand deformities of 10 patients with brachydactyly type C are presented to characterize the hand abnormalities in the syndrome and its variable presentation.     

Quantifying the effect of the distal intrinsic release procedure on proximal interphalangeal joint flexion: a cadaveric study

PURPOSE: The distal intrinsic release procedure is a popular treatment for intrinsic hand tightness. The literature remains ambiguous regarding the optimal amount of extensor hood to excise. Our goals were to quantify the mathematic relationship between the amount of extensor hood excised and proximal interphalangeal (PIP) joint flexion and to determine the minimum amount of extensor hood excision required to significantly change PIP joint flexion capability (the ability to achieve a change from the initial PIP joint angle). METHODS: We simulated the distal intrinsic release procedure by sequentially excising 5-mm strips (perpendicular to the long axis of the finger) of the extensor hood of cadaveric fingers beginning 5 mm proximal to the PIP joint center. We tensioned the intrinsic muscles to each digit to produce an intrinsically tight state and tensioned the flexor digitorum superficialis to produce an antagonist force and simulate the intrinsic tightness test. We measured PIP joint angle (the angle of the long axis of the middle phalanx relative to the proximal phalanx) in response to greater portions of excised extensor hood to quantify its contribution to intrinsic tightness. RESULTS: The relationship between the amount of extensor hood excised and the PIP joint flexion capability appeared quadratic, not linear. For the index, ring, and small fingers significant changes in PIP joint flexion were detected after resection of 59%, 26%, and 33%, respectively, of the extensor hood length. Although our results did not show statistical significance for the middle finger we project the critical amount to be at least 65%. CONCLUSIONS: We show PIP joint flexion changes after the distal intrinsic release procedure. We recommend excising a finger-dependent minimum amount of tissue before expecting a significant increase in PIP joint flexion capability.     

The use of skeletal extension torque in reversing Dupuytren contractures of the proximal interphalangeal joint

Dupuytren contracture of the proximal interphalangeal (PIP) joint can be reversed by an extension torque transmitted from an external device, the Digit Widget, by skeletal pins to the middle phalanx. This extension torque, generated by the same elastic bands dentists use to align teeth, gradually restores length to soft tissues palmar to the PIP joint's axis of rotation. Simultaneously, tissues dorsal to the joint's axis will shorten toward normal length as the PIP progressively straightens. Although the contractile nodules and bands of Dupuytren disease may be excised either before or after reversal of the joint's contracture, a 2-staged approach is preferred: (1) reverse the PIP flexion contracture, and (2) excise the diseased tissue from the straightened finger. We believe this 2-staged approach yields better results. In addition, it is technically easier to avoid injury to nerves and arteries while excising the nodules and bands, when one operates through palmar skin of more nearly normal length.     

Autologous osteoarticular transfer from the proximal tibiofibular joint to the scaphoid and lunate facets in the treatment of severe distal radial fractures: a report of two cases

PURPOSE: This study was conducted to determine the appropriateness of using the articular cartilaginous surfaces of the proximal tibiofibular joint to resurface damaged distal radial articular surfaces and to assess the clinical results in the first 2 patients. METHOD: Cadaveric specimens of the facets of the proximal tibiofibular joints and distal radius were sized and compared. Two patients underwent transfer of a fibular facet. RESULTS: The surface area of each of the proximal tibiofibular facets were larger than either the scaphoid or lunate facets of the distal radius. The 2 patients had excellent clinical results with minimal donor morbidity. CONCLUSIONS: Use of the articular surfaces from the proximal tibiofibular joint to replace damaged distal radial facets is possible and can be accomplished with excellent results and minimal morbidity.     

The treatment of an osteochondral shearing fracture-dislocation of the head of the proximal phalanx: a case report

We report the morphology and treatment of a proximal interphalangeal joint dislocation resulting in an injury to the articular surface of the proximal phalanx and avulsion of the radial collateral ligament from its proximal origin. A large osteochondral fragment was sheared from the radial articular surface of the proximal phalanx and remained displaced volarly after reduction of the joint. Plain radiographs and 2- and 3-dimensional computed tomography images were used to evaluate this unusual injury before surgery. Open reduction and internal fixation using a small K-wire and figure-of-eight wire technique restored the articular surface of the head of the proximal phalanx and gave a satisfactory functional result.     

The terminal tendon of the digital extensor mechanism: Part I, anatomic study

PURPOSE: The purpose of this study was to examine the anatomy of the terminal tendon (TT) and its relationship to adjacent structures. MATERIALS: The extensor tendons of 56 cadaveric digits (52 fresh-frozen and 4 formalin-preserved) underwent anatomic dissection. RESULTS: The TT is a segment between the convergence of the lateral bands proximally and the bony insertion in the phalanx distally. The ulnar lateral bands were thicker than the radial bands. The average distance from the TT insertion to the germinal matrix of the nail bed was 1.4 mm. The triangular ligament (TL) is a thin layer of transverse fibers between the lateral bands proximal to the TT. The dimensions of the TT and the TL vary relative to the size of the digit with the largest often occurring in the middle, followed by the ring, index, and small finger. The transverse retinacular ligament (TRL) had a dorsal attachment to the lateral bands and was much more defined and distinct than the oblique retinacular ligament. The ulnar TRL often was thicker than the radial TRL. CONCLUSIONS: The TT is the primary structure responsible for extending the distal interphalangeal (DIP) joint. The function of the adjacent retinacular structures is to provide stability to the TT. The thin nature and proximity of the TT to the nail matrix must be kept in mind during surgery. Knowledge of the TT anatomy is necessary for further study of its kinematics and pathology and for diagnosis and management of its disorders.     

Dorsal fracture dislocations of the proximal interphalangeal joint treated by open reduction and interfragmentary screw fixation: indications, approaches and results

Many operative and non-operative treatments of dorsal fracture dislocations of the proximal interphalageal (PIP) joint have been described. Return of good joint function requires anatomical reduction of the articular fragments and restoration of joint congruity and a stable functional arc of motion, with the fixation construct stable enough for early mobilization. To prevent recurrent dorsal subluxation, the attachments of the ligamentous palmar restraints and the bony buttress provided by the palmar lip of the middle phalanx base must be restored. Open reduction and internal interfragmentary screw fixation using 1.5 or 1.3mm screws was employed in 12 fingers in 10 patients with unstable dorsal fracture dislocations of the PIP joints of Schenck grades III and IV. At an average follow-up of 8.7 months, all patients in this series achieved good to excellent results and an average total active interphalangeal motion of 132 degrees (range 105 degrees -165 degrees). Additional benefits over non-operative techniques included improved patient comfort and simplified nursing care and therapy supervision.     

Metacarpophalangeal arthroscopy.

Although small joint arthroscopy has become commonplace over the past decade, relatively little attention has been paid to the investigation and clinical utility of metacarpophalangeal (MP) joint arthroscopy. The literature is scant in this area and consists of only a handful of case reports. In addition, the arthroscopic anatomy of the MP joint has not as yet been reported. Six cadaveric hands (24 joints) were rigorously studied in the laboratory using standard 2.5-mm small joint arthroscopic instrumentation and 5 lb of overhead traction. Radial and ulnar portals were used with care not to injure the extensor tendons. Arthroscopic anatomic landmarks include: (1) A consistent tripartite configuration of the main radial and ulnar collateral ligaments with characteristic changes in relative fiber orientation as the digit goes from extension to flexion, (2) nonvisualization of the accessory collateral ligament from inside the joint, (3) transitional amorphous capsular fibers connecting the collateral ligaments to the volar plate and dorsal capsule, (4) four synovial recesses (radial, ulnar, volar, and dorsal-proximal), (5) metacarpal head and proximal phalanx, (6) a consistent circumferential meniscal equivalent around the margin of the proximal phalanx articular surface, and (7) the sesamoid-metacarpal articulation in the thumb MPjoint. There are published case reports on the utility of MP joint arthroscopy for synovectomy in rheumatoid arthritis and hemachromatosis and realigning Stener lesions in gamekeepers' thumbs. The current clinical series reveals preliminary experience with the technique. MP joint arthroscopy was useful in relieving a locked MP joint from a loose osteochondral body and sagittal tear in the volar plate that enfolded into the joint surface. Intra-articular release of post-traumatic volar plate and dorsal capsular contracture were readily accomplished using this technique. Juxta-articular bone lesions such as osteoid osteomas can be removed with careful preoperative planning. Gamekeeper's thumbs that are unstable on stress radiographs can undergo arthroscopy with excellent sensitivity to determine the presence of a Stener lesion before an open or arthroscopic repair. The advantages of arthroscopic versus open techniques are similar to those experienced in larger joints. With time, more indications will emerge.     

The dorsal approach to silicone implant arthroplasty of the proximal interphalangeal joint

Silicone implant arthroplasty (SIA) has been an effective alternative in the treatment of arthritic conditions of the proximal interphalangeal (PIP) joints since its introduction into surgical practice in the early 1960s. Patients with post-traumatic, degenerative, and rheumatoid arthritis all may be candidates for PIP joint SIA. The indications for SIA of the PIP joint include pain, limited joint mobility, and angular deformity of the joint with underlying articular destruction. Contraindications include ankylosis of the joint due to bony or soft-tissue restrictions, infection, inadequate soft-tissue support for coverage, absence of flexor and/or extensor tendon function, and considerable periarticular bone loss in the proximal and middle phalanges. Proximal interphalangeal joint SIA can be accomplished by dorsal, volar, or midaxial approaches. The dorsal approach has the advantages of relative technical ease, excellent visibility of the articular surfaces for preparation of the implant canals, access to the extensor mechanism for correction of central slip abnormalities, and preservation of the collateral ligaments. The surgical technique is outlined and includes handling of the extensor mechanism and central slip attachment, mobilization of the collateral ligaments, joint surface resection, preparation of the bony canals, implant sizing, implant insertion, and repair of the soft tissues. Pearls and pitfalls of the technique are outlined. Early postoperative mobilization with hand therapy is essential but must include protection of the repaired extensor apparatus. Complications include bony changes, implant failure, recurrent angular deviation or swan-neck deformity, particulate synovitis, and rarely, infection. Complications related to implant failure are most often managed with implant replacement or arthrodesis; those related to poor mobility, angular deformity and tendon imbalance, pain, or infection are managed by arthrodesis. Although SIA of the PIP joint has a relatively high degree of success when measured both subjectively and objectively, careful patient selection is important for achieving desirable results.     

The human first carpometacarpal joint: osteoarthritic degeneration and 3-dimensional modeling.

The purpose of this study was to gain insight into potential mechanical factors contributing to osteoarthritis of the human first carpometacarpal joint (CMC). This was accomplished by creating three-dimensional (3-D) computer models of the articular surfaces of CMC joints of older humans and by determining their locus of cartilage degeneration. The research questions of this study were: 1) What is the articular wear pattern of cartilage degeneration in CMC osteoarthritis?, (2) Are there significant topographic differences in joint area and contour between the joints of males and females?, and 3) Are there measurable bony joint recesses consistently found within the joint? The articular surfaces of 25 embalmed cadaveric joints (from 13 cadavers) were graded for degree of osteoarthritis, and the location of degeneration was mapped using a dissection microscope. The surfaces of 14 mildly degenerated joints were digitized and reconstructed as 3-D computer models using the Microscribe 3D-X Digitizer and the Rhinoceros 2.0 NURBS Modeling Software. This technology provided accurate and reproducible information on joint area and topography. The dorsoradial trapezial region was found to be significantly more degenerated than other quadrants in both males and females. Mean trapezial articular surface area was 197 mm 2 in males and 160 mm(2) in females; the respective mean areas for the metacarpal were 239 mm(2) in males and 184 mm(2) in females. Joints of females were found to be significantly more concave in radioulnar profile than those of males. Three bony joint recesses were consistently found, two in the radial and ulnar aspects of the trapezium and the third in the palmar surface of the metacarpal.