Lateral stability of the proximal interphalangeal joint

Proximal interphalangeal joint dislocations and fracture-dislocations

Although proximal interphalangeal joint dislocations are generally straightforward to treat, fracture-dislocations are among the most difficult hand injuries to manage. Fracture patterns range from simple to treat palmar plate avulsion fractures to complex, unstable pilon fractures of the base of the middle phalanx, where achieving adequate reduction and fixation can be extremely difficult. Moreover, these fractures may present sub-acutely or chronically, which greatly adds to the complexity of the case. It is therefore no surprise that clinical results vary and are often difficult to predict. We will discuss the clinical presentations, the various dislocation and fracture-dislocation patterns, treatment options and the complications of these injuries.

Proximal Interphalangeal Joint Congruity: A Biomechanical Study

BACKGROUND

Surgical approaches to the proximal interphalangeal (PIP) joint often require disruption of soft tissue stabilizers. Additionally, PIP joint injuries frequently result in soft tissue disruption. This study evaluates the necessity of repairing soft tissue stabilizers by assessing their role in maintaining native joint congruity.

METHODS

Eight specimens were used to evaluate congruity at 0° and 30° flexion when loaded with 2 N of valgus force. This was performed in the native joint and after sequential sectioning of the surrounding ligaments in order: volar plate (VP), radial collateral ligament (CL), and ulnar CL. The skin flap was sutured with the ligaments unrepaired and the load was reapplied. Radiographs were taken after each load and used to measure the joint line convergence angle (JLCA).

RESULTS

Mean JLCA increased in both degrees of flexion after ligaments were sectioned but was only significantly different from the native joint after the VP was disrupted along with 1 CL. Joint congruity improved following repair of the skin flap in both degrees of flexion but was not significant. Joints were more congruent in 30° flexion for all subgroups, but none were significantly different compared to 0° flexion.

CONCLUSIONS

Disruption of the VP is insufficient to significantly alter PIP joint congruity. While sectioning of both the VP and CLs resulted in a statistically significant change in joint congruity, mean JLCA demonstrated changes of minor clinical significance. The osseous anatomy of the phalanges imparts inherent stability that maintains a congruent joint despite loss of the soft tissue stabilizers.

Radioulnar interphalangeal joint angles in children and adolescents aged 0 to 19 years

The purpose of this study is to determine the normal ranges of radioulnar (i.e. medial-lateral) finger deviations during growth. We retrospectively measured radioulnar interphalangeal joint angles in 6236 properly aligned thumbs and fingers in trauma radiographs of 4720 patients aged 0 to 19 years. The mean interphalangeal joint angle of the thumb was 0.2° (standard deviation 1.5°). The average proximal interphalangeal joint angles were ulnar deviation of 2.5° (1.7°) for the index, ulnar deviation 1.7° (1.5°) for the middle, radial deviation 1.3° (1.8°) for the ring, radial deviation 2.0° (2.8°) for the little fingers. The distal interphalangeal joint angles were ulnar deviation of 2.5° (1.7°), ulnar deviation 2.1° (1.7°), radial deviation 2.1° (1.7°), radial deviation 5.1° (2.8°) from index to the little fingers. Thumbs were typically straight, whereas the index and middle fingers deviated ulnarly, and ring and little fingers radially. There were no relevant differences in sex or laterality.

The Importance of Restoring Anatomy of the Proximal Interphalangeal Joint in Dorsal Fracture Dislocations

The proximal interphalangeal joint (PIPJ) is a complex anatomical structure. In managing fracture dislocations about the PIPJ, the aim is to restore a congruent joint that allows for smooth gliding motion. Detailed knowledge of the anatomy and biomechanics of the PIPJ is necessary in managing these injuries with predictable success. The breadth of techniques previously described in the treatment of such injuries is testament to the difficulties faced in achieving optimal clinical and radiological outcomes. In this article we detail the anatomy and biomechanics of the PIPJ and summarize current literature and principles for the treatment of dorsal fracture dislocations.

Use of a Costal Osteochondral Graft for Reconstruction of a Proximal Phalanx Head with a Comminuted Fracture of the Proximal Interphalangeal Joint

We report the use of costal osteochondral grafting with a pins and rubbers traction system (PRTS) for treatment of a complex cartilage defect of the proximal interphalangeal (PIP) joint in a 41-year-old male carpenter who had inadvertently incompletely severed his finger with a power saw. The skin laceration extended to the dorsal aspect of his ring finger and resulted in incomplete loss of the ulnar condyle and comminution of the radial condyle of the proximal phalanx of the PIP joint. The diagnosis was intra-articular PIP joint open fracture of the left ring finger with a 60% defect of the proximal phalanx joint surface. Three weeks after the injury, PIP joint reconstruction was performed with a costal osteochondral graft harvested at the osteochondral junction of the fifth rib. The volar side of the proximal phalanx cortex and the condyles of the proximal phalanx on each side, which included the origin of the collateral ligaments, were preserved. The graft was shaped to match the defect, and biplane fixation with three miniscrews was subsequently performed. Last, a PRTS was attached. At 6 months postoperatively, the patient returned to his job; at 12 months postoperatively, the joint was stable and free of pain. This technique enabled preservation of joint stabilizers and rigid fixation of the graft, resulting in a good outcome. Our modified costal osteochondral graft with a PRTS is useful for severe intra-articular fractures of the PIP joint and should be considered before salvage procedures.

Volar plate avulsion fracture alone or concomitant with collateral ligament rupture of the proximal interphalangeal joint: A comparison of surgical outcomes

Background

Volar plate avulsion fracture of the proximal interphalangeal (PIP) joint is one of the most common hand injuries. In this study, we divided patients into two groups: patients with pure volar plate avulsion fracture, and patients with volar plate avulsion fracture concomitant with collateral ligament rupture. The purpose of this study was to compare long-term surgical outcomes between the two groups. As a secondary measure, the Mitek bone anchoring and polydioxanone (PDS) bone suturing techniques were compared.

Methods

A single-institutional retrospective review of the surgical treatment of volar plate avulsion fracture was performed. The cases were divided into those with pure volar plate avulsion fracture (group A, n=15) and those with volar plate avulsion fracture concomitant with collateral ligament rupture (group B, n=15). Both groups underwent volar plate reattachment using Mitek bone anchoring or PDS bone suturing followed by 2 weeks of immobilization in a dorsal protective splint.

Results

The average range of motion of the PIP joint and extension lag were significantly more favorable in group A (P<0.05). Differences in age; follow-up period; flexion function; visual analog scale scores; disabilities of the arm, shoulder, and hand scores; and the grip strength ratio between the two groups were non-significant. No significant differences were found in the surgical outcomes of Mitek bone anchoring and PDS bone suturing in group A.

Conclusions

Overall, the surgical outcomes of volar plate reattachment were successful irrespective of whether the collateral ligaments were torn. However, greater extension lag was observed in cases of collateral ligament injury.

Anatomy and Biomechanics of the Finger Proximal Interphalangeal Joint

A complete understanding of the normal anatomy and biomechanics of the proximal interphalangeal joint is critical when treating pathology of the joint as well as in the design of new reconstructive treatments. The osseous anatomy dictates the principles of motion at the proximal interphalangeal joint. Subsequently, the joint is stabilized throughout its motion by the surrounding proximal collateral ligament, accessory collateral ligament, and volar plate. The goal of this article is to review the normal anatomy and biomechanics of the proximal interphalangeal joint and its associated structures, most importantly the proper collateral ligament, accessory collateral ligament, and volar plate.

Treating Proximal Interphalangeal Joint Dislocations

Proximal interphalangeal (PIP) joint dislocation a common injury. Usually, concentric stable reduction can be achieved with closed reduction. Occasionally, PIP joint dislocations are irreducible and open reduction is necessary. Complications include prolonged splinting and delay in presentation with subluxation or persistent dislocation. Surgery is often recommended for contracture or joint reduction. Surgical techniques focus on contracture release, joint reduction, and range of motion. Techniques have evolved from primary repair to tenodesis and suture anchor reconstruction. Most studies on PIP joint dislocations are retrospective case reports with good outcomes but chronic mild contracture and deformity are consistent in the literature.

Complications of Proximal Interphalangeal Joint Injuries: Prevention and Treatment

Proximal interphalangeal joint injuries are one of the most common injuries of the hand. The severity of injury can vary from a minor sprain to a complex intra-articular fracture. Because of the complex anatomy of the joint, complications may occur even after an appropriate treatment. This article provides a comprehensive review on existing techniques to manage complications and imparts practical points to help prevent further complications after proximal interphalangeal joint injury.

Results of the Volar Approach in Proximal Interphalangeal Joint Arthroplasty

Background: Most hand surgeons use a dorsal approach for proximal interphalangeal (PIP) joint implant arthroplasty. However, a volar approach offers the advantage of no disturbance to the extensor mechanism, thus allowing early initiation of active range of motion. We examined our results in patients who underwent PIP joint arthroplasty via a volar approach.

Methods: Using a retrospective chart review, we evaluated the outcomes of patients undergoing PIP joint arthroplasty through a volar approach between 2001 and 2005 by 3 fellowship-trained hand surgeons at our institution. The indication for surgery was PIP joint pain with radiographic evidence of joint destruction. Variables included implant type, diagnosis, affected digit(s), preoperative and postoperative range of motion, and complications. Hand therapy was initiated on postoperative day 3 or 4.

Results: Over the 5 years, 25 PIP joints were replaced in 18 women and 2 men with the volar approach. Replacements consisted of 14 surface replacement prostheses, 9 pyrocarbon prostheses, and 2 silicone prostheses. The average age of patients at prosthesis implantation was 64 years (range, 39–75 years). Prostheses were placed in 1 index, 12 long, 7 ring, and 5 small digits. Average follow-up period was 33 months (range, 24–69 months). Preoperative diagnoses were osteoarthritis (14), rheumatoid arthritis (4), and posttraumatic arthritis (2). Preoperative total arc of motion averaged 42° (range, 0° extension to 80° flexion); postoperative total arc of motion averaged 56° (range, –10° extension to 90° flexion). Complications comprised 1 swan neck deformity, 1 deep infection, 1 dislocation (early), and 2 loose implants with flexion contractures. Seventeen patients had minimal or no pain at their last follow-up visit.

Conclusions: PIP joint arthroplasty can be successfully implemented through a volar approach with various implant types and has outcomes similiar to the published results of the dorsal approach.

[Ligamentous lesions and instability of the finger joints]

Joint capsule and ligamentous lesions are common injuries of the upper extremities. Athletes are particularly inclined to suffer from these injuries. Clinical and radiological examinations are the cornerstone of an adequate treatment. Ultrasound-based diagnostics as a non-invasive and dynamic investigation method are gaining increasing relevance based on the development of high resolution probes. A correct interpretation of the findings is only feasible with a comprehensive knowledge of the anatomy. The most important goal is stability as a prerequisite for early active and passive motion with unrestricted range of motion.

The Collateral Ligament of the Digits of the Hand: Anatomy, Physiology, Biomechanics, Injury, and Treatment

Ligament injuries are among the most common musculoskeletal injuries seen in clinical practice and ligaments are the most frequently injured structures in a joint. Ligaments play an important role in balancing joint mobility and joint stability. Disruption of joint ligaments severely impairs joint function. Over the past 10 years, a new appreciation of a neuroanatomy and neurophysiology of joint ligaments and its biofeedback loops to surrounding muscles and tendons has emerged to explain the relationship between primary and secondary restraints that allow normal joint motion yet prevent pathological motion. This review focuses on this recent information with a view to new clinical approaches to these common problems.

Clinical outcomes of operative repair of complete rupture of the proximal interphalangeal joint collateral ligament: Comparison with non-operative treatment

Objectives

The purpose of this study was to compare the outcomes of non-operative treatment and operative repair of grade III injuries with complete rupture of the collateral ligament of the proximal interphalangeal (PIP) joint.

Patients and methods

Seventeen patients with grade III injuries with at least 6 months of follow-up were included. Seven patients underwent non-operative treatment and 10 patients underwent operative treatment. We evaluated the following clinical outcomes after treatment: 1) range of motion of the PIP and distal interphalangeal (DIP) joints, 2) joint stability, 3) pain score, and 4) amount of fusiform deformity of the PIP joint.

Results

There was no instability in the lateral stress test in either group. The ranges of motion of the PIP and DIP joints were not statistically different between the two groups at final follow-up. However, the ranges of motion recovered more quickly in the operative group than the non-operative group within the first 3 months after treatment. Patients in the operative group had less pain and better cosmetic appearance of the PIP joint.

Conclusion

Our results suggest that operative repair of the PIP collateral ligament can provide good joint stability, rapid functional recovery, and minimize fusiform deformity of the PIP joint.

Level of evidence

Level III, Therapeutic study.

Injuries of the Proximal Interphalangeal Joint

Proximal interphalangeal joint injuries are common in athletes. In this article the authors discuss the spectrum of injuries of the PIP joint. The clinical and radiological assessment of these injuries will be presented. The principles and options of treatment are outlined. The complications and their possible prevention are discussed.

Ultrasonographic characteristics of volar-lateral ligament constrains after proximal interphalangeal joint injuries

Objective To characterise posttraumatic constrains of the volar-lateral ligaments by analysing volar plate (VP) dynamics after proximal interphalangeal (PIP) joint injuries using ultrasonography. Materials and methods From the anatomical and biomechanical perspectives of the VP and its surrounding structures, posttraumatic constrains of the volar-lateral ligament were evaluated by analysing the changes of VP motion. Using ultrasound, VP motion during active flexion of 0-60° was recorded in the central sagittal plane at 12 weeks after injury. VP trajectories visualised by 5-point tracing on the VP were analysed qualitatively to detect differential patterns of the ligament constrains. Quantitatively, correlation between averaged constrain index determined by measuring volar locational values of the 5 points on the VP and limitation in extension at the final follow-up was assessed. Results Eleven patients with PIP joint injuries involving five VP avulsions, three volar intra-articular fractures, or three dorsal fracture-dislocations were included. All patients with VP avulsion revealed a totally-constrained pattern, whereas patients with intra-articular or fracture-dislocation injuries showed distally-constrained pattern or normal. Averaged constrain index was negatively correlated with limitation in extension, indicating positive contribution of volar-lateral ligament constrains to residual flexion contracture. Conclusion Ultrasonographic visualisation of VP motion characterised posttraumatic constrained conditions of the volar-lateral ligaments. Knowledge of the manner of ligament damages might be useful to set treatment strategies for PIP joint injuries.

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.

In Vivo length changes of the proximal interphalangeal joint proper and accessory collateral ligaments during flexion

PURPOSE

To investigate the length changes in proper collateral ligament (PCL) and accessory collateral ligament (ACL) during flexion of the proximal interphalangeal (PIP) joint in vivo and how portions of the PCL and ACL stabilize the PIP joint.

METHODS

We obtained computed tomography scans of the index, middle, and ring fingers of one hand from 6 volunteers at 0°, 30°, 60°, 90°, and full flexion of the PIP joint. Radial and ulnar PCL and ACL were measured and analyzed with computer modeling.

RESULTS

The data showed that during flexion the average length of the dorsal portion of the radial and ulnar PCL increased significantly and reached a maximum at 90°. The volar portion of the radial and ulnar PCL and the distal portion of the radial and ulnar ACL shortened continuously from extension to full flexion.

CONCLUSIONS

The proximal and middle portions of each ACL are nearly isometric, the dorsal portion of each PCL becomes taut only in flexion, and the volar portion of PCL and the distal portion of ACL become taut only in extension. The current findings indicate that the dorsal portion of PCL is the most stabilizing structure during flexion of the PIP joint, and that the volar portion of PCL and the distal portion of ACL provide the crucial lateral stability to the joint at extension.

CLINICAL RELEVANCE

The results may provide information relevant to the ligaments of PIP joint reconstruction and rehabilitation.

Management of difficult intra-articular fractures or fracture dislocations of the proximal interphalangeal joint

Intra-articular fractures or fracture dislocations of the proximal interphalangeal joint are difficult clinically because the bone and soft tissue structures are small and intricate. Suboptimal treatment of intra-articular fractures typically leads to functional impairment of the hand. This article reviews the current methods of treatment, together with the senior author's experience in treating difficult proximal interphalangeal joint fractures and dislocations. Besides conservative treatments, surgical treatments include open or closed reduction with traditional Osteosynthesis, such as K-wires, screws or plates. Among recent developments are the percutaneous application of thin cannulated compression screws and novel dynamic external fixators. After a preferred minimally invasive treatment with stable reconstruction of the articular surface, sufficient aftercare is necessary to improve surgical outcomes.

Three-dimensional analysis of the palmar plate and collateral ligaments at the proximal interphalangeal joint

The purpose of this study was to analyze the palmar plate complex at the proximal interphalangeal joint using a three-dimensional (3D) technique, which makes it easier to understand the dimensions of structures and their relationship to the adjacent components. This method allows individual elements to be removed virtually, facilitating clearer observation of each component. Sixteen cadaveric specimens were dissected and reconstructed in a 3D virtual environment. The palmar plate is made up of a distal, fibrous portion and a proximal, membranous portion, which anchors distally on the base of the middle phalanx and is continuous with the bilateral check-rein ligaments proximally. The accessory collateral ligaments and the A3 pulley suspend the palmar plate laterally.

Current trends in the management of proximal interphalangeal joint injuries of the hand

Injuries to the proximal interphalangeal joint are commonly encountered by the hand surgeon. Proper diagnosis and treatment are vital for optimal outcomes. Proper treatment of these injuries requires a working knowledge of the anatomy of the joint and an appreciation for principles for reduction, stabilization, and early rehabilitation to provide the best outcomes possible. Injuries can include fractures of the head of the proximal phalanx, dislocations, fracture dislocations, and fractures of the base of the middle phalanx. Similar to other aspects of plastic surgery, there is little high-level evidence guiding treatment and thus most treatment is based on level III or IV evidence. The goal for treatment of any injury around the proximal interphalangeal joint is to establish a congruent joint and allow for early motion. Stiffness and posttraumatic arthritis are common following these injuries. Salvage procedures are limited to arthrodesis and arthroplasty, neither of which can restore the normal function of the hand.

Fracture-dislocations of the proximal interphalangeal joint

Fracture-dislocations of the proximal interphalangeal joint encompass a spectrum of injury severity, ranging from injuries that require little intervention to those that require advanced reconstructive surgery for optimal outcome. Three fracture-dislocation patterns are recognized: dorsal, volar, and pilon. Acceptable outcome is dependent on achieving and maintaining a well-aligned and well-reduced joint, re-establishing normal joint kinematics, and restoring motion. Anatomic articular surface reduction is desirable but not absolutely necessary for a good outcome. Treatment depends on both the type of injury and patient-dependent factors. Optimal outcome for a specific injury is predicated on expedient diagnosis and recognition of injury severity, which enables initiation of appropriate management.

Biomechanical differences of the proximal interphalangeal joint volar plate during active and passive motion: a dynamic ultrasonographic study

PURPOSE

To define the biomechanical differences of the volar plate (VP) of the proximal interphalangeal joint during active and passive motion, which may provide clues to understanding the functional importance of the volar elevation of the VP.

METHODS

We imaged the volar aspect of the proximal interphalangeal joint in 10 healthy middle fingers using ultrasonography. Cine videos recorded the movements of the VP during joint motion from full extension to more than 60° of flexion both actively and passively. We plotted 5 points on the volar surface of the VP and traced them for motion analysis. We statistically analyzed the volar distances and volar angulation of the VP in full extension, 30°, 45°, and 60° of flexion to determine the differences between active and passive flexion.

RESULTS

In active flexion, the VP showed significantly higher volar distances in 45° and 60° and changed its configuration from the original flattened figure to an inverted U shape, with a significant higher angulation at 45° compared with passive flexion. Conversely, in passive flexion, we did not observe the volar elevation of the VP and the flattened configuration was maintained throughout the motion arc.

CONCLUSIONS

From an anatomical viewpoint, volar elevation of the VP seen in active flexion could provide dynamic stresses on the adjacent ligaments and contribute to the stability and smooth gliding of the joint.

Osteoarthritis of the distal interphalangeal joint

Osteoarthritis occurs with the highest prevalence in the distal interphalangeal joint of the hand and has been divided into an erosive and a nonerosive form. The pathogenesis of the early stages of osteoarthritis is poorly understood, but considerable emphasis has been placed on the role of cartilage and subchondral bone as well as soft tissue structures such as collateral ligaments and tendons. Radiographic evaluation represents the most standardized method to quantify disease progression, with different systems having been developed for defining and grading radiographic features. This current concepts article examines the recent knowledge base regarding the etiology, pathogenesis, and evaluation of osteoarthritis of the distal interphalangeal joint.

Distribution of nerve endings in the human proximal interphalangeal joint and surrounding structures

PURPOSE

To examine the distribution of encapsulated nerve endings called mechanoreceptors in the human proximal interphalangeal (PIP) joint and surrounding structures.

METHODS

We processed 12 right index finger PIP joints and surrounding structures from fresh and dissecting-room cadavers for immunohistochemistry of the anti-protein gene product 9.5 and silver staining to detect encapsulated nerve endings. Serial transverse sections were cut throughout the whole specimen and divided into 3 regions along the longitudinal axis: distal, middle, and proximal. Each of the transverse sections was partitioned into dorsal capsule (DC), radial capsule (RC), ulnar capsule (UC), volar plate (VP), radial assemblage nuclei (RAN), and ulnar assemblage nuclei (UAN); the RAN and UAN are located on the radial and ulnar side of the VP. The C1 pulley contained the proximal region of the RAN and UAN, whereas the A3 pulley contained the middle and distal regions. The accessory collateral ligament contained all the regions of the RAN and UAN. The densities of encapsulated nerve endings in these 18 different regions were analyzed and compared.

RESULTS

According to the modified Freeman and Wyke classification, type I (Ruffini-like endings) and type II (Pacini-like endings) nerve endings were identified. The density of type I nerve endings in the proximal region of the VP was substantially higher than that in the proximal region of the RAN, UAN, RC, UC, and DC. The density of type II nerve endings in the proximal region of the RAN and UAN was substantially higher than that in the proximal region of the VP, RC, UC and DC, and that in the proximal region of the VP and DC, respectively.

CONCLUSIONS

Our examination of the distribution of type I and type II nerve endings provides information on the sensory systems of the PIP joints and surrounding structures.

Fractures of the proximal interphalangeal joints of the fingers

Fractures of the proximal interphalangeal joint include a wide spectrum of injuries, from stable avulsion fractures to complex fracture-dislocations. Stability of the joint is paramount in determining the appropriate treatment, which should aim to facilitate early mobilisation and restoration of function.

Proximity of collateral ligament origin to the axis of rotation of the proximal interphalangeal joint of the finger

STUDY DESIGN

Descriptive anatomical study.

OBJECTIVE

To determine the proximity of proximal interphalangeal (PIP) joint collateral ligament origin to the axis of rotation (AOR) of the joint.

BACKGROUND

Normal function of the PIP joints of the hands requires competent collateral ligaments. Studies of the collateral ligaments of the PIP joint have led to a hypothesis that the collateral ligaments of the PIP joints originate at the joint AOR. However, no studies have yet provided quantitative evidence to support this assertion.

METHODS AND MEASURES

A total of 30 collateral ligament specimens were prepared from the radial and ulnar halves of 16 fingers (digits 2 through 5) from the right hands of 5 formalin-embalmed cadavers. A geometric method was employed to estimate the PIP joint AOR. The proximity of collateral ligament origins to the estimated AOR of the PIP joint was determined.

RESULTS

Collateral ligaments were found to have their proximal attachment an average of 0.02 mm distal and 0.24 mm palmar to the PIP joint AOR. For 90% of specimens the center of the collateral ligament origin was within 1.00 mm of the joint AOR.

CONCLUSIONS

These results support the hypothesis that PIP joint collateral ligaments originate at the joint AOR. This finding predicts that the linear distance between the attachments should remain constant as the PIP joint moves through its range of motion. The modest changes in PIP collateral ligament length described in other studies can be attributed primarily to travel of the ligament across a small condylar tubercle at approximately 15 degrees to 20degrees of PIP joint flexion. The practice of immobilizing the PIP joint in 15degreesto 20" egreesof flexion is supported by these findings. J O rthop

Anatomy of the collateral ligaments of the proximal interphalangeal joint

PURPOSE

To study and clarify the anatomy of the proper collateral ligaments and accessory collateral ligaments of the proximal interphalangeal joint.

METHODS

The collateral ligaments of 8 proximal interphalangeal joints were dissected under an operating microscope to gain an appreciation of their fiber direction and the anatomy of their origin and insertion. Two undissected joints were studied histologically.

RESULTS

The proper collateral ligament was found to arise widely from dorsal and proximal to and from the fovea on the side of the head of the proximal phalanx and insert for some distance on most of the side of the base of the middle phalanx. The ligament is stout and its fibers are oriented parallel to the middle phalanx in all positions of the joint. The accessory collateral ligament was found to be a less substantial structure lying between the proper collateral ligament and the volar plate.

CONCLUSIONS

The anatomy shown by this study is quite different from that shown in most of the anatomic and hand surgery literature, particularly in line drawings.

High-resolution magnetic resonance imaging for the assessment of hand osteoarthritis

OBJECTIVE

To investigate the use of a novel surface coil for clinically utilized magnetic resonance imaging (MRI) scanners, in order to describe the microanatomic basis for hand osteoarthritis (OA) at all stages of disease.

METHODS

MRI of proximal or distal interphalangeal joints was performed in 58 subjects: 16 patients with early OA (symptom duration < or =12 months), 14 patients with chronic OA, 10 patients with clinically normal asymptomatic joints adjacent to arthritic joints, and 18 normal controls. High-resolution images were obtained with displayed pixel dimensions of 80-100 mum using a 1.5T scanner and a 23-mm-diameter surface coil. All joint structures were evaluated.

RESULTS

The high-resolution images of every joint structure showed comparable abnormalities in both early and chronic OA, including cartilage loss, bone edema, synovial enhancement, osteophytosis, and erosions. Heberden's and Bouchard's node formation occurred at regions where soft tissue bulged through the capsule between the dorsal tendons and collateral ligaments (CLs). Prominent CL thickening or disruption (100% of OA patients) was evident even in joints where cartilage was partially preserved. Clinically normal joints adjacent to OA hand joints showed thickening and enhancement of CLs which was the most common abnormality seen (80% of OA patients). Older normal subjects showed subtle changes within the CLs.

CONCLUSION

Obtaining high-resolution MR images from clinically utilized scanners represents a novel way for exploring the microanatomic basis of hand arthritis and may have considerable potential in the clinical setting. In the present evaluation in nodal OA, previously unappreciated CL abnormalities were especially common.

Principles of metacarpal and phalangeal fracture management: a review of rehabilitation concepts

Patients with common hand fractures are likely to present in a wide variety of outpatient orthopedic practices. Successful rehabilitation of hand fractures addresses the need to (1) maintain fracture stability for bone healing, (2) introduce soft tissue mobilization for soft tissue integrity, and (3) remodel any restrictive scar from injury or surgery. It is important to recognize the intimate relationship of these 3 tissues (bone, soft tissue, and scar) when treating hand fractures. Fracture terminology precisely defines fracture type, location, and management strategy for hand fractures. These terms are reviewed, with emphasis on their operational definitions, as they relate to the course of therapy. The progression of motion protocols is dependent on the type of fracture healing, either primary or secondary, which in turn is determined by the method of fracture fixation. Current closed- and open-fixation methods for metacarpal and phalangeal fractures are addressed for each fracture location. The potential soft tissue problems that are often associated with each type of fracture are explained, with preventative methods of splinting and treatment. A comprehensive literature review is provided to compare evidence for practice in managing the variety of fracture patterns associated with metacarpal and phalangeal fractures, following closed- and open-fixation techniques. Emphasis is placed on initial hand positioning to protect the fracture reduction, exercise to maintain or regain joint range of motion, and specific tendon-gliding exercises to prevent restrictive adhesions, all of which are necessary to assure return of function post fracture.

The biomechanical properties of the finger metacarpophalangeal joints to varus and valgus stress

PURPOSE

The purpose of this study was to determine the normal biomechanical properties of the passive capsuloligamentous structures about the finger metacarpophalangeal (MCP) joints subjected to dynamic varus/valgus loading and to equate these findings to the clinical situation.

METHODS

The finger MCP joints from 9 fresh-frozen cadaver hands were tested in a custom-designed testing apparatus that applied a varus/valgus force in each direction. Testing was performed at 0 degrees, 30 degrees, 60 degrees, and 90 degrees of MCP joint flexion. Load-displacement curves were generated for each specimen. A nonlinear hysteresis curve was apparent on loading and unloading. A region of collateral ligament laxity was identified whereby minimal torque (< 0.5 Nm) caused progressive joint angulation. Subsequently incremental load was required to produce further joint angulation. The slope of this region was used to calculate early and late collateral ligament stiffness.

RESULTS

The index and long fingers showed a significant decrease in the region of collateral ligament laxity between 0 degrees and 90 degrees. The long finger collateral ligament laxity also diminished significantly between 30 degrees and 90 degrees. The collateral ligament laxity did not significantly change in the ring and small digits throughout MCP joint flexion. The early or late phase of collateral ligament stiffness was not affected by the amount of MCP joint flexion across any of the digits, except in late radial collateral ligament stiffness of the long finger between 0 degrees and 60 degrees.

CONCLUSIONS

The additional stability and clinical observation of tightening of the MCP in flexion appears related to the decreased laxity of the collateral ligaments and not to alterations in the biomechanical properties of the collateral ligaments.

Management of proximal interphalangeal joint fractures and dislocations

Proximal interphalangeal joint (PIP) injuries are among the most common in the hand and their severity is often underestimated. These injuries often lead to prolonged disability, pain, and stiffness. Appropriate treatment includes a thorough assessment, physical examination, and directed imaging. Such an approach should lead to a rational treatment plan that focuses on the rehabilitation of all damaged components, including osseous, articular, and soft tissue structures. This article reviews all elements in the management of PIP injuries and introduces an assessment method for PIP injuries based on the mechanism of injury rather than primarily on the basis of radiographic findings.

Operative repair of a chronic, ulnar proximal interphalangeal dislocation of the little finger with an excellent functional result

Chronic dislocations of the proximal interphalangeal joint are not common. The instability and physical impairment, however, can render the digit or hand quite dysfunctional. A case report of the reconstruction of a nine-year chronic proximal interphalangeal joint dislocation of the left little finger is presented. The functional recovery is described. A literature review of the treatment of chronic dislocations of the proximal interphalangeal joint is also discussed.

Fractures of the proximal interphalangeal joint

Fractures of the proximal interphalangeal joint constitute a broad spectrum of injuries. An understanding of the anatomy, the potential for joint instability, and the treatment options is essential to management of these fractures. Commonly observed fracture patterns involve one or both condyles of the proximal phalanx or the base of the middle phalanx. Fractures of the middle phalanx may involve the palmar lip or the dorsal lip or may be a "pilon" type of injury involving both the palmar and the dorsal lip with extensive intra-articular comminution. Intra-articular injuries may lead to joint subluxation or dislocation and must be identified in a timely manner to limit loss of motion, degenerative changes, and impaired function. These injuries range from those requiring minimal intervention to obtain an excellent outcome to those that are challenging to the most experienced surgeon. The treatment options include extension-block splinting, percutaneous pinning, traction, external fixation, open reduction and internal fixation, and volar-plate arthroplasty. Prompt recognition of the complexity of the injury and appropriate management are essential for an optimal functional outcome.

Implant arthroplasty of the hand: retrospective and prospective considerations

Small joint arthroplasty has lagged behind the development of that in large joints because of their small sizes, different shapes, presence within kinetic chains, complex soft tissue investments, presence of adjacent rays, secondary displacement and contracture, and the differing requirements of degenerative and rheumatoid arthritis. Prosthetic development must take into consideration range of motion, stability, tendon moment arms, fixation, ease of implantation, biocompatibility, wear and strength characteristics, and soft tissue reconstruction. The metacarpophalangeal, interphalangeal, and trapeziometacarpal joints each present different problems in the design of kinematic equivalent prostheses. One-piece polymeric designs have advantages in cost, adaptability, and known performance but show degradation of function with time. Total joint designs have the potential of better simulating normal joint function but have shown tendencies to subsidence, loosening, and breakage. The rigidity of hinge joints limits the damping of out-of-plane forces and places greater stress on bone-stem interfaces, whereas global designs have poor constraint features.

Surgical repair of acute collateral ligament injuries in digits with the Mitek bone suture anchor

Eighteen acute grade III collateral ligament injuries were treated by using the Mitek bone suture anchor. Seven were thumb metacarpophalangeal joint injuries, and eleven were finger proximal interphalangeal joint injuries. Seventeen patients were followed more than 12 months after surgery. All patients were able to use the digits in daily living activities within 5 weeks after surgery, and return to their original work or sports activities within 12 weeks. Pain was completely relieved in 15 patients. Loss of joint motion averaged 7 degrees. In all joints the postoperative lateral stress angle was within 10 degrees of that of the contralateral digit.

Development of a surface replacement arthroplasty for proximal interphalangeal joints

Sixty-six surface replacement proximal interphalangeal prostheses with a CrCo proximal and an ultrahigh-molecular-weight polyethylene distal component were used in the hands of 47 patients (mean age, 58 years) over a 14-year period. There were 37 fingers with degenerative arthrosis, 16 with traumatic arthrosis, and 13 with rheumatoid arthritis. The mean follow-up period was 4.5 years (range, 1-14 years). The results based on pain relief, motion, and deformity were good in 32 fingers, fair in 19, and poor in 15. Poor results occurred primarily in fingers with previous extensive injury or static deformity. Results with a dorsal approach were better than those with a lateral or palmar approach. Component loosening at the bone-cement junction beyond a minimal radiolucent line was seen in one late x-ray. Results in individuals changed little after the first year of follow-up care, but results overall improved during the course of the study, perhaps because of improvements in surgical technique and experience.

Biomechanics of the intact and surgically repaired proximal interphalangeal joint collateral ligaments

Collateral ligament injuries to the proximal interphalangeal joint are common. When the collateral ligament is completely ruptured, surgical repair may be required. The strength of the lateral collateral ligaments of the proximal interphalangeal joint was examined using axial distraction on an electrohydraulic testing apparatus. Eighty-five fresh human adult cadaver fingers were assessed; 38 intact ligaments were first examined. The strength of the native ligament was 162.5 N. Forty-seven ligament repair preparations were tested: suture repair (27.8 N), pull-out wire repair (35.9 N), and repair using a Mitek suture anchor (38.4 N). The breaking strength of the intact ligaments was significantly greater than that of any repair. All repaired ligaments failed at the site of the repair. The ligaments repaired by the pull-out wire and Mitek anchor technique were significantly stronger than those repaired with the suture technique.

Lateral stability of proximal interphalangeal joint replacement

The lateral stability of the cadaver proximal interphalangeal joint was studied with an electromagnetic tracking system before and after implant replacement. Ten middle fingers were retrieved and randomly divided into two groups for joint replacement with either a silicone rubber flexible finger joint implant or a custom surface replacement prosthesis. Each finger was mounted on a fixture that allowed loading of the proximal interphalangeal joint with tension through the flexor, extensor, and intrinsic tendons. For the intact proximal interphalangeal joint under lateral stress, lateral angulation averaged 4 degrees in extension and 8 degrees with the joint in 60 degrees of flexion. Although lateral angulation increased after surface replacement prosthesis implantation when the joint was flexed more than 20 degrees, comparison with the intact joint showed no statistical difference. With the silicone implant, lateral angulation became more pronounced even in the extended position and showed a significant difference when the proximal interphalangeal joint was flexed more than 20 degrees.

Distal unicondylar fractures of the proximal phalanx

The records of 38 consecutive patients (38 fractures) who underwent treatment for distal unicondylar fractures of the proximal phalanx were reviewed to evaluate fracture characteristics, mechanism of injury, treatment options, and functional outcomes. Four classes of fracture pattern were defined radiographically. Most fractures occurred during ball sports and involved an axial splitting of extended digits, with the condyle closet to the midline of the hand fracturing most commonly. We believed that the fracture occurred as a result of tension loading due to a distraction force from the collateral ligament. All fractures healed. Follow-up examination averaged 3 years. Five of seven nondisplaced fractures treated with splinting and four of ten displaced fractures treated with reduction and single Kirschner wire fixation displaced. Fractures treated with multiple Kirschner wire fixation had the best final joint motion. Class IV fractures with a small palmar coronal fragment had the poorest final motion. A short period of post-operative immobilization did not adversely affect final proximal interphalangeal joint motion. We recommend multiple Kirschner wire or miniscrew fixation of these fractures as the most predictable method of treatment. Final proximal interphalangeal joint motion is not uniformly excellent in patients with these fractures.

Stability and constraint of the proximal interphalangeal joint

The kinematics of the intact proximal interphalangeal joint of 12 fresh cadaver index fingers were measured by means of an electromagnetic tracking system. The specimens were then randomly divided into two groups for ligament sectioning in two different sequences and for testing under lateral stress. Lateral stress of the intact proximal interphalangeal joints produced an average of 5 degrees of adduction and 9 degrees of supination motion throughout the arc of flexion/extension. Maximum lateral angulation was 15 degrees under 1 kg of force (30 N cm) applied at the distal end of the middle phalanx. Joint angulation increased to 20 degrees after total sectioning of the collateral ligament. Joint laxity was greatly reduced in full extension, in full flexion, and when the muscles were loaded. The proximal interphalangeal joint remained stable when one half of the collateral ligament was left intact. The results indicate that lateral stability of the proximal interphalangeal joint is provided primarily by the collateral ligament. When the lateral stress test is normal in proximal interphalangeal joint extension, an additional test in 20 to 30 degrees of flexion should be considered to avoid a false-negative result. Angulation greater than 20 degrees is abnormal and indicates a loss of collateral ligament integrity.

A biomechanical study of the collateral ligaments of the proximal interphalangeal joint

Collateral ligament injuries of the proximal interphalangeal joint are common. A significant number of these injuries result in complete rupture of the ligament. The forces that damage the ligaments are abduction and adduction stresses. Previous studies have investigated laxity, angulation, and patterns of failure, but detailed biomechanical rupture studies are scant. Sixty-eight proximal interphalangeal joints from fresh human cadaver fingers (average age, 67 years) were stressed at velocities of 1 mm/sec, 4 mm/sec, and 10 mm/sec. Sectioning studies were also done. Four distinct rupture patterns were noted: midsubstance tear, proximal detachment, distal detachment, and distal avulsion fracture. The prevalence of these patterns differed with the rate at which the ligaments were stressed. Lower speeds tended to produce midsubstance tears, while higher speeds yielded distal damage. The study confirmed that the lateral collateral ligament is the primary restraint against medial-lateral stress and that other supporting structures (the extensor hood and the palmar plate) did not contribute significantly to side-to-side stability.

Contracture of the proximal interphalangeal joint in Dupuytren's disease

The correction of fixed flexion deformity at the P.I.P. joint in Dupuytren's disease is often difficult. This paper reports an anatomical study of this joint in fingers amputated because of this condition. all the joints would extend fully after release of the accessory collateral ligaments and volar plate. Lateral and dorsal structures showed severe secondary damage and it is suggested that these changes may explain the poor results of corrective surgery to this joint in Dupuytren's disease.