Stability and constraint of the proximal interphalangeal joint

The retinacular ligaments of the digital extensor expansion revisited: An anatomical and biomechanical study

Our aim was to clarify the anatomy and function of the retinacular ligaments. Forty-eight fingers were dissected and the thickness of the oblique retinacular ligament (ORL) was graded. In four fingers, the motion in the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints was subjected to an in-depth analysis before and after sectioning of either the lateral bands (LB) or the ORLs. The function of the ORLs in restricting flexion of the DIP joint with full extension of the PIP joint was measured in 10 fingers. An ORL could be identified on both sides in all 48 fingers. The distribution of the insertion on the proximal phalanx was 7/96 (7%) in the distal third, 70/96 (73%) in the middle third and 19/96 (20%) in the proximal third. Among the specimens, 29% were graded as having a strong bundle of fibers, 51% as having well-defined and regular fibers and 20% as having thin and sparse fibers. With the PIP joint extended, there was a statistically significant increase in flexion of the DIP joint after the ORL was cut. After the LB was sectioned, the ORL was able to extend the DIP joint with an extension lag of 10-22°. Cutting the ORL did not affect the ability to extend that joint. We conclude that the retinacular ligaments are consistent. Their major role is not connected with finger movement, but to provide stabilizing links between the PIP and DIP joints. They are active in not only specific, uncommon finger positions but also in ordinary use of the fingers.

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.

Shifting the paradigm: ankylosis arthroplasty for the proximal interphalangeal joint with a novel collateral ligament reconstruction

Silicone arthroplasty for proximal interphalangeal joint ankylosis is rarely performed, partly due to the potential for lateral joint instability. We present our experience performing proximal interphalangeal joint arthroplasty for joint ankylosis, using a novel reinforcement/reconstruction technique for the proper collateral ligament. Cases were prospectively followed-up (median 13.5 months, range 9-24) and collected data included range of motion, intraoperative collateral ligament status and postoperative clinical joint stability; a seven-item Likert scale (1-5) patient-reported outcomes questionnaire was also completed. Twenty-one ankylosed proximal interphalangeal joints were treated with silicone arthroplasty, and 42 collateral ligament reinforcements undertaken in 12 patients. There was improvement in range of motion from 0° in all joints to a mean of 73° (SD 12.3); lateral joint stability was achieved in 40 out of 42 of collateral ligaments. High median patient satisfaction scores (5/5) suggest that silicone arthroplasty with collateral ligament reinforcement/reconstruction should be considered as a treatment option in selected patients with proximal interphalangeal joint ankylosis.Level of evidence: IV.

Midterm clinical outcomes of collateral ligament repair of the thumb and lesser digits: a retrospective analysis of 35 cases

Background

Finger collateral ligament injuries are common, and conservative treatment usually works well. However, complete ruptures that lead to instability could cause painful disability. This study presents our clinical experience and a qualitative functional evaluation following the surgical repair of the thumb and proximal interphalangeal (PIP) joint collateral ligament ruptures.

Methods

Thirty-five patients (22 men and 13 women), diagnosed via a physical examination and magnetic resonance imaging (MRI) with a total collateral ligament rupture in the metacarpophalangeal thumb (16) and PIP joints of the lesser digits (19) and treated surgically, were evaluated retrospectively. The limited range of motion; functional score by Saetta; disabilities of the arm, shoulder, and hand (DASH) score; pre- and post-operative pain, deformity level; and post-operative ability to grip keys, buttons, and jars were measured. The significance of the change between the pre and post-operative visual analog scale for pain (VAS) scores were evaluated using the Wilcoxon signed-rank test. The difference between the lesser digits and thumb groups by patient age was evaluated using the Mann–Whitney-U test. All data, such as the mean, range, and standard deviation, were calculated using SPSS.

Results

The mean pre- and post-operative VAS scores were 4.8 (from 3 to 7) and 0.91 (0 to 4), respectively. The mean post-operative limitation in the range of motion was 9.78° (s = 14.47) for lesser digits and 6.87° (s = 12.29) for the thumb. According to Seatta et al., the final functional score was 62.5% excellent, 25% good, and 12.5% moderate for the thumb and 84.2% excellent, 10.5% good, and 5.3% poor for the lesser digits. The mean post-operative DASH score was 13.55 (SD: 8.77) for lesser digits and 14.22 (SD: 8.9) for the thumb. The mean contralateral (healthy) hand DASH score was 0.75 (SD: 1.05) for lesser digits and 0.75 (SD: 1.05) for the thumb. For the thumb and lesser digits, the z-scores were − 3.55 and − 3.787, respectively, and the progress of the VAS score was significant (p < 0.05).

Conclusion

After a 40-month follow-up for 35 acute, subacute, and chronic cases, the results suggest that direct and suture-anchor repairs are feasible, painless treatments associated with good finger function.

The Accuracy and Cost-Effectiveness of MRI Assessment of Collateral Ligament Injuries of the Lesser Digits’ Proximal Interphalangeal Joints

Background

Collateral ligament injuries of the thumb and lesser digits are simple injuries, but they may lead to disabilities in hand function. This study aimed to evaluate the accuracy and cost-effectiveness of magnetic resonance imaging (MRI) in diagnosing proximal interphalangeal (PIP) collateral ligament injuries of lesser digits.

Methods

A retrospective evaluation was conducted on 18 fingers that had undergone surgery for PIP joint complete collateral ligament injury. Pre-operative MRI results were compared with the intra-operative findings. The data from MRI and direct intraoperative findings were analyzed by the Chi-square test in paired groups. The McNemar test analyzed the accuracy of the MRI test for detecting volar plate injuries. Statistical Packages for Social Sciences (SPSS) version 25 (IBM Inc., Armonk, New York) software program was used for the analysis. 

Results

In digits other than the thumb, the accuracy of MRI for detecting collateral injuries was 38.89%, and detection was incorrect in 11 (61.11%) of 18 patients. There are significant differences between MRI and Intraoperative results (p<0.001). MRI findings for seven fingers (38.89%) of the 18 fingers involved were compatible with the surgery results (38.88%). By comparison, the MRI findings of 11 fingers (61.11%) were inconsistent with the intra-operative results. Eight patients (44.44%) were diagnosed preoperatively with MRI as having volar plate ruptures, three patients (16.67%) were diagnosed with open surgery, but only three of the volar plate diagnosed patients with MRI were verified as ruptures during open surgery (38.0%). In addition, preoperatively undetected volar plate injuries by MRI (n=10) were detected intra-operatively in three cases (30.0%). Therefore, the accuracy of MRI was found not to be statistically significant for the detection of volar plate injuries (p=0.727).

Conclusion

This study concluded that a 1.5-Tesla MRI with a slice thickness of 2-3 mm should not be relied on as a decisive tool for diagnosing collateral ligament injuries of the PIP joint of the lesser digits. Additionally, MRI was found insufficient for diagnosing volar plate injuries that accompanied collateral ligament injuries. Given these findings, one might conclude that MRI is not cost-effective in diagnosing collateral ligament injuries of the lesser digits PIP joint.

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.

The management of acute fracture dislocations of proximal interphalangeal joints: a systematic review

LEVEL OF EVIDENCE

III.

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.

Management of Proximal Interphalangeal Joint Fracture Dislocations

Fracture dislocations of the proximal interphalangeal (PIP) joint of the finger are often caused by axial load applied to a flexed joint. The most common injury pattern is a dorsal fracture dislocation with a volar lip fracture of the middle phalanx. Damage to the soft-tissue stabilizers of the PIP joint contributes to the deformity seen with these fracture patterns. Unfortunately, these injuries are commonly written off and left untreated. A late-presenting PIP joint fracture dislocation has a poor chance of regaining normal range of motion. The provider must be suspicious of these injuries. Treatment options and algorithm are reviewed.

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.

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.

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.

Proximal interphalangeal joint dislocations and treatment: an evolutionary process

Background

Proximal interphalangeal joint (PIPJ) dislocations represent a significant proportion of hand clinic visits and typically require frequent follow-ups for clinical assessment, orthotic adjustments, and physiotherapy. There are a large number of treatment options available for PIPJ dislocations, yet no prospective or controlled studies have been carried out, largely due to the diversity of the various types of injuries.

Methods

We retrospectively reviewed all the PIPJ dislocations in our institution over a five-year period and directly compared the different splinting techniques that we have used over this time frame.

Results

There were a total of 77 dislocations of the PIPJ (57 men and 20 women) that were included in our study. We found that our management has shifted gradually from complete immobilisation to controlled early mobilisation with figure-of-eight splints. Following treatment, the range of motion of the PIPJ in the figure-of-eight group was significantly greater than that in the other three methods (P<0.05) used. There were significantly fewer hospital visits in the figure-of-eight splint group than in the other treatment groups.

Conclusions

The treatment of PIPJ dislocations has undergone a significant evolution in our experience. Early controlled mobilisation has become increasingly important, and therefore, splints have had to be adapted to allow for this. The figure-of-eight splint has yielded excellent results in our experience. It should be considered for all PIPJ dislocations, but careful patient selection is required to achieve optimum results.

Osteoarticular pedicle flap from the capitate to reconstruct traumatic defects in the head of the proximal phalanx

PURPOSE

To describe the reconstruction of traumatic defects in the head of the proximal phalanx using an osteoarticular pedicle flap from the capitate.

METHODS

From January 2004 to December 2007, we treated 15 patients with traumatic defects of the head of the proximal phalanx at our institution. All of these injuries involved 1 condyle of the proximal phalanx. There were 11 male and 4 female patients; the mean age was 32 years. The injuries occurred in the index (n = 6), middle (n = 7), and ring (n = 2) fingers. At the final follow-up, we assessed space narrowing of the proximal interphalangeal joint and flap necrosis using plain radiography. We measured active motion and pinch and grip strength of the hand and compared all measurements with those on the opposite side. Patients rated injured-joint pain and donor-joint pain using a visual analog scale. We assessed hand function using the Disabilities of the Arm, Shoulder, and Hand scale.

RESULTS

Patient follow-up averaged 52 months. At the final follow-up, we noted narrowing of the proximal interphalangeal joint in 3 cases, but we observed no flap necrosis. The mean active motion arc of the injured and opposite proximal interphalangeal joints was 50° and 96°, respectively. The mean pinch strength of the injured and opposite hands was 5.8 and 6.5 kg, respectively. The mean grip strength of the injured and opposite hands was 39 and 40 kg, respectively. We noted mild recipient joint pain in 6 patients and mild donor joint pain in 1 patient. The mean score of the Disabilities of the Arm, Shoulder, and Hand questionnaire was 9.

CONCLUSIONS

We used an osteoarticular pedicle flap from the capitate to resurface traumatic defects of the head of the proximal phalanx. This approach is acceptable for restoring the contour of the phalangeal head.

Proximal interphalangeal joint fracture dislocations: stable and unstable

Injuries to a competitive athlete's hand are common occurrences routinely treated by team training staff and physicians. These injuries are particularly prevalent in contact and ball catching sports. Although timely recognition and treatment of these injuries can avoid lifelong morbidity, the initial presentation may be deceptively benign. These injuries are classified according to the pattern of fracture and the resultant stability of the joint. Treating physicians must have an understanding of the biomechanics, injury patterns, assessment, and treatment guidelines in order to identify these injuries and provide for the earliest safe return to play with the best functional outcome for the athletes.

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.

Long-term outcomes of proximal interphalangeal joint surface replacement arthroplasty

BACKGROUND

Surface replacement arthroplasty is a reconstructive alternative for the treatment of pain and deformity due to osteoarthritis and rheumatoid arthritis of the proximal interphalangeal joint of the finger. This retrospective study was performed to examine long-term outcomes of proximal interphalangeal joint prosthetic surface replacement with a proximal cobalt-chromium (CoCr) and distal ultra-high molecular-weight polyethylene component over thirty years at a single institution.

METHODS

Sixty-seven prostheses were implanted in forty-seven patients between 1974 and 2007. The mean duration of follow-up was 8.8 years. There were fifty joints (75%) with osteoarthritis and seventeen (25%) with rheumatoid arthritis. Fifty-six prostheses (84%) were implanted via a dorsal approach, forty-eight (72%) were cemented, and nineteen (28%) were press-fit. Postoperative evaluation, consisting of a clinical history and examination, radiographs, the Short Form-36 (SF-36) and Disabilities of the Arm, Shoulder and Hand (DASH) questionnaires, and a visual analog scale (VAS) pain score, was performed for thirty-six patients. Demographic, surgical, and implant failure data were obtained from the medical charts of eleven patients (sixteen implants) who had died prior to the time of postoperative follow-up.

RESULTS

At the time of follow-up, the median total active proximal interphalangeal joint motion was 40°. Eight prostheses had failed, yielding a cumulative incidence of implant failure of 3% at one year, 8% at three years, 11% at five years, and 16% at fifteen through twenty-five years. Prostheses implanted via a volar approach failed more often than those implanted via a dorsal approach (relative risk: 6.59, p = 0.004). The failure rate did not differ significantly between patients with rheumatoid arthritis and those with osteoarthritis (p = 0.17). The median VAS pain score at the time of follow-up was 3 (of a maximum of 100). There were twenty-two complications in fourteen patients, resulting in four interphalangeal fusions and two amputations. There were no infections.

CONCLUSIONS

Proximal interphalangeal surface replacement arthroplasty is a reliable treatment alternative for pain and deformity due to proximal interphalangeal joint osteoarthritis and rheumatoid arthritis. At the time of long-term follow-up, pain was minimal and joint motion was similar to preoperative levels.

Surface replacement arthroplasty of the proximal interphalangeal and metacarpophalangeal joints: The current state

Surface replacement arthroplasty for proximal interphalangeal joint and metacarpophalangeal joints are becoming popular. Low profile, anatomically designed implants limit the amount of bone removed but need preservation of the collateral ligaments. Pyrocarbon and cobalt-chrome stemmed unconstrained implants on ultra-high molecular weight polyethylene are the two commonly available bearing surfaces. The indications for small joint arthroplasty are degenerative, post-traumatic or rheumatoid arthritis. Early results are encouraging, primarily in patient satisfaction and pain relief, but are based on low numbers. The main concerns are progressive loss of range due to implant settling, dislocation, squeaking and poor osteo-integration with the appearance of a radiolucent line at the bone-implant interface. Our experience suggests that metacarpophalangeal joint replacements consistently give good results.

Hemi-hamate arthroplasty for pilon fractures of finger

BACKGROUND

Injury following proximal interphalangeal joint fracture dislocation is determined by the direction of force transmission and the position of the joint at the time of impact. Dorsal dislocations with palmar lip fractures are the most frequently encountered. The degree of stability is directly determined by the amount of middle phalangeal palmar lip involvement.

MATERIALS AND METHODS

Hemihamate arthroplasty procedure was used in the reconstruction in five cases with comminuted, impacted fractures of the proximal end of middle phalanx of the finger. Three patients were presented within 2 weeks; one patient came by one month and the other by three months following the injury. All patients presented with posterior subluxation of PIP joint.

RESULTS

Functional outcome following this procedure in both acute and chronic cases resulted in adequate restoration of joint stability and function.

CONCLUSIONS

Hemihamate arthroplasty is an adjuvant in the treatment of unstable intra-articular pilon fracture involving PIP joint.

Kinematic performance of a six degree-of-freedom hand model (6DHand) for use in occupational biomechanics

Upper extremity musculoskeletal disorders represent an important health issue across all industry sectors; as such, the need exists to develop models of the hand that provide comprehensive biomechanics during occupational tasks. Previous optical motion capture studies used a single marker on the dorsal aspect of finger joints, allowing calculation of one and two degree-of-freedom (DOF) joint angles; additional algorithms were needed to define joint centers and the palmar surface of fingers. We developed a 6DOF model (6DHand) to obtain unconstrained kinematics of finger segments, modeled as frusta of right circular cones that approximate the palmar surface. To evaluate kinematic performance, twenty subjects gripped a cylindrical handle as a surrogate for a powered hand tool. We hypothesized that accessory motions (metacarpophalangeal pronation/supination; proximal and distal interphalangeal radial/ulnar deviation and pronation/supination; all joint translations) would be small (less than 5° rotations, less than 2mm translations) if segment anatomical reference frames were aligned correctly, and skin movement artifacts were negligible. For the gripping task, 93 of 112 accessory motions were small by our definition, suggesting this 6DOF approach appropriately models joints of the fingers. Metacarpophalangeal supination was larger than expected (approximately 10°), and may be adjusted through local reference frame optimization procedures previously developed for knee kinematics in gait analysis. Proximal translations at the metacarpophalangeal joints (approximately 10mm) were explained by skin movement across the metacarpals, but would not corrupt inverse dynamics calculated for the phalanges. We assessed performance in this study; a more rigorous validation would likely require medical imaging.

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.

[Intraarticular fractures of the proximal interphalangeal joint: dynamic early functional therapy with an external fixation system]

The results of treating fracture dislocations of the proximal interphalangeal joint are often unsatisfactory for the patient because conservative methods cannot prevent stiffness of the joint. Thus, early functional treatment with external fixation systems is increasingly favoured. This therapy combines the principles of ligamentotaxis and the possibility of early movement of the injured joint. The frequently modified pins and rubbers traction system is especially effective. It is cheap, easy to apply, and well accepted by patients due to its light weight and small size. This paper gives an overview of the therapeutic options and the clinical results of treating fractures of the proximal interphalangeal joint.

Management of proximal interphalangeal joint dislocations in athletes

Proximal interphalangeal joint dislocations are common athletic injuries. In dislocations and fracture dislocations, the most important treatment principle is congruent joint reduction and maintenance of stability. This article reviews the relevant anatomy, injury characteristics, and treatment options for proximal interphalangeal joint dislocations and fracture dislocations. Treatment methods discussed include closed reduction, percutaneous fixation, and open reduction.

The volar approach to proximal interphalangeal joint arthroplasty

Proximal interphalangeal joint arthroplasty has resulted in good outcomes in patients treated for osteoarthritis, posttraumatic arthritis, and rheumatoid arthritis. Most hand surgeons complete arthroplasties of the proximal interphalangeal joint through a dorsal approach. However, for the past 7 years, we have had positive results with a volar approach. We describe this technique, which avoids injury to the extensor tendon and allows for a more simplified approach to postoperative therapy compared with the therapy regimen required after the dorsal approach.

Surface replacement arthroplasty of the proximal interphalangeal joint

The first proximal interphalangeal joint (PIPJ) replacements were hinged devices with single-axis motion. Newer implant arthroplasties of the PIPJ have anatomically designed proximal phalangeal and middle phalangeal components. A need to create balanced forces across the joint was the rationale for the semiconstrained PIPJ prosthesis, which uses an anatomic design. These low-profile implants limit bone excision while preserving the integrity of the collateral ligaments. Paramount in the success of this implant is maintaining the integrity of the insertion of the central slip as it inserts on the base of the middle phalanx. The proximal and middle phalanx should be broached such that the largest implant can be press-fit in place. Greater stability is gained with a collateral ligament-preserving implant. Patient selection should include those patients with sufficient soft-tissue integrity. In general, patients with inflammatory disorders, collateral ligament insufficiency, and acute or chronic PIPJ septic arthritis are poor candidates for PIPJ surface replacement arthroplasty.

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

Pyrolytic carbon arthroplasty for posttraumatic arthritis of the proximal interphalangeal joint

PURPOSE

To prospectively evaluate the subjective and objective functional outcome of patients treated with a pyrolytic carbon proximal interphalangeal (PIP) joint arthroplasty for posttraumatic arthritis.

METHODS

Five patients (7 joints) with traumatic injuries to the PIP joint were followed up for more than 1 year after pyrolytic carbon arthroplasty. All patients were treated with surgical reduction and stabilization at the time of the initial injury, but at a minimum of 6 months after the initial injury they had persistent pain, loss of motion, and functional limitations. All patients had a stable PIP joint with a satisfactory extensor mechanism but had radiographic evidence of posttraumatic arthritis. Patients were evaluated before and after arthroplasty with the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire and visual analog scale and by radiographic and physical examination.

RESULTS

At an average of 17 months, the mean DASH questionnaire score was unchanged. The pain rating on the visual analog scale was 6 out of 10 before surgery and 4 out of 10 after surgery; this change was not statistically significant. The average range of motion of the PIP joint decreased by 10 degrees at the last evaluation. Grip strength improved from an average of 47 lb to 63 lb after surgery.

CONCLUSIONS

The subjective and objective functional outcomes in 5 patients more than 1 year after pyrolytic carbon PIP joint arthroplasty for PIP joint trauma were disappointing. For posttraumatic patients, we no longer use pyrolytic carbon PIP joint arthroplasty.

Prosthetic replacement of the proximal interphalangeal joint

The first proximal interphalangeal joint (PIPJ) replacements were hinged devices allow-ing only single-axis motion. Newer implant arthroplasties of the PIPJ have anatomically designed proximal phalangeal and middle phalangeal components. Constrained devices have typically lead to failure at the hinge mechanism or the prosthetic bone interface. A need to create balanced forces across the joint was the rationale behind the semicon-strained PIPJ prosthesis, which uses an anatomic design. Limitations of the silicone PIPJ implant include its lack of resistance to valgus loading at the index and long digits during the pinch maneuver. It is generally believed that a PIPJ surface replacement arthro-plasty that preserves the collateral ligaments will achieve greater PIPJ stability.

Dynamic intradigital external fixation for proximal interphalangeal joint fracture dislocations

PURPOSE

Many skeletal traction devices have been described to treat fracture dislocations of the proximal interphalangeal (PIP) joint. Most of these techniques are technically challenging or involve cumbersome frames. We present a design modification that enhances the stability of a simple dynamic fixation system described previously and report our results with this technique.

METHODS

A previously described simple dynamic fixator with no rubber bands was applied to 6 patients who sustained fracture dislocations of the PIP joint. The middle finger was involved in 3 patients, the ring finger in 1 patient, and the small finger in 2 patients. The average age of the patients was 27 years (range, 21-42 y). The average involvement of the base of the middle phalanx was 48% (range, 35% to 60%). The average time from the injury to the surgery was 6 days (range, 1-14 d). The average follow-up period was 24 months (range, 7-43 mo). Immediate active flexion extension was allowed and the fixator was removed after 3 to 4 weeks.

RESULTS

The average range of motion of the PIP joint at the final follow-up evaluation was 5 degrees to 89 degrees (range, 0 degrees to 100 degrees ). Two patients developed pin track infection that resolved with oral antibiotics. Only one patient complained of mild pain with extreme flexion. Proper reduction and congruency of the joint was noted on final anteroposterior and lateral radiographs.

CONCLUSIONS

A simple dynamic fixator for the treatment of unstable PIP joint fracture dislocations was used successfully in 6 digits to maintain reduction and restore digital range of motion. The addition of modifications to the original technique not only improves the solidity of the construct but also provides satisfactory functional results. Based on our experience we recommend this easy technique to treat fracture dislocations of the PIP joint.

New-generation implant arthroplasties of the finger joints

Prosthetic replacement in the hand must address such unique challenges as preservation of the collateral ligaments, tendon balancing, and stability. Some recently developed implant arthroplasties of the metacarpophalangeal and proximal interphalangeal joints have anatomically designed articular components; others have non-cemented, press-fit, carefully contoured intramedullary stems. The rationale behind developing the unlinked or semiconstrained prosthesis with anatomic geometry is that it would create balanced forces across the joint. Low-profile, anatomically designed implants limit the amount of bone removed and preserve the integrity of the collateral ligaments. A metacarpophalangeal joint implant with an elliptical metacarpal head and a nonfixed center of rotation can enhance stability in flexion through greater articular contact. A proximal interphalangeal joint implant that preserves the collateral ligaments also can achieve improved stability. Component loosening is not an early complication with these recent designs, and arc of motion is satisfactory.

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.

Athletic hand injuries

Hand injuries are among the most common injuries arising from athletic participation. Suboptimal outcomes from poorly treated athletic hand injuries can produce functionally disabling injuries. Careful assessment and, when needed, radiographic studies are critical for the accurate and complete diagnoses of hand injuries. Carefully thought out modifications may accelerate the time for return to competition. A thorough understanding of these many variables can enable the physician to minimize time lost without compromising care.

Ulnar deviation after volar subluxation of the proximal interphalangeal joint

A rare case of irreducible and progressive ulnar deviation after volar subluxation of the proximal interphalangeal joint is presented. An immobilized proximal interphalangeal joint with remaining volar subluxation after improper reduction showed ulnar deviation at 3 weeks after injury. During surgery, the radial collateral ligament was found to be ruptured at its origin, with formation of concomitant scar tissues. There were no apparent lesions at the central slip, lateral band, and volar plate. Interposition of the ruptured ligament and infiltration of the surrounding scar tissues into the proximal interphalangeal joint were identified. Surgical incision of the capsule along the dorsal margin of the radial collateral ligament readily produced successful reduction. The irreducible and progressive ulnar deviation of the proximal interphalangeal joint seemed to result from gradual infiltration of the scar tissues, subsequent to remaining volar subluxation because of interposition of the ruptured collateral ligament.

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.

Kinematics of the proximal interphalangeal joint of the finger after surface replacement

Nine fresh-frozen normal human cadaveric long fingers were used to compare the kinematics of the proximal interphalangeal joint (PIP) before and after a resurfacing metal-polyethylene prosthetic replacement (Avanta prosthesis, San Diego, CA) using the magnetic Isotrak system (Polhemus Navigational Systems, Colchester, VT). The kinematics of the PIP joint after replacement were similar to that of the normal joint. The maximum angular displacement was 5 degrees for lateral deviation and 9 degrees for rotation during the passive flexion and extension motion. The center of rotation after implant insertion was nearly identical to the center of rotation of the normal joint. This anatomically designed PIP prosthesis has potential to restore normal motion to the finger PIP joint while resisting physiologic out-of-plane forces such as pinch and grasp.

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.

Distribution of collagens and glycosaminoglycans in the joint capsule of the proximal interphalangeal joint of the human finger

BACKGROUND

The capsule of the proximal interphalangeal joint consists of the central slip of the extensor tendon dorsally, the collateral ligaments at the sides and the palmar ligament ventrally. Fibrocartilaginous menisci have been reported extending into the joint cavity and the central slip has a sesamoid fibrocartilage articulating with the proximal phalanx. This study relates ECM composition in the joint capsule to function.

METHODS

Each part of the capsule from 24 fingers amputated because of trauma, carcinoma, isthaemia, fixed-flexion deformities or Dupuytren's contracture, was dissected out. Sections were prepared for routine histology or immunolabelled with a panel of monoclonal and polyclonal antibodies against collagens and glycosaminoglycans using the avidin/biotin/peroxidase procedure.

RESULTS

All parts of the capsule consistently labelled for types I, III and VI collagens and for dermatan and keratan sulphate, though labelling was more pericellular in fibrocartilaginous regions. In contrast, only certain regions of the capsule in some fingers labelled for type II collagen, chondroitin 4 or 6 sulphate. The sesamoid fibrocartilage in the central slip showed the greatest degree of fibrocartilage differentiation, especially in fixed-flexion deformity fingers, and the palmar ligament the least.

CONCLUSIONS

The immunolabelling patterns suggest that there is an ordered sequence of matrix changes accompanying fibrocartilage differentiation. Chondroitin sulphate-containing proteoglycans accumulate first, and type II collagen appears later. The presence or absence of type II collagen probably relates to different levels of compressive loading. No fibrocartilaginous menisci were found in normal joints and those described previously are regarded as synovial folds.

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.

A dynamic biomechanical study of scapholunate ligament sectioning

A biomechanical study was performed on fresh cadaver forearms to investigate the role of the scapholunate interosseous ligament in carpal stability. Scaphoid and lunate motion and radiocarpal and ulnocarpal pressure patterns were continually monitored while the wrist was moved physiologically. Prior to ligament sectioning, it was found that the position of the scaphoid and lunate were dependent on both the wrist position and the direction of wrist motion. Sectioning the scapholunate interosseous ligament caused increased scaphoid flexion, scaphoid pronation, and lunate extension. Pressure in the radiocarpal and ulnocarpal joint was redistributed following ligament sectioning. These findings support the clinical impression that the scapholunate interosseous ligament is an important stabilizer of the scaphoid and lunate.

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.