Comparison of Lag Versus Nonlag Screw Fixation for Long Oblique Proximal Phalanx Fractures: A Biomechanical Study.

PURPOSE: To compare lag versus nonlag screw fixation for long oblique proximal phalanx (P1) fractures in a cadaveric model of finger motion via the flexor and extensor tendons. METHODS: We simulated long oblique P1 fractures with a 45° oblique cut in the index, middle, and ring fingers of 4 matched pairs of cadaveric hands for a total of 24 simulated fractures. Fractures were stabilized using 1 of 3 techniques: two 1.5-mm fully threaded bicortical screws using a lag technique, two 1.5-mm fully threaded bicortical nonlag screws, or 2 crossed 1.14-mm K-wires as a separate control. The fixation method was randomized for each of the 3 fractures per matched-pair hand, with each fixation being used in each hand and 8 total P1 fractures per fixation group. Hands were mounted to a custom frame where a computer-controlled, motor-driven, linear actuator powered movement of the flexor and extensor tendons. All fingers underwent 2,000 full flexion and extension cycles. Maximum interfragmentary displacement was continuously measured using a differential variable reluctance transducer. Our primary outcome was the difference in the mean P1 fragment displacement between lag and nonlag screw fixation at 2,000 cycles. RESULTS: The observed differences in mean displacement between lag and nonlag screw fixation were not statistically significant throughout all time points. A two one-sided test procedure for paired samples confirmed statistical equivalence in the fragment displacement between these fixation methods at all time points, including the primary end point of 2,000 cycles. CONCLUSIONS: Nonlag screws provided equivalent biomechanical stability to lag screws for simulated long oblique P1 fractures during cyclic testing in this cadaveric model. CLINICAL RELEVANCE: Fixation of long oblique P1 fractures with nonlag screws has the potential to simplify treatment without sacrificing fracture stability during immediate postoperative range of motion.

Measurement of Outlet Pressures Favors Rib Resection for Decompression of Thoracic Outlet Syndrome.

BACKGROUND: When conservative therapy for thoracic outlet syndrome fails, scalenectomy with or without first-rib resection (FRR) is the treatment of choice. We measured pressure in the costoclavicular space before and after FRR at time of neurogenic thoracic outlet syndrome release to evaluate whether FRR is required to completely decompress the costoclavicular space. METHODS: Using a supraclavicular exposure for anterior-middle scalenectomy with FRR, costoclavicular space pressures were measured using a balloon catheter with the patient's arm in neutral anatomic position, secondarily, the arm abducted and externally rotated. Pressures were recorded in both arm positions before scalenectomy, after scalenectomy, and after FRR. Paired Student's t test was used to compare differences in group means for paired samples. Patient-reported outcomes were reported using the Derkash classification and quick disabilities of the arm, shoulder, and hand (qDASH) questionnaire. RESULTS: Fifteen patients (16 cases) surgically treated for neurogenic thoracic outlet syndrome were included in this retrospective study. There was no significant difference in pressure change between arm positions before scalenectomy (161.56 ± 71.65 mm Hg difference) or after scalenectomy (148.5 ± 80.24 mm Hg difference). There was a significant difference in pressure change between post-scalenectomy and post-FRR arm positions; mean pressure change between arm positions after FRR was 50.56 ± 40.28 mm Hg. Mean postoperative qDASH score was 20 ± 23.2. All patients reported improvement in symptoms and functional status. CONCLUSIONS: Supraclavicular first rib resection for management of neurogenic thoracic outlet syndrome can be safely performed with favorable outcomes. The pressure increase in the costoclavicular space caused by arm abduction and external rotation was significantly reduced only after FRR, raising concerns about potential incomplete costoclavicular space decompression with scalenectomy alone for neurogenic thoracic outlet syndrome management.

Suture-Button Reconstruction of the Interosseous Membrane.

BACKGROUND: Reconstruction of the interosseous membrane (IOM) may play a role in the treatment of acute and chronic longitudinal forearm instability. Several reconstruction techniques have been proposed. Suture-button reconstruction is attractive because it obviates donor site morbidity and is relatively easy to perform. How this method compares to its alternatives, however, is unknown. MATERIALS AND METHODS: We review literature describing reconstruction of the forearm axis. We describe how we perform suture-button reconstruction of the IOM, summarize our previously published biomechanical data on the subject, and offer a case report. DESCRIPTION OF TECHNIQUE: A suture-button is implanted so as to approximate the course of the interosseous ligament. This may be accomplished percutaneously, or when grafting is desired, through an open approach. RESULTS: Data informing the choice of one reconstruction technique over another consist mostly of biomechanical studies and a small number of case reports. CONCLUSIONS: Suture-button reconstruction of the IOM may encourage anatomic healing of acute forearm axis injuries especially as an adjunct to radial head replacement or repair. Chronic injuries may benefit from a combination suture-button graft construct and ulnar shortening osteotomy.

Effect of anterior versus posterior in situ decompression on ulnar nerve subluxation.

We sought to determine the effect anterior versus posterior in situ decompression with 360° external neurolysis on ulnar nerve subluxation. Ten cadaveric specimens were used, with anterior release performed on 5 specimens and posterior release the other 5 specimens. Each specimen was released for 4 cm centered over the cubital tunnel followed by 12 cm, 20 cm, and 20 cm with 360° external neurolysis. After release, the elbow was brought through a range of motion from 0° to 140° of flexion. Compared with posterior release, anterior release demonstrated significantly more total subluxation of the ulnar nerve for all release types from 80° to 120° of flexion (P<.05). At 140° of flexion, the 4-cm release, the 12-cm release, and the 20-cm release with 360° external neurolysis also demonstrated significantly more total subluxation with anterior release (P<.05). Ulnar nerve subluxation was significantly lower with posterior release, compared with anterior release for limited and complete in situ decompression.

Unusual case of cutaneous and synovial Paecilomyces lilacinus infection of hand successfully treated with voriconazole and review of published literature.

Paecilomyces lilacinus infection is rare and is found worldwide. The majority of infections occur in immunocompromised people. Among immunocompetent patients, cutaneous infections are the second most common site of infection but are difficult to treat because of antifungal resistance. We report a case of hand cutaneous involvement with synovitis in an immunocompetent patient that improved after treatment with oral voriconazole. To the best of our knowledge, there are only five published cases of cutaneous P.lilacinus infection, all in immunocompromised patient, treated with oral voriconazole. We review all previously reported cases.

Restoration of longitudinal forearm stability using a suture button construct.

PURPOSE: This study proposed a method of restoring the longitudinal stability of the forearm provided by the central band of the interosseous membrane (IOM) by using a percutaneously placed suture button construct. We hypothesized that supporting the forearm IOM with a suture button construct would restore longitudinal stability in a cadaveric model of the Essex-Lopresti lesion. METHODS: We assessed 7 adult cadaver upper extremities radiographically for evidence of previous elbow, forearm, or wrist fracture. Each limb was mounted onto a materials testing system with the elbow held at 90° and the forearm in neutral. The intact specimen was loaded cyclically at 134 N to determine the native mobility of the forearm segment. Each specimen was tested after each of the following steps: radial head removal, transection of the IOM, and suture button construct reconstruction of the IOM. After the final reconstruction, each specimen was examined for forearm range of motion and evidence of neurovascular injury. RESULTS: Removal of the radial head and sectioning of the IOM sequentially increased average proximal migration of the radius by 3.6 and 7.1 mm, respectively. After reconstruction with the suture button construct, the IOM was restored to the intact state with only the radial head removed. Forearm rotation was not compromised by the reconstruction, and there was no evidence of neurovascular injury in any specimen. CONCLUSIONS: A percutaneously placed suture button construct can restore the longitudinal stability provided by an IOM. The method described did not limit forearm rotation. We encountered no neurovascular injury in the specimens tested in this series. This construct may be an effective adjunct when combined with bony reconstruction to treat longitudinal forearm axis injuries.

Complications of small joint arthroplasty.

Arthritis in the small joints of the hand can be treated with arthrodesis or arthroplasty. Arthrodesis has known risks of infection, pain, and nonunion. Distal interphalangeal (DIP) arthroplasty has been successful in preserving motion and alleviating pain for distal DIP, proximal interphalangeal, and metacarpophalangeal joints. Unfortunately, complications arise that limit the success of surgery. Silicone implants have been reliable for many years but still present with the risks of infection, implant breakage, stiffness, and pain. Newer implant designs may limit some of these complications, but present with unique problems such as dislocations and loosening. It is not yet clear as to which type of implant provides the most reliable results, although implant arthroplasty appears to give better function than arthrodesis. Silicone arthroplasty does not lead to silicone synovitis and is a reliable procedure. Pyrocarbon implants are showing some promise, particularly in the osteoarthritic patient.

Release of the transverse carpal ligament alone is associated with elevated pressure beneath the distal volar forearm fascia in a cadaver model of carpal tunnel syndrome.

PURPOSE: The purpose of this study is to determine whether release of the distal volar forearm fascia (DVFF) is necessary at the time of median nerve decompression for carpal tunnel syndrome. METHODS: Five fresh-frozen cadaver specimens were mounted vertically with the hand dependent and a 2.27-kg weight suspended from the fingers. A pressure sensor wire was used to measure pressures starting just distal to the transverse carpal ligament (TCL). The wire was withdrawn proximally in 5-mm increments and into the forearm until pressure was below 10 mm Hg. An incision in the forearm was extended distally until the pressure sensor was found. The distance from this point to the distal volar wrist crease was measured. The TCL was released, keeping the DVFF intact, and the experiment was repeated. Paired t-tests determined whether there were statistically significant differences between measurements before and after TCL release. RESULTS: Average peak pressure under the intact TCL was 57.8 +/- 10.1 mm Hg. Average peak pressure under the DVFF with the TCL intact was 61.2 +/- 43.6 mm Hg. Following release of the TCL, average peak pressure beneath the TCL significantly decreased to 14.0 +/- 9.0 mm Hg, whereas average peak pressure at the intact DVFF increased to 64.8 +/- 48.7 mm Hg. Average locations where DVFF pressure became less than 10 mm Hg with an intact TCL and with released TCL were 4.30 +/- 1.8 cm and 4.00 +/- 1.8 cm proximal to the distal volar wrist crease, respectively. There was no significant difference between DVFF pressures before or after TCL release. CONCLUSIONS: In a cadaver model of carpal tunnel syndrome, release of the TCL alone is associated with persistent pressures >30 mm Hg in the region of the DVFF. Release of the TCL did not significantly change the location of the pressure drop-off under the DVFF.

Biomechanical stability of a volar locking-screw plate versus fragment-specific fixation in a distal radius fracture model.

Eight matched pairs of cadaveric radii were osteotomized by removing a 4-mm dorsal wedge of bone at the level of the sigmoid notch designed to simulate dorsal comminution. They were then fixed with either a volar locking-screw plate or fragment-specific fixation. All constructs underwent biomechanical testing in a custom-designed, custom-fabricated 4-point bending device. No statistically significant difference in stiffness was noted between the groups. Linear displacement and angulation at the osteotomy site were significantly less in the group with fragment-specific fixation at loads expected to be encountered during postoperative rehabilitation. Angulation at the osteotomy site was significantly less in the locking-screw plate group at higher loads.

Lateral approach to proximal interphalangeal joint implant arthroplasty.

Arthroplasty of the proximal interphalangeal joint is indicated for arthritic conditions that fail to respond to conservative treatment. This article describes the lateral approach for the insertion of a proximal interphalangeal joint implant arthroplasty. Clinical experience has confirmed good results in the nonlaborer with arthroplasty of all the digits. Ten surgeries have averaged 68 degrees of motion with a range from 50 degrees to 80 degrees . No patient has required a revision 3 years after surgery.

Lesions and tumors of the carpus.

Lesions and tumors of the carpus are usually identified radiographically during a routine workup for wrist pain. Although most of these entities are benign, a failure to appreciate their presence may delay diagnosis and treatment. More importantly, a small subset of these tumors may be quite aggressive, and early recognition can spare the patient the morbidity of late sequelae such as pathologic fracture, progressive wrist arthrosis, or even tumor metastasis. This article provides current information on how to identify, differentiate, and treat the varied lesions and tumors that may be discovered in the carpus.

Dynamic lumbrical muscle transfer for correction of posttraumatic extensor tendon subluxation.

Posttraumatic ulnar subluxation of the extensor tendon over the metacarpal head results from rupture of the radial sagittal fibers. The patient will complain of limited digital extension and pain. Various techniques have been described to correct the disorder by either reefing the sagittal fibers or using a slip of extensor tendon around the radial collateral ligament. Unfortunately, these techniques are either technically not feasible, reefing of the sagittal fibers, or result in significant stiffness, using a strip of extensor tendon. The author describes an extraarticular technique which uses a dynamic muscle transfer that is synergistic with metacarpophalangeal flexion.

Biomechanical stability of a fixed-angle volar plate versus fragment-specific fixation system: cyclic testing in a C2-type distal radius cadaver fracture model.

PURPOSE: To compare the biomechanical stability of 2 recently introduced fixation systems in an intra-articular, dorsal comminution distal radius fracture model. METHODS: AO/ASIF type C2 fractures were simulated in 10 matched pairs of fresh-frozen cadaveric arms randomized between fixed-angle volar plate and fragment-specific fixation systems. Specimens were loaded in extension cyclically for 2,000 repetitions followed by a single cycle to failure. Initial, intermediate, and final stiffness values and failure load values were obtained and compared. RESULTS: Both systems were able to sustain physiologic cyclic loading. The fragment-specific system was significantly stiffer than the fixed-angle volar plate system for the ulnar segment in both the precycle and postcycle values. No other comparisons were significant with respect to stiffness. No significant difference in load to failure was found between the systems with respect to ulnar, radial, or overall fragment displacement. CONCLUSIONS: Both fixed-angle volar plate and fragment-specific fixation systems performed comparably in a simulated early postoperative motion protocol. Fragment-specific fixation had improved stiffness characteristics only with respect to the smaller ulnar-sided fragment.

Radiographic parameters of increased carpal tunnel pressure with progressive wrist distraction: a cadaveric study.

PURPOSE: Increased carpal canal pressure associated with external fixation has been noted as a potential source of complications but no correlated clinical observation has been identified. We hypothesized that there would be a significant change in midcarpal distance and modified carpal height index with increasing distraction across the wrist joint and that these changes would correlate with pressure increases. METHODS: Thirteen cadaveric upper extremities were mounted vertically using 2 half pins in the midradius. Using a previously reported technique, we introduced a balloon-tipped catheter attached to a transducer into the carpal canal for pressure measurement. As weights were hung from the middle finger to create distraction across the carpus, pressure measurements and radiographs of the wrist were taken simultaneously. This sequence was performed for 4.50 kg of distraction in 0.45-kg increments and at 6.80 and 9.07 kg of distraction with the wrist in neutral position. Changes in midcarpal distance and modified carpal height index were calculated and comparisons were made with the Student t test. A 2-tailed Pearson correlation was used to determine whether there was a correlation between carpal canal pressure and radiographic indicators. Significance was set at p

Carpal canal pressure of the distracted wrist.

PURPOSE: This study was conducted to study the effect of distraction across the wrist joint on carpal canal pressure. METHODS: Ten cadaver specimens were mounted vertically in neutral forearm rotation by 2 half pins that transfixed the radius and ulna. The wrist joint was distracted by suspending weights from the middle finger. A balloon-tipped catheter, percutaneously introduced into the carpal canal and connected to a transducer, was used to measure carpal canal pressure. The carpal canal pressure was measured at 0 to 4.54 kg of distraction in 0.45-kg increments and at 6.81 kg and 9.08 kg of distraction. Three wrist positions were tested: neutral, 30 degrees of flexion, and 30 degrees of extension. RESULTS: Highly linear direct relationships between wrist distraction force and carpal canal pressure over baseline were observed in all positions of the wrist. Statistically significant increases in carpal canal pressure over baseline were observed at a wrist distraction force of 2.27 kg or more with the wrist in neutral position, at 1.82 kg or more with the wrist in 30 degrees of extension, and at 4.09 kg or more with the wrist in 30 degrees of flexion. At each level of wrist distraction force of 3.63 kg or less the carpal canal pressure of the extended wrist was significantly higher than that of the wrist in neutral position. At each level of wrist distraction force 4.54 kg or less the carpal canal pressure of the extended wrist was significantly higher than that of the flexed wrist. No statistically significant differences were observed at any level of wrist distraction force between carpal canal pressures in the neutral and flexed positions of the wrist. CONCLUSIONS: Distraction across the wrist joint causes a statistically significant highly linear increase in carpal canal pressure. The position of the distracted wrist also has a considerable effect on carpal canal pressure, with the extended position associated with the largest increases in carpal canal pressure and the flexed position with the smallest increases in carpal canal pressure.

Long-term results of surgical management of proximal interphalangeal joint contracture.

To evaluate the long-term results of surgical treatment of proximal interphalangeal (PIP) joint contractures, 68 PIP joints were retrospectively reviewed with a minimum follow-up period of 24 months. Preoperative and intraoperative factors were studied for outcomes and subjected to statistical analysis. Among the total group the average improvement was 7.5 degrees. When grouped by diagnosis into simple (less severe diagnoses) and complex (more severe diagnoses) the average degrees gained were 17.2 degrees and 0.5 degrees, respectively. The statistically significant factors that were identified that affected results were age, number of prior procedures, preoperative flexion, removal of an exostosis, number of structures addressed, and preoperative arc of motion. The second surgery (joints requiring repeat release or salvage procedure) rates were 35% overall, 29% simple, and 39% complex; the difference was not significant. The best surgical candidate is a patient younger than 28 years with a less severe diagnosis and who has preoperative maximum flexion measurement < 43 degrees.

Diagnosis and treatment of post-traumatic medial and lateral elbow ligament incompetence.

Elbow instability may occur secondary to soft tissue or bony injuries. Predictable patterns of instability do occur. Identification of disrupted osseous or ligamentous constraints allows for an algorithmic and predictable treatment plan. Maintaining a high index of suspicion allows early recognition and treatment of elbow instability. Treatment based on recognized principles is the key to preventing recurrent instability and late arthrosis while maintaining functional elbow motion.