Biomedical subjects

Edward Diao

Publications and source records attributed to Edward Diao.

12 recordsLinked to original sources

PubMed2006

Finger flexor motor control patterns during active flexion: an in vivo tendon force study.

An in vivo tendon force measurement system was used to evaluate index finger flexor motor control patterns during active finger flexion. During open carpal tunnel release surgery (N=12) the flexor digitorum profundus (FDP) and flexor digitorum superficilias (FDS) tendons were instrumented with buckle force transducers and participants performed finger flexion at two different wrist angles (0 degrees or 30 degrees ). During finger flexion, there was concurrent change of metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joint angles, but the FDP and FDS tendon force changes were not concurrent. For the FDS tendon, no consistent changes in force were observed across participants at either wrist angle. For the FDP tendon, there were two force patterns. With the wrist in a neutral posture, the movement was initiated without force from the finger flexors, and further flexion (after the first 0.5s) was carried out with force from the FDP. With the wrist in a flexed posture, the motion was generally both initiated and continued using FDP force. At some wrist postures, finger flexion was initiated by passive forces which were replaced by FDP force to complete the motion.

Carpal Tunnel Syndrome↗

PubMed2006

In vivo flexor tendon forces increase with finger and wrist flexion during active finger flexion and extension.

The effects of different hand motions and positions used during early protected motion rehabilitation on tendon forces are not well understood. The goal of this study was to determine in vivo forces in human flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons of the index finger during active unresisted finger flexion and extension. During open carpal tunnel surgery (n = 12), flexor tendon forces were acquired with buckle force transducers, and finger positions were recorded on video while subjects actively flexed and extended the fingers at two different wrist angles. Mean in vivo FDP tendon forces varied between 1.3N +/- 0.9 N and 4.0 N +/- 2.9 N while mean FDS tendon forces ranged from 1.3N +/- 0.5 N to 8.5 N +/- 10.7 N. FDP force increased with active finger flexion at both wrist angles of 0 degrees or 30 degrees flexion. FDS force increased with finger flexion when the wrist was in 30 degrees flexion, but was unchanged when the wrist was in 0 degrees of flexion. Tendon forces were similar regardless of whether the fingers were moving in the flexion or extension direction. Active finger flexion and extension with the wrist at 0 degrees and 30 degrees flexion may be used during early rehabilitation protocols with limited risk of repair rupture. This risk can be further decreased for a FDS tendon repair by reducing wrist flexion angle.

Adult↗

PubMed2006

Kienböck's disease: an approach to treatment.

Since its description in 1910, Kienböck's disease has continued to be a difficult problem for clinicians as well as patients. An incomplete understanding of the etiology as well as the natural history of the disease has led to an assortment of surgical treatment options. The authors present a review of Kienböck's disease and the theories behind different surgical interventions, as well as their current approach to treatment of patients with Kienböck's disease.

Algorithms↗

PubMed2006

A device for zone-II flexor tendon repair. Surgical technique.

BACKGROUND: The stainless-steel Teno Fix tendon-repair device has improved biomechanical characteristics compared with those of suture repair, and it was well tolerated in a canine model. The purpose of this study was to compare the Teno Fix with suture repair in a clinical setting. METHODS: Sixty-seven patients with isolated zone-II flexor tendon injury were randomized to be treated with a Teno Fix or a four-stranded cruciate suture repair. There were eighty-five injured digits: thirty-four were treated with the Teno Fix, and fifty-one served as controls. A modified leinert rehabilitation technique was employed, with active flexion starting at four weeks postoperatively. Patients were followed for six months by blinded observers who determined the range of motion, Disabilities of the Arm, Shoulder and Hand (DASH) score, pinch and grip strength, and pain score on a verbal scale and assessed swelling and neurologic recovery. Adverse outcomes, including device migration and rupture, were monitored at frequent intervals. RESULTS: Nine of the fifty-one suture repairs ruptured, whereas none of the Teno Fix repairs ruptured (p < 0.01). Five of the nine ruptures were caused by resistive motion against medical advice. There were no differences between the two groups in terms of range of motion, DASH score, pinch and grip strength, pain, swelling, or neurologic recovery. The Teno Fix group had slightly slower resolution of pain and swelling compared with the control group. Of the patients who were available for follow-up at six months, sixteen of the twenty-four treated with a Teno Fix repair and nineteen of the twenty-seven treated with a control repair had a good or excellent result. One Teno Fix device migrated and extruded secondary to a wound infection. Of all eighty-five digits that were operated on, four were thought to have tendons of inadequate size to accommodate the device and nine were deemed to have inadequate exposure to allow placement of the anchors. CONCLUSIONS: The Teno Fix is safe and effective for flexor tendon repair if the tendon size and exposure are sufficient. Tendon repairs with the Teno Fix have lower rupture rates and similar functional outcomes when compared with conventional repair, particularly in patients who are non-compliant with the rehabilitation protocol.

Equipment Design↗

PubMed2005

Proximal row carpectomy.

Proximal row carpectomy is extremely useful as a wrist reconstructive technique for cases of degenerative joint arthritis of the radiocarpal joint cause by scapholunate advanced collapse, scapholunate advanced collapse, schaphoid nonunion advanced collapse, trans-scaphoid perilunate fracture dislocations, lunate dislocations, and Kienböck disease. It should be selected with caution for patients younger than 35 years old. The procedure can be performed with or without temporary internal fixation with with Kirschner wires, and adjunctive techniques of dorsal capsule interposition, proximal capitate excision, and radial styloidectomy can be used. The longevity of the operation is good, but the patient should be informed preoperatively that secondary procedures may be required. Based on historical series, these procedures have included addition have included of radial styloidectomy when this has not been performed at the index procedure, revision of the surgery with capitate debridement or conversion to total wrist arthodesis. Conversion of proximal row carpectomy to total wrist arthoplasty with implants can be contemplated in selected patient particularly as newer implants are designed. The technique the senior author has used on occasion has been to perform revision surgery on those patients who have chronic pain who might need further debridement of the radius in the radial styloid, the proximal capitate, or evaluation of the integrity of the interposition.

Adult↗

PubMed2005

Carpal tunnel pressure alters median nerve function in a dose-dependent manner: a rabbit model for carpal tunnel syndrome.

BACKGROUND: An in vivo animal model for carpal tunnel syndrome (CTS) is presented which allows for graded application of pressure to the median nerve within the carpal canal. We hypothesized that such pressure would cause electrophysiologic changes in the median nerve in a dose-related manner, with NCS/EMG changes consistent with CTS in humans. METHODS: In 40 New Zealand white rabbits, ranging from 2 to 2.5 kg, angioplasty catheters were placed in the carpal tunnel in the forepaws and pressures ranging from 50 to 80 mmHg applied to one side while the contralateral side served as the control and remained uninflated. Pressure was applied until a 15% increase in distal motor latency was obtained for 2 consecutive weeks by nerve conduction studies. RESULTS: All the experimental limbs exhibited a 15% increase in distal motor latency. None of the control limbs showed a significant increase in distal motor latency. In the experimental animals the 15% delay was achieved in approximately 4-5 weeks in the 50-70 mmHg groups and in approximately 1 week in the 80 mmHg group. CONCLUSION: This new animal model for CTS demonstrates a direct cause and effect relationship between carpal tunnel pressure and median nerve dysfunction. We anticipate that this in vivo model with clinically relevant outcomes will facilitate identification of injury mechanisms, and will serve as a basis for future development of novel interventions and treatments.

Animals↗

PubMed2005

Device for zone-II flexor tendon repair. A multicenter, randomized, blinded, clinical trial.

BACKGROUND: The stainless-steel Teno Fix tendon-repair device has improved biomechanical characteristics compared with those of suture repair, and it was well tolerated in a canine model. The purpose of this study was to compare the Teno Fix with suture repair in a clinical setting. METHODS: Sixty-seven patients with isolated zone-II flexor tendon injury were randomized to be treated with a Teno Fix or a four-stranded cruciate suture repair. There were eighty-five injured digits: thirty-four were treated with the Teno Fix, and fifty-one served as controls. A modified Kleinert rehabilitation technique was employed, with active flexion starting at four weeks postoperatively. Patients were followed for six months by blinded observers who determined the range of motion, Disabilities of the Arm, Shoulder and Hand (DASH) score, pinch and grip strength, and pain score on a verbal scale and assessed swelling and neurologic recovery. Adverse outcomes, including device migration and rupture, were monitored at frequent intervals. RESULTS: Nine of the fifty-one suture repairs ruptured, whereas none of the Teno Fix repairs ruptured (p < 0.01). Five of the nine ruptures were caused by resistive motion against medical advice. There were no differences between the two groups in terms of range of motion, DASH score, pinch and grip strength, pain, swelling, or neurologic recovery. The Teno Fix group had slightly slower resolution of pain and swelling compared with the control group. Of the patients who were available for follow-up at six months, sixteen of the twenty-four treated with a Teno Fix repair and nineteen of the twenty-seven treated with a control repair had a good or excellent result. One Teno Fix device migrated and extruded secondary to a wound infection. Of all eighty-five digits that were operated on, four were thought to have tendons of inadequate size to accommodate the device and nine were deemed to have inadequate exposure to allow placement of the anchors. CONCLUSIONS: The Teno Fix is safe and effective for flexor tendon repair if the tendon size and exposure are sufficient. Tendon repairs with the Teno Fix have lower rupture rates and similar functional outcomes when compared with conventional repair, particularly in patients who are noncompliant with the rehabilitation protocol.

Adult↗

PubMed2004

In vivo forces generated by finger flexor muscles do not depend on the rate of fingertip loading during an isometric task.

Risk factors for activity-related tendon disorders of the hand include applied force, duration, and rate of loading. Understanding the relationship between external loading conditions and internal tendon forces can elucidate their role in injury and rehabilitation. The goal of this investigation is to determine whether the rate of force applied at the fingertip affects in vivo forces in the flexor digitorum profundus (FDP) tendon and the flexor digitorum superficialis (FDS) tendon during an isometric task. Tendon forces, recorded with buckle force transducers, and fingertip forces were simultaneously measured during open carpal tunnel surgery as subjects (N=15) increased their fingertip force from 0 to 15N in 1, 3, and 10s. The rates of 1.5, 5, and 15N/s did not significantly affect FDP or FDS tendon to fingertip force ratios. For the same applied fingertip force, the FDP tendon generated more force than the FDS. The mean FDP to fingertip ratio was 2.4+/-0.7 while the FDS to tip ratio averaged 1.5+/-1.0 (p<0.01). The fine motor control needed to generate isometric force ramps at these specific loading rates probably required similar high activation levels of multiple finger muscles in order to stabilize the finger and control joint torques at the force rates studied. Therefore, for this task, no additional increase in muscle force was observed at higher rates. These findings suggest that for high precision, isometric pinch maneuvers under static finger conditions, tendon forces are independent of loading rate.

Adult↗

PubMed2004

Entrapment neuropathies: pathophysiology and pathogenesis.

A number of theories of pathogenesis of entrapment neuropathy, due to repeated loading, have been proposed and these theories are being actively explored with animal models. Tubes placed loosely around peripheral nerves cause delayed onset, chronic pain and changes in nerve morphology including nerve sprouting. Balloons placed around or adjacent to the nerve and inflated to low pressures, rapidly produce endoneurial edema and a persistent increase in intraneural pressure. The same models demonstrate long-term changes such as demyelination and fibrosis. The applied pressure causes a decrement in nerve function and abnormal morphology in a dose-dependent manner that appears to be linked to the amount of endoneurial edema. A new model involving involuntary, repetitive fingertip loading for 6 h per week for 4 weeks has caused slowing of nerve function at the wrist similar to that seen in patients with carpal tunnel syndrome. These models have the potential to reveal the mechanisms of injury at the cellular and biochemical level and address questions about the relative importance of various biomechanical factors (e.g. peak force, mean force, force rate, duty cycle, etc.). In addition, these models will allow us to evaluate various prevention, treatment and rehabilitation protocols.

Animals↗

PubMed2003

Scaphoid kinematic behavior after division of the transverse carpal ligament.

PURPOSE: The effect that carpal tunnel release (CTR) has on scaphoid motion has not been reported. Accordingly the purpose of this study was to determine the flexion/extension behavior of the scaphoid during global wrist radial/ulnar deviation before and after division of the transverse carpal ligament (TCL). METHOD: In this study we examined the in vitro kinematics of the scaphoid during wrist deviation in 6 cadaver forearms both before and after the division of the TCL using a computerized camera monitoring system. The specimens were evaluated in 13 different positions, from 20 degrees of radial deviation to 40 degrees of ulnar deviation at increments of 5 degrees. RESULTS: The data indicate that the difference in scaphoid position after TCL division is statistically significant when the wrist is in ulnar deviation of 15 degrees or greater. In addition a significant difference in scaphoid extension between pre- and post-TCL division conditions was found at 5 degrees of radial deviation as well as at 5 degrees or more of ulnar deviation and increased with increasing ulnar deviation. CONCLUSIONS: Scaphoid kinematics are altered considerably in radial-ulnar deviation after division of the TCL. This alteration may have long-term consequences and contribute to commonly seen post-CTR symptoms.

Analysis of Variance↗

PubMed2003

Dorsal and palmar material properties of the adult human flexor profundus tendon in Zone II.

Nineteen fresh frozen adult human flexor digitorum profundus (FDP) tendons in Zone II were studied to compare the differences in material properties between the dorsal (dFDP) and palmar (pFDP) side of each tendon biomechanically, biochemically and histologically. We have found that tissue from the dorsal side of each flexor tendon has (1) greater strength; (2) less collagen crosslinking (hydroxypyridinium); and (3) a larger single bundle cross-sectional area than tissue from the palmar side of the same tendon. These data clearly demonstrate that the dorsal and palmar sides of the adult human (FDP) tendon in Zone II differ materially. These differences suggest that there may be biomechanical advantages in placing core sutures dorsally when repairing flexor tendons, a technique that we have previously described.

Adult↗

PubMed2002

Single-portal endoscopic carpal tunnel release compared with open release : a prospective, randomized trial.

BACKGROUND: Carpal tunnel syndrome is a common condition causing hand pain and numbness. Endoscopic carpal tunnel release has been demonstrated to reduce recovery time, although previous studies have raised concerns about an increased rate of complications. The purpose of this prospective, randomized study was to compare open carpal tunnel release with single-portal endoscopic carpal tunnel release. METHODS: A prospective, randomized, multicenter center study was performed on 192 hands in 147 patients. The open method was performed in ninety-five hands in seventy-two patients, and the endoscopic method was performed in ninety-seven hands in seventy-five patients. All of the patients had clinical signs or symptoms and electrodiagnostic findings consistent with carpal tunnel syndrome and had not responded to, or had refused, nonoperative management. Follow-up evaluations with use of validated outcome instruments and quantitative measurements of grip strength, pinch strength, and hand dexterity were performed at two, four, eight, twelve, twenty-six, and fifty-two weeks after the surgery. Complications were identified. The cost of the procedures and the time until return to work were recorded and compared between the groups. RESULTS: During the first three months after surgery, the patients treated with the endoscopic method had better Carpal Tunnel Syndrome Symptom Severity Scores, better Carpal Tunnel Syndrome Functional Status Scores, and better subjective satisfaction scores. During the first three months after surgery, they also had significantly (p < 0.05) greater grip strength, pinch strength, and hand dexterity. The open technique resulted in greater scar tenderness during the first three months after surgery as well as a longer time until the patients could return to work (median, thirty-eight days compared with eighteen days after the endoscopic release). No technical problems with respect to nerve, tendon, or artery injuries were noted in either group. There was no significant difference in the rate of complications or the cost of surgery between the two groups. CONCLUSION: Good clinical outcomes and patient satisfaction are achieved more quickly when the endoscopic method of carpal tunnel release is used. Single-portal endoscopic surgery is a safe and effective method of treating carpal tunnel syndrome.

Adult↗