In vitro biomechanical analysis of suture methods for flexor tendon repair.

This study was designed to compare five different suture methods that are used clinically for tendon repair. The flexor digitorum profundus tendons from the digits of adult mongrel dogs and adult human cadavers were used as models. The tendons in zone II of the hand, defined as the region from the distal palmar crease to the insertion of the flexor digitorum superficialis tendon at the middle phalanx, were transected and then were repaired by one of the suture methods developed by Kessler, Tsuge, Tajima, Savage, or Lee. The gliding function and tensile properties of the repaired tendons were evaluated biomechanically at time zero. The Tajima and Savage methods produced better gliding function than the other techniques. In the canine specimens that had been repaired by one of these two methods, the rotation of the distal interphalangeal joint was more than 60% of the rotation of the canine control specimens; only the Savage technique produced a rotation 124% that of the human control specimens. After the Tajima repair, the rotation of the proximal interphalangeal joint was 113% that of the canine control specimens and 157% that of the human controls. In the canine specimens that had had the Tajima or Savage repair, excursion of the tendon was greater than 55% that of the controls. The tendons repaired by the Savage method tolerated a significantly higher ultimate load to failure (14 and 25% that of the canine and human control specimens, respectively) than the other methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Autogenous intrasynovial and extrasynovial tendon grafts: an experimental study of pro alpha 1(I) collagen mRNA expression in dogs.

On the basis of recent evidence that the healing processes of tendon grafts are donor-tissue specific, in situ hybridization, using a 372 bp cDNA fragment complementary to a portion of pro alpha 1(I) collagen mRNA, was utilized to compare the cellular responses to transplantation exhibited by autogenous intrasynovial and extrasynovial flexor tendon grafts. Intrasynovial and extrasynovial tendons from the hindpaw were transferred to synovial sheaths in the forepaw of 12 mongrel dogs (24 tendons) and treated with immediate controlled passive motion. The tendon grafts were harvested at 2, 4, and 6 weeks, and each was divided into a proximal, central (8 mm), and distal portion. Sections from the central portion were embedded in paraffin and subjected to in situ hybridization, autoradiography, and staining; levels of procollagen mRNA then were assessed by microscopic examination. The two types of tendon grafts exhibited different levels of pro alpha 1(I) collagen mRNA expression at all three time points. Intrasynovial tendon grafts displayed no areas of increased type-I procollagen mRNA at 2, 4, and 6 weeks. The extrasynovial tendon grafts displayed increased surface levels of type-I procollagen mRNA at 2 and 4 weeks; the levels decreased to background levels by 6 weeks. The high levels of procollagen mRNA exhibited by the extrasynovial grafts suggest increased collagen synthetic activity, indicative of a cellular response to injury, whereas the preservation of low levels of expression in the intrasynovial grafts may signify a less inflammatory cellular response.

Amputation after extremity injury.

Extremity injury is a significant cause of morbidity and mortality in the trauma patient. The decision to amputate is a difficult one to make in a patient population still in the productive years of life. At the University of Louisville Hospital from 1976 to 1984, 37 patients with traumatic extremity injury required amputation. Ninety percent of these injuries were to the lower extremities. A decision for amputation was based on the absence of neurovascular function, the presence of fracture of the involved extremity, the presence of a large soft tissue defect, and the presence of severe contamination. Prompt amputation of such severely damaged limbs may be preferable to attempts at salvage. Early amputation offers the opportunity for prosthetic replacement and good long-term functional recovery.

Sympathetic maintained pain (causalgia) associated with a demonstrable peripheral-nerve lesion. Operative treatment.

Nine patients who had sympathetic maintained pain (causalgia) and a total of ten identifiable lesions involving peripheral nerves were managed with a continuous sympathetic block; repair, reconstruction, or lysis of the involved nerve, or a combination of these procedures; and rotation of a muscle flap over the nerve in an attempt to enhance the blood supply in the area and to reduce scarring in the region surrounding the nerve. The lesions were located in the median nerve at the wrist in five of the patients; in both the ulnar nerve at the elbow and the median nerve at the wrist in one; and in the ulnar nerve at the elbow, the radial digital nerve of the index finger, and the posterior tibial nerve near the ankle in one patient each. The average duration of symptoms before treatment was seventeen weeks. All nine patients had clinical findings that were considered diagnostic of sympathetic maintained pain or causalgia. Electrophysiological evidence of dysfunction of one peripheral nerve or more was found in the eight patients who had an electromyogram and a nerve-conduction study. In all nine patients, the causalgic pain diminished within the first seventy-two hours after the operation, and none of the patients had had any recurrence of symptoms at an average of forty-eight months. Although all of the patients had some residual limitation of function, all had improvement after this treatment, and the improvement was maintained.

Correlation of the findings of magnetic resonance imaging with those of bone biopsy in patients who have stage-I or II ischemic necrosis of the femoral head.

A prospective study was undertaken to determine the diagnostic accuracy of magnetic resonance imaging in the evaluation of a symptomatic hip for which a diagnosis of early ischemic necrosis of the femoral head was suspected. Fifteen patients (sixteen symptomatic hips), for whom the findings of magnetic resonance imaging were consistent with a diagnosis of osteonecrosis of the femoral head, had a core decompression and a biopsy of the contents of the core. Preoperative magnetic-resonance imaging was useful for planning which segment of the femoral head should be biopsied. Plain radiographs and tomograms of the hips were also made. On the basis of the plain radiographs, ten hips were determined to have Stage-I findings and six hips, Stage-II ischemic necrosis, according to the system of Ficat and of Arlet and Ficat. Histological study revealed evidence of necrosis in all of the biopsy specimens of bone. We concluded that findings of magnetic resonance imaging that are characteristic of osteonecrosis correlate well with the results of biopsies of bone in patients who have an early stage of ischemic necrosis. Magnetic resonance imaging is a highly sensitive and specific method for both the diagnosis and the location of Stage-I and Stage-II osteonecrosis.

Assessment of radiolucent lines about the glenoid. An in vitro radiographic study.

UNLABELLED: A study was undertaken to investigate the precision of plain radiographs in the assessment of the width of radiolucent lines and to define parameters for more accurate measurement. A metal-backed glenoid component was inserted into fourteen cadaveric scapulae; the component had a radiolucent spacer at the central post to provide a gap with a known width at the component-bone interface. The specimens were mounted in a custom-designed jig, and initial radiographs were made with the glenoid in neutral version; sequential radiographs then were made, at 5-degree intervals, with the glenoid in 0 to 40 degrees of anteversion and retroversion. Four independent observers with various levels of experience measured the width of the radiolucent lines with use of digital microcalipers. Osteometric analysis demonstrated that normal glenoid version ranged from 3 degrees of anteversion to 13 degrees of retroversion; these values were similar to those reported in previous studies. Radiographic analysis showed that accurate measurement of the width of the gap was dependent on the position of the glenoid. The measured widths of the radiolucent lines were significantly smaller than the known width of the gap when retroversion was 10 degrees or more and when anteversion was 15 degrees or more (p < or = 0.05). Radiolucent lines were not consistently observed on radiographs that were made with the glenoid in more than 20 degrees of anteversion and retroversion. An analysis of interobserver error showed close agreement among the measurements made by the different observers when the glenoid was in 0 and 5 degrees of rotation, with decreased agreement when the glenoid was rotated more than 10 degrees from neutral. CLINICAL RELEVANCE: Inaccurate positioning of the patient and anatomical variation in glenoid version may explain the variability in the reported onsets, progressions, and frequencies of radiographic loosening of glenoid components. The findings of the present study also may help to explain the poor association between clinical and radiographic findings reported for patients who have pain at the site of a total shoulder prosthesis. Radiographs made within 10 degrees of neutral should allow accurate assessment of radiolucent lines about the glenoid.

Angiogenesis in healing autogenous flexor-tendon grafts.

On the basis of recent evidence that flexor tendon grafts may heal without the ingrowth of vascular adhesions, eighteen autogenous donor tendons of intrasynovial and extrasynovial origin were transferred to the synovial sheaths in the forepaws of nine dogs, and controlled passive mobilization was instituted early in the postoperative period. The angiogenic responses of the tendon grafts were determined with perfusion studies with India ink followed by cleaing of the tissues with the Spalteholz technique at two, four, and six weeks. A consistent pattern of neovascularization was noted in the donor tendons of extrasynovial origin. Vascular adhesions arising from the flexor digitorum superficialis and the tendon sheath enveloped the tendon grafts by two weeks. By six weeks, the vascularity of the tendon grafts of extrasynovial origin appeared completely integrated with that of the surrounding tissues. Examination of cross sections revealed that the segments of tendon had been completely vascularized by obliquely oriented intratendinous vessels. In contrast, the flexor tendon grafts of intrasynovial origin healed without ingrowth of vascular adhesions. Primary intrinsic neovascularization took place from the proximal and, to a lesser extent, distal sites of the sutures. Examination of cross sections revealed vessels extending through the surface layer of the tendon graft, with small vessels penetrating the interior of the tendons at regular intervals.

Reconstruction of the flexor pulley. The effect of the tension and source of the graft in an in vitro dog model.

Flexor pulleys in the hindpaw digits of twenty-eight adult mixed-breed dogs were reconstructed in order to investigate the influence, on the reconstruction, of the source of the autogenous tissue (intrasynovial compared with extrasynovial tendon) and the tension applied during the repair. The ipsilateral peroneus longus tendon was used to reconstruct the A2 pulley with an around-the-bone technique in twenty-one digits; the graft was sutured at a tension of 0.49, 0.98, and 1.96 newtons in seven digits each. The flexor digitorum profundus tendon of an adjacent digit was used to reconstruct the A2 pulley, at a tension of 0.98 newton, in seven additional digits. The contralateral digits were used as controls for all twenty-eight treated digits. The digits were tested in a custom apparatus designed to measure the frictional force generated between the reconstructed pulley and the tendon beneath it. The frictional force did not differ significantly (p > 0.5) among the three groups repaired with peroneus longus tendon; however, the average value was more than five times that produced in the contralateral, control digits. The average frictional forces created by the flexor digitorum profundus grafts were similar to those in the contralateral, control digits. Reconstruction with the flexor digitorum profundus at a tension of 0.98 newton produced significantly less frictional force (p < 0.05) than that produced by the peroneus longus graft at the same tension. This in vitro model of reconstruction of the A2 pulley demonstrated that tendon from an intrasynovial source (the flexor digitorum profundus) produced less frictional resistance to gliding of the tendon than did tendon from an extrasynovial source (the peroneus longus). This result is consistent with previously published findings that intrasynovial tendons may make better grafts than extrasynovial tendons for the reconstruction of gliding flexor tendons because of decreased friction and better healing qualities. Intrasynovial tendons may also make better grafts for the reconstruction of flexor pulleys.

Carpal tunnel release. A prospective, randomized assessment of open and endoscopic methods.

To define the role of two-portal endoscopic carpal-tunnel release as a method for the treatment of compression of the median nerve at the wrist, a prospective, randomized, multicenter study was performed on 169 hands in 145 patients. Either open or endoscopic carpal-tunnel release was performed in all of the patients who had clinical signs and symptoms consistent with carpal tunnel syndrome, had not responded to or had refused non-operative management, and had had electrodiagnostic studies consistent with carpal tunnel syndrome. Follow-up evaluations were performed at twenty-one, forty-two, and eighty-four days. At the end of the follow-up period, both the open and endoscopic methods had resulted in high levels of achievement of the primary outcomes (relief of pain and paresthesias). The numbness and paresthesias were relieved in eighty (98 per cent) of eighty-two hands in the open-release group compared with seventy-seven (99 per cent) of seventy-eight hands in the endoscopic-release group. This parameter was not recorded for three hands in the open-release group or six hands in the endoscopic-release group. The satisfaction of the patients with the procedure, graded on a scale of 0 to 100 per cent, averaged 84 per cent in the open-release group compared with 89 per cent in the group that had had endoscopic release. We found no significant differences between the two groups with regard to the secondary quantitative-outcome measurements, including two-point discrimination, postoperative interstitial-pressure data for the carpal canal, Semmes-Weinstein monofilament testing, and motor strength. The open technique resulted in more tenderness of the scar than did the endoscopic method. Thirty-two (39 per cent) of eighty-two hands in the open-release group and fifty (64 per cent) of seventy-eight hands in the endoscopic-release group were not tender at eighty-four days. This parameter was not recorded for three hands in the open-release group and six hands in the endoscopic-release group. The open method also resulted in a longer interval until the patient could return to work (median, twenty-eight days, compared with fourteen days for the open-release and endoscopic-release groups). Four complications occurred in the endoscopic carpal-tunnel release group: one partial transection of the superficial palmar arch, one digital-nerve contusion, one ulnar-nerve neuropraxia, and one wound hematoma.(ABSTRACT TRUNCATED AT 400 WORDS)

Autogenous flexor-tendon grafts. A biomechanical and morphological study in dogs.

Intrasynovial and extrasynovial donor autogenous flexor-tendon grafts were placed in the synovial sheaths of the medial and lateral digits of the forepaw in twenty dogs (forty tendons). Postoperatively, the dogs were managed with early, controlled, passive mobilization. Histological and ultrastructural evaluations were carried out at ten days, three weeks, and six weeks, and biomechanical analyses were performed at three and six weeks. The intrasynovial and extrasynovial tendon grafts showed different healing processes histologically. The extrasynovial tendon grafts healed with early ingrowth of peripheral adhesions, which appeared to become larger and more dense over time. These grafts exhibited decreased cellularity and early neovascularization at ten days, and there was evidence of progressive revascularization and cellular repopulation at three and six weeks. In contrast, the intrasynovial tendon grafts demonstrated minimum adhesions, and both cellularity and collagen organization were normal at each time-interval. The intrasynovial grafts had significantly more angular rotation at the proximal interphalangeal joint at three and six weeks than did the extrasynovial grafts (p < 0.05).

Geometric properties and the predicted mechanical behavior of adult human clavicles.

An image processing system was used to examine histomorphometric properties of 15 adult male and female human clavicles. Variations in porosity, cross-sectional area, anatomic and principal moments of inertia were assessed at 2.5-5.0% increments along the length of the clavicles. The clavicle's biomechanical behavior (axial, flexural, and torsional rigidities and the critical force for buckling) was modeled from these data using beam theory. Over threefold variations in porosity and moments of inertia were found along the length of the s-shaped clavicle--the greatest porosity and moments of inertia were located in the variably shaped sternal and acromial thirds of the bone in contrast to the denser and smaller, more circulatory shaped central third of the bone. Clavicle orientation, as indicated by the direction of greatest resistance to bending (maximum principal moment of inertia), was found to rotate from a primarily cranio-caudal orientation at the sternum to a primarily anterior-posterior orientation at the acromion. Based on cross-sectional geometry, section moduli, and estimates of flexural and torsional rigidity, the clavicle was found to be weakest in the central third of its length. These data concur with the fracture location most commonly reported clinically. Analysis of Euler buckling predicted a minimum critical force for buckling during axial loading of approximately two to three body weights for an average adult. Thus, buckling, or a combination of axial loading and bending or torsional loading, must be considered as possible failure mechanisms for this commonly injured bone.

Operative management of displaced femoral head fractures: case-matched comparison of anterior versus posterior approaches for Pipkin I and Pipkin II fractures.

Because of the controversy surrounding the selection of the surgical approach for the operative management of femoral head fractures, we retrospectively reviewed the combined experience with femoral head fractures at two major trauma centers. Forty-three femoral head fractures in 41 patients were identified. Twenty-six of the 43 fractures were Pipkin types I and II, and were managed operatively. Of the 26 patients, 12 with > 2 years of follow-up were managed with posterior surgical approaches and 12 with anterior surgical approaches. These patients were assessed with respect to operative time, estimated blood loss and function, and the radiographs for reduction, avascular necrosis, and heterotopic ossification. There was a significant decrease in operative time, estimated blood loss, and improved visualization and fixation with the anterior approach; however, there was a significant increase in functionally significant heterotopic ossification. The functional results in the two groups were identical; 67% good and excellent in each. There were no cases of avascular necrosis of the femoral head associated with an anterior approach. Because of the greater ease of access to the fracture, the anterior approach is recommended when operative reduction of a displaced Pipkin type I or II is indicated, but newer methods of minimizing heterotopic ossification must be developed.

Intracompartmental pressure measurements in the normal forearm.

In 20 normal subjects, intracompartmental pressure measurements were made at three different sites in the volar forearm: half the distance between the medial epicondyle and ulnar styloid and at points 4 cm proximal and 4 cm distal. The pressure measurements were made using a hand-held digital compartment pressure monitor. The study demonstrated that in the uninjured volar compartment, clinically significant (5 mm Hg) intracompartmental pressure differences exist over distances as little as 4 cm.

Silicone rubber distal ulnar replacement arthroplasty.

We retrospectively reviewed 42 patients who underwent resection of the distal ulna with implantation of a silicone rubber ulnar head prosthesis (45 wrists). Two prostheses were used: the original Swanson prosthesis, and a prosthesis of our own design. Follow-up X-rays showed migration or breakage of 63% of the prostheses. No statistically significant correlation existed between the quality of functional outcome and the integrity of the prostheses. There was no significant difference between pre-operative and post-operative range of motion for the entire group or between patients with broken or intact prostheses. Histological confirmation of silicone synovitis was documented in one patient who required implant removal. We suggest that destabilization and breakage of prostheses result from fatigue failure secondary to the torque generated at the distal radio-ulnar joint during repeated pronation and supination. Use of a silicone rubber ulnar head prosthesis following distal ulna resection is not recommended.

Intrinsic mitogenic potential of canine flexor tendons.

Recent studies have demonstrated an intrinsic neovascular response in intrasynovial healing tendons, introducing the possibility of mitogenic and/or angiogenic capability of intrasynovial tendon. To explore this hypothesis, healing canine flexor tendons were treated with early passive mobilization and the repair sites analysed at three, ten and 17 days. Specimens were mechanically digested and subjected to a standard BALB/c 3T3 mitogenic assay, which measures the capacity of tissue extracts to induce DNA synthesis and cell division in fibroblasts. Results revealed that both control and repaired flexor tendons possessed mitogenic activity, with the greatest activity observed in control specimens. Decreasing activity was noted as the time between repair and analysis increased. These data provide increasing evidence for the flexor tendon's active role in the healing process, and support the concept that mitogenic or growth-promoting factors are associated with flexor tendons and may be released following injury, during the early stages of healing.

The intrinsic and extrinsic ligaments of the wrist. A correlation of collagen typing and histologic appearance.

20 fresh frozen human wrist specimens were dissected. Gross and histological examination and biochemical evaluation were performed on the intrinsic ligaments (scapho-lunate and luno-triquetral) and extrinsic ligaments (radio-scapho-capitate and radio-lunate). All ligaments were observed to have longitudinal collagen bundles. The intrinsic ligaments had large amounts of fibrocartilage near insertions and no elastin, while the extrinsic ligaments had little fibrocartilage and sparse amounts of elastin. The intrinsic ligaments were noted to have significantly more collagen Type 3 (41%) than the extrinsic ligaments (19%). These findings suggest that structural differences between the intrinsic and extrinsic ligaments of the wrist may in part account for the biomechanical observations that the intrinsic ligaments are stronger and elongate further prior to failure than the extrinsic ligaments.

The pathophysiology of carpal tunnel syndrome.

Carpal tunnel syndrome (CTS) is the most frequently encountered peripheral compressive neuropathy. Although the clinical diagnosis and treatment of CTS have been well defined, the pathophysiologic basis still is not understood completely. This article summarizes current thought and research pertinent to the pathophysiology of CTS.

Venomous snake bite: current concepts of treatment.

The optimal treatment of venomous snake-bites remains controversial. Because of the variables involved in treatment, an ideal, prospective clinical trial likely will never be done. The purpose of this article is to review the available treatment methods and outline the treatment methods preferred in our institution for crotalidae envenomation.

Flexor tendon suture methods: a quantitative analysis of suture material within the repair site.

This study compared the cross-sectional area and volume occupied by suture material at the repair site in three common methods of flexor tendon repair. A total of 51 human cadaveric tendons were studied. Zone II flexor digitorum profundus tendon lacerations were created and then repaired using the techniques described by Kessler, Tajima, and Savage. Quantitative cross-sectional area and volumetric measurements of suture material within each repair site were determined using a digital image analysis system. The Tajima repair occupied 27% of the tendon area at the repair site, while the Savage and Kessler repairs occupied 18% and 2%, respectively.

Intercalary flexor tendon grafts. A morphological study of intrasynovial and extrasynovial donor tendons.

Intercalary intrasynovial and extrasynovial flexor tendon graft donors were placed within the synovial sheaths of the medial and lateral forepaw digits of 22 dogs and treated with early controlled passive mobilization. Specimens were studied by light and transmission electron microscopy at 10 and 21 days. Early repair in the extrasynovial tendons occurred by an ingrowth of connective tissue from the digital sheath. Adhesions obliterated the gliding surface and occupied the space between the tendon's gliding surface and surrounding tissues. There was no epitenon response noted in the extrasynovial tendon grafts. While there was considerable new collagen fibril formation within the repair site at the ultrastructural level, there was a lack of longitudinal remodeling. In contrast, the intrasynovial tendon grafts showed early healing, with minimal adhesion formation, by a proliferation and migration of cells from the epitenon. These cells showed greater cellular activity and collagen production at 10 and 21 days compared to cells in extrasynovial tendons at the same intervals. The findings of this study suggest that the use of intrasynovial autogenous tendon graft donors, coupled with early controlled motion, stimulates an intrinsic repair process in both the tendon stump and autogeneous tendon graft. These findings differ significantly from the experimental findings in which extrasynovial, paratenon-covered grafts are used.