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Biomedical subjects

R A Berger

Publications and source records attributed to R A Berger.

At least 55 records · Page 3Linked to original sources
PubMed1998

Lunotriquetral ligament properties: a comparison of three anatomic subregions.

The physical attributes of 3 subregions of the lunotriquetral ligament were tested in a computer-controlled multiaxis testing machine using 12 specimens. This allowed measurement of forces, moments, and displacements when ligaments were subjected to distraction, dorsopalmar translation, proximal-distal translation with a 20 N limit, and rotation with a 0.5 Nm limit. After an intact test run, selected subregions were cut randomly. Together with an additional 12 bone-ligament-bone complexes, specimens were tested to failure with servohydraulic load at 5 mm/s. The palmar subregion was thickest (2.3 +/- 0.3 mm), the dorsal and proximal progressively less. Intact rotational displacement was 35 degrees +/- 5.1 degrees, dorsopalmar displacement was 1.6 +/- 0.4 mm and 1.2 +/- 0.5 mm, respectively, proximal-distal displacement was 1.8 +/- 0.5 mm and 1.3 +/- 0.5 mm, respectively, and distractional displacement was 0.3 +/- 0.1 mm. The dorsal subregion provided 62.3% +/- 27.1% of the rotational resistance. The palmar subregion resisted 67.3% +/- 14.1% of palmar translation, while with dorsal translation both regions resisted equally. Rotational displacement increased 15.3 degrees +/- 5.6 degrees after dorsal subregion sectioning. The palmar component failure force was 301 +/- 36 N; the dorsal, 121 +/- 42 N; and the proximal, 64 +/- 14 N.

Biomechanical Phenomena↗
PubMed1998

The lunotriquetral joint: kinematic effects of sequential ligament sectioning, ligament repair, and arthrodesis.

This experiment was conducted to study the effects of sequential sectioning of the ligaments of the lunotriquetral (LT) joint and the effects of simulated repair or arthodesis on kinematics of the wrist joint using an x-ray stereophotogrammetric technique. A 3-dimensional coordinate software program calculated relative motion between bodies as screw axis displacement and rotation about each axis. Sectioning of the proximal and dorsal component of the LT ligament had little effect on carpal kinematics, but sectioning of the proximal and palmar components of the ligament resulted in flexion of both the lunate and triquetrum, producing a volar intercalated segment instability (VISI) pattern. The triquetrum supinated away from the lunate after sectioning of the entire LT ligament. Greater VISI occurred after sectioning the dorsal radiotriquetral and scaphotriquetral ligaments. Progressive destabilization of the LT joint results in increasing kinematic alterations; however, these may not exactly mimic the clinical situation. Moving the wrist through 1,000 cycles increased the instability. Dorsal repair of the LT ligament realigned the lunate and triquetrum, and LT fusion corrected triquetral supination. The latter, however, resulted in overcorrection into extension, which prevented a full wrist extension. The repair used may be insufficient to restore the palmar ligamentous integrity. Lunotriquetral arthodesis was difficult to simulate, providing some insight into the cause of clinical nonunions. Severe VISI is not correctable by repair or arthrodesis and requires further study using reconstructive procedures not discussed here.

Adult↗
PubMed1998

Isolated paralysis of the extensor digitorum communis associated with the posterior (Thompson) approach to the proximal radius.

Seven patients presented with an isolated extensor digitorum communis (EDC) palsy immediately after undergoing surgery in which the posterior (Thompson) approach to the proximal radius was used. All had normal neurologic examination findings documented prior to surgery. In an attempt to localize this lesion, the authors studied the arborization of the terminal motor branches of the posterior interosseous nerve (PIN) at the distal edge of the supinator. A common innervation pattern to the superficial extensor muscles was observed in 29 of 30 cadaveric limbs. In 10 of 10 specimens, when the EDC was subdivided into its individual bellies, a reproducible pattern emerged: the proximal EDC muscles of the middle and ring fingers were supplied primarily by the recurrent nerve branch(es) and the EDC muscles of the index and little fingers, by separate nerve branches. Consistent with our anatomic findings, perioperative stimulation of the recurrent branch in 1 neurologically intact patient resulted in middle and ring finger extension. Electromyography in 8 normal limbs showed that the middle and ring fingers could be activated together without the index and little fingers in all cases. We believe that these patients with isolated EDC nerve palsy may have sustained an iatrogenic injury to EDC motor branches, distal to the supinator rather than to a PIN fascicle near the proximal supinator.

Cadaver↗
PubMed1998

Malrotation causing patellofemoral complications after total knee arthroplasty.

Thirty patients with isolated patellofemoral complications after total knee arthroplasty were compared with 20 patients with well functioning total knee replacements without patellofemoral complications. The epicondylar axis and tibial tubercle were used as references on computed tomography scans to measure quantitatively rotational alignment of the femoral and tibial components. The group with patellofemoral complications had excessive combined (tibial plus femoral) internal component rotation. This excessive combined internal rotation was directly proportional to the severity of the patellofemoral complication. Small amounts of combined internal rotation (1 degree-4 degrees) correlated with lateral tracking and patellar tilting. Moderate combined internal rotation (3 degrees-8 degrees) correlated with patellar subluxation. Large amounts of combined internal rotational (7 degrees-17 degrees) correlated with early patellar dislocation or late patellar prosthesis failure. The control group was in combined external rotation (10 degrees-0 degree). The direct correlation of combined (femoral and tibial) internal component rotation to the severity of the patellofemoral complication suggests that internal component rotation may be the predominant cause of patellofemoral complications in patients with normal axial alignment. The epicondylar axis and tibial tubercle are reproducible landmarks which are visible on computed tomography scans and can be used intraoperatively. Using this computed tomography study can determine wether rotational malalignment is present and thus, whether revision of one or both components may be indicated.

Arthroplasty, Replacement, Knee↗
PubMed1998

Compartment syndrome of the hand and wrist.

High clinical suspicion is of paramount importance in evaluating the hand or wrist for an evolving compartment syndrome. A detailed history coupled with a thorough physical examination form the basis for the diagnosis. The use of techniques to measure compartment pressures forms the objective foundation to assist in formulating the correct treatment plan. The particular technique used to measure the compartments is not critical as long as the information is evaluated in the context of the history and physical examination. No absolute threshold pressure exists over which a fasciotomy is indicated. The need for immediate fasciotomy once the diagnosis is made is clear, however. No one can be faulted for proceeding with a fasciotomy on clinical grounds alone, even when the appearance of findings typically associated with compartment syndrome at surgery (herniating muscle bellies, edema, etc.) are less than convincing. At their worst, the wounds from a fasciotomy present a cosmetic challenge. Great fault can be assigned, however, to the clinician who chooses to ignore an evolving compartment syndrome that unnecessarily places the patient at risk of permanent disability. Here, the cosmetic benefit of avoiding the fasciotomy is overwhelmed by the often-devastating dysfunction created by ischemic damage to the contents of the affected compartments. Once the damage is done, it is permanent. A thorough understanding of the pertinent anatomy is critical to safe, efficacious treatment. Handled promptly and judiciously, compartment syndrome of the hand and wrist can be managed effectively, decreasing the morbidity associated with this potentially devastating and debilitating process.

Compartment Syndromes↗
PubMed1997

Normal kinematics of carpal bones: a three-dimensional analysis of carpal bone motion relative to the radius.

Normal carpal kinematics were studied in 22 cadaver specimens using a biplanar radiography method. The kinematics of the trapezium, capitate, hamate, scaphoid, lunate, and triquetrum were determined during wrist motion in sagittal and coronal planes. The results were expressed using the concept of the screw displacement axis and converted to describe the magnitude of rotation about and translation along three axes (X-axis: pronation-supination axis, Y-axis: flexion-extension axis, and Z-axis: radial-ulnar deviation axis) commonly used for the wrist. The orientation of these axes is expressed relative to the radius. Within the proximal carpal row, considerable differences of carpal behavior around the Y-axis were observed during sagittal plane motion of the wrist. The scaphoid exhibited the greatest magnitude of rotation, and the lunate the least. The magnitude of rotation of the carpal bones around the X-axis during sagittal plane motion of the wrist was small. The proximal carpal bones exhibited some ulnar deviation in 60 degrees of wrist flexion. During coronal plane motion of the wrist, the magnitude of radial-ulnar deviation of the distal carpal bones was mutually similar and generally of a greater magnitude than that of the proximal carpal bones. The proximal carpal bones experienced some flexion during radial deviation of the wrist and extension during ulnar deviation of the wrist. Translation was generally minimal in all carpal bones throughout wrist motion. This study reports results from the largest cadaver wrist kinematics study completed to date. The accuracy of the current method was improved when compared to previous studies. A sufficient number of specimens to allow statistical comparison was used and minimal interspecimen variability was noted. This study enabled a precise description of quantitative analyses of normal carpal kinematics relative to the radius.

Adult↗
PubMed1997

A technique for arthroscopic evaluation of the first carpometacarpal joint.

Arthroscopy of the first carpometacarpal joint has been developed as a reliable surgical procedure offering an opportunity for direct evaluation of the joint's intra-articular status, with minimal morbidity to the joint capsule. The procedure uses a 1.9-mm short barrel arthroscope with standard supportive electronic equipment. After adequate anesthesia is established, approximately 5 lb. of longitudinal traction is applied to the thumb. Arthroscopic portals are located on the radial side of the abductor pollicis longus tendon (1-R portal) and the ulnar side of the extensor pollicis brevis tendon (1-U portal). Care must be exercised in establishing these portals so that injury to the radial artery and branches of the superficial radial nerve can be avoided.

Arthroscopes↗
PubMed1997

Effect of a centralizing device on cement mantle deficiencies and initial prosthetic alignment in total hip arthroplasty.

Sixty consecutive patients undergoing a primary hybrid total hip arthroplasty were randomized to receive a femoral component either with or without a distal centralizing device. The group with a centralizer had significantly fewer patients with cement mantle deficiencies (excessively thin areas of cement) than the group without a centralizer (P < .001). Furthermore, the centralizer group was, on average, in a neutral alignment, whereas the group without a centralizer was in a varus alignment (P < .001). It was concluded that the distal centralizing device significantly decreases the incidence of cement mantle deficiences and reproducibly aids in achieving a more neutral prosthetic alignment.

Bone Cements↗
PubMed1997

Intercarpal kinematics during wrist motion.

Twenty-two fresh cadaver specimens were analyzed using a three-dimensional biplanar roentgenographic kinematic technique to quantitate intercarpal motion. The large number of specimens provided substantial power to dramatically optimize the statistical significance of the measurements. It was confirmed that the bones of the distal carpal row behave as a single, functional unit with little intercarpal motion and are directly linked to movement of the third metacarpal. The scaphoid, lunate, and triquetrum exhibit significant "out of plane" motion, noted mainly in relation to the distal row bones. Measurable differences in the kinematics of the proximal row bones, relative to each other, were repeatedly defined.

Adult↗
PubMed1997

Primary cementless acetabular reconstruction in patients younger than 50 years old. 7- to 11-year results.

The efficacy of primary cementless acetabular reconstruction in patients younger than 50 years of age was analyzed in 79 consecutive cementless, hemispheric, porous coated acetabular reconstructions (Harris-Galante-I). The average age was 37 years at surgery (range, 20-49 years). The average followup was 106 months (range, 78-126 months). No acetabular reconstructions were revised for aseptic loosening. Two stable acetabular reconstructions were revised during femoral revision. Two excessively worn polyethylene liners were exchanged and one acetabular osteolytic area was debrided and grafted; these procedures retained the metal shell. At final followup, all 72 acetabular reconstructions were radiographically stable. Acetabular osteolysis occurred in five cases (7.4%), from 84 to 104 months. Acetabular or femoral osteolysis occurred in patients with increased polyethylene wear. Polyethylene wear was inversely related to the patient's age. Using revision and loosening, the Kaplan-Meier 10 year survival of the acetabular reconstruction was 98.8% (95% confidence interval, 96.6%-100.%). The intermediate results of cementless, hemispheric, porous coated acetabular reconstruction in younger patients was excellent with no radiographic loosening. At 7- to 11-year followup, osteolysis was the most common problem and increased in frequency and extent with continued in vivo duration.

Adult↗
PubMed1996

Rotational laxity and stiffness of the radiocarpal joint.

OBJECTIVE: To investigate the constraint and potential mechanism of torque transmission across the wrist joint. DESIGN: In vitro experiment using human cadaveric specimens. BACKGROUND: Transmission of torque from the forearm to the hand requires rotational stability at the wrist. Better appriciation of the constraints would have applicability to several clinical problems where the stability is compromised. METHODS: Thirteen fresh-frozen cadaveric specimens were used in this experiment to investigate the rotational laxity and stiffness of the radiocarpal joint in unloaded and axially loaded (100 N) conditions, and three forearm orientations in a neutral, pronation (60 degrees ), or supination (60 degrees ) position. RESULTS: In pronation or supination, there was no difference between loaded and unloaded conditions in primary or total laxity at a maximum torque of 2.3 Nm. Unloaded specimens showed a mean total rotational laxity of 42.1 degrees. Supination or pronation of the forearm caused a decrease in laxity with respect to neutral forearm rotation (35 degrees and 41.6 degrees versus 49.6 degrees respectively). The primary rotational laxity accounted for half of the total laxity. With axial compression, total rotational laxity did not change, but primary laxity dropped to 50% of its unloaded value. The primary stiffness was very low -- approximately 11% of the secondary stiffness. CONCLUSION: The ligamentous structures and the joint articulation restricted excessive axial rotation of the wrist. However, a laxity of approximately 20 degrees was identified for normal wrists. RELEVANCE: This study demonstrated that the primary axial rotational laxity of the radiocarpal joint was approximately 20 degrees. In the mathematical model and implant design, muscular balance of the joint within such laxity should be considered.

Journal Article↗
PubMed1996

The capitohamate ligaments. A comparison of biomechanical properties.

The physical attributes of the three capitohamate interosseous ligaments were tested in a computer-controlled multi-axis testing machine using 12 human cadaver specimens. After an intact test run, selected ligaments were cut in random sequence and the test repeated. The remaining ligaments were tested to failure with servohydrolic stress at 5 mm/second. In the intact joint complex, the average dorsopalmar rotational displacement was approximately 9 degrees in each direction. Under the load limit, the dorsopalmar translational displacement averaged 0.9 mm and 0.5 mm respectively, proximal-distal translational displacement averaged 0.8 mm and 0.4 mm respectively, and distractional displacement averaged 0.3 mm. Based on the sequential sectioning it was found that the dorsal ligament provided 76% (SD 14) of the rotational resistance with palmar rotation of the capitate and 44% (SD 19) of translational constraint with palmar translation of the capitate. The deep ligament provided 51% (SD 15) of the rotational resistance with dorsal rotation of the capitate and 63% (SD 24) of translational resistance with dorsal translation of the capitate. With proximal-distal translation, the dorsal ligament was the most important constraint in each direction. In resisting distraction, each of the three ligaments was equally effective. Failure testing showed the deep ligament was strongest at 289 N, followed by the palmar at 171 N and the dorsal at 133 N.

Adult↗
PubMed1996

The gross and histologic anatomy of the scapholunate interosseous ligament.

The scapholunate interosseous ligament, which connects the carpal scaphoid and lunate bones, was evaluated by gross dissection and serial histologic sections in transverse, sagittal, and coronal planes in 21 fresh and 16 fixed adult cadaver wrists. The scapholunate interosseous ligament is consistently divisible into three anatomic regions: dorsal, proximal, and palmar. The dorsal region is thick and composed of short, transversely oriented collagen fibers. The proximal region is principally composed of fibrocartilage, with a few superficial, longitudinally oriented collagen fibers. The proximal region may extend distally a few millimeters into the scapholunate joint space, thus resembling a knee meniscus. The radioscapholunate ligament separates the proximal and palmar regions of the scapholunate interosseous ligament, often extending distally to cover the dorsal surface of the palmar region of the scapholunate interosseous ligament. The palmar region is thin and composed of obliquely oriented collagen fascicles, just dorsal to and separate from the long radiolunate ligament.

Adult↗