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Jeffrey C Christensen

Publications and source records attributed to Jeffrey C Christensen.

16 recordsLinked to original sources
PubMedDate not supplied

ACFAS Universal Foot and Ankle Scoring System: First Metatarsophalangeal Joint and First Ray (module 1).

The American College of Foot and Ankle Surgeons presents the Universal Evaluation Scoring System to evaluate parameters related to foot and ankle surgery. This instrument was developed primarily to allow investigators a means of consistency in clinical assessments. The project was developed in four sections or modules. The first of these modules, First Metatarsophalangeal Joint and First Ray, is presented. This project is unique in that it is the first clinical scoring system of the foot and ankle to become validated by statistical analysis.

Biomechanical Phenomena↗
PubMedDate not supplied

Mosaicplasty of the talus: a joint contact analysis in a cadaver model.

Treating large osteochondral defects of the talar dome is a challenging problem for the foot and ankle surgeon. The purpose of this study was to determine if ankle joint surface mechanics can be restored by repairing large osteochondral defects with multiple osteochondral cylinder grafts. Pressure-sensitive film was used to measure total contact area and mean contact pressure of the ankle joint using a cadaver foot model. Specimens were sequentially tested evaluating the following conditions: 1) intact ankle, 2) with osteochondral defect, and 3) after mosaicplasty. An ovoid chondral defect measuring 8 x 12 mm for each specimen was consistently placed within the center of the contact zone. Multiple osteochondral grafts were harvested from donor tali and placed in the defect. Two graft arrays arranged in either a cluster of four 4 x 10 mm or two 6 x 10 mm plugs were inserted sequentially to fill the defect and were tested separately. Specimens were positioned in a neutral alignment on a custom load frame and axially loaded to 560 N with the pressure transducer in place. The transducers were then digitized and analyzed with an imaging software program. Data for total contact area and mean contact pressures for all conditions of each specimen were collected and statistically analyzed. Results demonstrated that the 6-mm grafts were less than optimal in fully restoring the defect in the contact zone of the talus. There was significant decrease in mean total contact area and increase in contact zone mean pressure compared to the intact condition (p < .05). Whereas, 4-mm plugs nearly restored joint contact area and pressure to normal levels. These findings suggest that focal talar dome defects can be repaired to restore normal ankle contact characteristics via the placement of small, osteochondral cylindrical grafts of talar origin.

Ankle Joint↗
PubMedDate not supplied

Biomechanics of the first ray. Part IV: the effect of selected medial column arthrodeses. A three-dimensional kinematic analysis in a cadaver model.

This study is the fourth in a series of investigations on the biomechanics of the first ray, this part focusing on open kinetic chain range of motion simulating the clinical examination. Segmental sagittal range of motion of the medial column was measured on intact cadaver specimens and compared to various simulated medial column arthrodesis patterns. These arthrodeses included the first metatarsocuneiform, first metatarsocuneiform-intercuneiform, naviculocuneiform, and talonavicular joints. The specimens were mounted to a test apparatus that was comprised of a modified ankle-foot orthosis which held the ankle and rearfoot in fixed neutral position. Additionally, the lesser metatarsus was affixed to the test apparatus while the first ray was left free to be manipulated via a carbon fiber rod attached to a pneumatic actuator. A 24.5-N (5.5-lb) sagittal plane load was applied to the first ray while the specimen was held rigidly in the apparatus. The first ray was manipulated using a repeated measures design. Data were collected for each osseous segment of the medial column using a radiowave tracking system. Kinematic data were collected and statistically analyzed. Results demonstrated in intact specimens that the naviculocuneiform, first metatarsocuneiform, and talonavicular joints contributed an average of 50%, 41%, and 9% of total first ray sagittal plane range of motion, respectively. Furthermore, first ray range of motion was significantly reduced with all of the simulated arthrodeses of the medial column (p < .05). These findings suggest that first ray range of motion when evaluated clinically is a blend of motions of joints comprising the medial column.

Arthrodesis↗
PubMedDate not supplied

Biomechanical consequences of lateral column lengthening of the calcaneus: Part I. Long plantar ligament strain.

Lateral column lengthening of the calcaneus has been a powerful tool used to correct peritalar subluxation in symptomatic flat feet. The mechanical basis and limits for correction with this procedure are not well understood. A flatfoot model was created on 8 fresh-frozen cadaver feet by sectioning the deltoid ligament, talonavicular capsule, and spring ligament. Strain-gauge analysis of the long plantar ligament was performed (on 6 specimens) as the lateral column was sequentially lengthened from 4 to 12 mm in 2-mm increments. Results showed that only the lateral most one-third of the long plantar ligament measured positive strain during this procedure. The medial two-thirds of the long plantar ligament and plantar fascia decreased in tension and became fully lax during lengthening. Maximum tension in the long plantar ligament was measured after placing grafts 6 mm in thickness (P <.05). Larger grafts produced additional strain in the ligament, but were not significant. The authors conclude that grafts >6 mm have no additional corrective capacity without compromising the long plantar ligament. Either larger graft size or loss of the long plantar ligament could compromise the intrinsic stability of the lateral column of the foot. These findings may decrease the incidence of complications with this procedure, specifically lateral column pain, instability, and calcaneocuboid arthrosis.

Biomechanical Phenomena↗
PubMedDate not supplied

Second metatarsophalangeal joint arthrography: a cadaveric correlation study.

Arthrography of the second metatarsophalangeal joint is an important diagnostic tool to evaluate the integrity of the plantar plate and to aid in the decision process for surgical intervention. A variety of filling patterns have been identified with lesser metatarsophalangeal joint arthrography and their significance with soft-tissue pathology remains to be completely understood. The purpose of this cadaveric study was to evaluate dye patterns in a series of arthrograms of the second metatarsophalangeal joint and to correlate them with identifiable anatomic lesions or structural variants. Thirty-nine cadaveric specimens (including 28 matched pairs) underwent second metatarsophalangeal joint arthrography with a colored radiopaque dye. Arthrographic findings were observed and recorded. Specimens exhibiting dye extravasation outside of the capsular constraints of the joint were dissected to discover any soft-tissue abnormalities. Twenty-one percent of specimens exhibited abnormal extravasation of dye outside of the joint capsule. A plantar plate tear was identified in 2 of these specimens. Filling of the first intermetatarsophalangeal bursa occurred in 6 specimens. However, because this finding was identified in 2 matched pairs, an anatomic variance is suggested rather than a pathologic entity. This cadaveric study shows that anatomic variances exist concerning the second metatarsophalangeal capsule and that arthrography should be correlated with the clinical scenario.

Aged↗
PubMedDate not supplied

Biomechanics of the first ray part V: The effect of equinus deformity. A 3-dimensional kinematic study on a cadaver model.

The positional change of the medial column of the foot in closed kinetic chain with variable Achilles tendon tension was investigated in seven fresh frozen cadaver specimens using a 3-dimensional radio wave tracking system. The distal tibia and fibula and the intact ankle and foot and were mounted on a non-metallic loading frame. The frame allowed positioning of the foot to simulate midstance phase of gait while the tibia and fibula were axially loaded to 400 N. To record osseous motion, receiving transducers were attached to the first metatarsal, medial cuneiform, navicular, and talus. Movements of these bones in 3-dimensional space were measured as specimens were axially loaded and midstance motor function was simulated using pneumatic actuators. To simulate a progressive equinus influence, force was applied to the Achilles tendon at tensile loads of 0%, 30%, and 60% of predicted maximum strength during each test trial. Osseous positions and orientations were collected and analyzed in all three cardinal planes utilizing data recorded. As Achilles load increased, the position of the first metatarsal became significantly more inverted ( P < .05). Although not statistically significant, remarkable trends of arch flattening motion were detected in the distal segments of the medial column with varied Achilles load. Increased Achilles load reduced the influence of peroneus longus on the medial column.

Achilles Tendon↗