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Biomedical subjects

M T Dahl

Publications and source records attributed to M T Dahl.

4 recordsLinked to original sources

Limb length discrepancy.

The surgical management of LLD has gradually evolved from a time when patients were bedridden in traction for prolong periods of time to the point at which much of the treatment time is spent in mobility. Improved surgical techniques, such as percutaneous epiphysiodesis and distraction osteogenesis, have contributed greatly to the success of surgery for LLD. Factors affecting outcome and patient satisfaction must be weighed carefully before selecting treatment for LLD.

Extremities

Complications of limb lengthening. A learning curve.

Major complication rates during limb lengthening were plotted in a consecutive series to produce a learning curve. All unwanted events during and after treatment were considered complications, and graded as minor, serious, and severe. All serious and severe complications were considered major. A novel system was used to classify the preoperative severity of each deformity. One-hundred ten patients had 140 bone segments lengthened between 2.2 cm and 10.5 cm, with a mean of 4.4 cm. Three methods were used in lengthening: the Wagner method in 22 patients, the DeBastiani method in 34 patients, and the Ilizarov method in 84 patients. Ninety-eight complications categorized as serious or severe occurred, for a total major complication rate of 72%. The percentage of major complications began to drop after 30 lengthenings to a current rate of 25%. Major complications were frequent in patients with more severe deformities, particularly in those whose cases occurred early in the series. Bone healing complications were high (72%) in the Wagner segments but were also high (80%) in the first ten patients treated with the DeBastiani technique. The first ten Ilizarov patients, who were treated later in the series, had a 40% rate of bone-healing complications. The current rate of major complications is 13% for those patients treated with DeBastiani's method and 33% for those patients treated with Ilizarov's method. This difference in complication rates appears to relate to the severity of the deformity, rather than the device used. There was a significant decrease in complications as experience was gained. Directed formal study and surgical instruction should help diminish these complications.

Adolescent

The gradual correction of forearm deformities in multiple hereditary exostoses.

Careful preoperative planning, fixator selection and design, surgical technique, and sustained follow-up care are essential for successful gradual correction of pediatric forearm deformities. The sequence of planning gradual deformity correction can be created by establishing a problem list and using this as the basis for design of the gradual correction. Viewing limb length and deformity correction as a "process," rather than a procedure, is of value. Using a hybrid fixation formula that combines half pins with wires can minimize the potential for neurovascular injury. The combination of radial osteotomy, excision of osteochondromas, and gradual ulnar lengthening by distraction osteogenesis improves forearm appearance and function in most patients with multiple hereditary exostoses.

Biomechanical Phenomena

Lower extremity lengthening by Wagner's method and by callus distraction.

Fifty-three patients underwent 64 lengthenings of the femur or tibia by the Wagner technique or by the callus distraction method. Thirty-six femoral and 28 tibial segments were lengthened. Simultaneous lengthening of the femur and tibia was performed in seven limbs. Three segments underwent repeat lengthenings. The average length gained by the Wagner method was 5.1 cm in the femur and 5.4 cm in the tibia. Length gains by callus distraction were 4.9 cm in the femur and 4.5 cm in the tibia. Complication rates were fewer and less severe with callus distraction. The number of operations, days of hospitalization, and length of total treatment were less in patients operated on with the callus distraction method than in those who underwent the Wagner technique.

Adolescent