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Biomedical subjects

L C Schon

Publications and source records attributed to L C Schon.

At least 19 recordsLinked to original sources
PubMed2002

[Airlimb. Initial experiences with a new immediate early management prosthesis with individually adjustable air chambers].

Amputations of the lower extremity are still a common problem in diabetic feet and peripheral vasculopathies. The presented paper introduces a new device for an easier and faster mobilization of below-the-knee amputees. It is based on a new modular prostheses with individual inflatable air bladders. The compliance rate is higher with this device and it could be used from the day of surgery until the definitive prostheses is made. A biomechanical cadaver study with the prostheses will also be presented.

Adult↗
PubMed2001

Surgical treatment of chronic lower extremity neuropathic pain.

The current authors retrospectively reviewed 147 lower extremity peripheral nerve procedures in 114 patients (average age, 42 years) with chronic lower extremity neuropathic pain to determine whether surgical treatment based on an empirically derived algorithm could reduce pain and improve function. This algorithm assigns crush, stretch, and chronic transection injuries to treatment with transection and containment. Peripheral nerve stimulation was used in conjunction with transection and containment for patients with more chronic presentations for whom previous transections had been unsuccessful. Patients with adhesive neuralgia underwent revision neurolysis with vein wrapping. Patients with repetitive nerve trauma (overuse) underwent primary or revision neurolysis. Duration of symptoms averaged 37 months, and mechanisms of nerve injury included chronic transection, crush, adhesive neuralgia, stretch, repetitive trauma, and idiopathic etiology. Time to followup averaged 38 months. Pain and dysfunction were ranked from 0 points (no pain or dysfunction) to 10 points (pain prompting request for amputation or functional deficit warranting wheelchair use); preoperative and followup work status were documented. Average pain and dysfunction scores improved: 8.8 to 5.6 points and 7.6 to 5.0 points, respectively. Of the 114 patients, 52 (46%) patients improved their work status, including 35 of 87 (40%) involved in workers' compensation. There were no statistically significant differences in outcome based on mechanism of nerve injury or type of procedure. The consistent average improvement suggests this algorithm assigns the appropriate procedure to a given mechanism of injury.

Adolescent↗
PubMed2001

Complex salvage procedures for severe lower extremity nerve pain.

From 1995 to 1999, the senior author did revision nerve release and vein wrapping (58 limbs in 58 patients) or peripheral nerve stimulation (62 limbs in 62 patients) to relieve intractable lower extremity nerve pain. Vein wrapping was done if the patient had temporary relief after a previous nerve release, if there was evidence of scarring around the nerve, and if nerve pain was triggered by mechanical stimulation. Peripheral nerve stimulation was done when previous nerve operations provided no relief or if the nerve pain was more constant and spontaneous without mechanical provocation. The duration of symptoms preoperatively averaged 52 months, and the number of previous peripheral neurosurgical interventions averaged 2.5. Postoperatively, the average pain improvement was rated as 60% for the patients who had vein wrapping and 41% for the patients who had peripheral nerve stimulation. Of the patients who had vein wrapping, 53% were satisfied, 14% were somewhat satisfied, and 33% were dissatisfied. Of the patients who had peripheral nerve stimulation, 61% were satisfied, 21% were somewhat satisfied, and 18% were dissatisfied. Most patients (78%) stated they would undergo the procedures again.

Adult↗
PubMed2001

Biomechanical evaluation of the ability of casts and braces to immobilize the ankle and hindfoot.

We evaluated the ability of seven devices to immobilize a prosthetic ankle-foot complex against plantarflexion, dorsiflexion, inversion, and eversion forces: two casts (plaster of Paris and Fiberglas) and five removable braces (molded ankle/foot orthosis, composite boot brace, pneumatic boot walker, nonarticulating fracture boot, and ankle stirrup). Each device was applied to a prosthetic ankle-foot complex and evaluated on a test frame for resistance to sagittal motion and coronal torque. Results showed that casts offered significantly (P < or = 0.05) more resistance to motion in all directions tested than did the braces. The resistance offered by the devices tested depends on the conformity of the device to the shape of the foot in that plane and the material properties of the device. Braces offer the advantage of being easily removed and reapplied. Different braces offer specific advantages and disadvantages in different planes tested, and immobilization selection should be individualized based on this information.

Ankle↗
PubMed2001

Subtalar distraction bone block arthrodesis.

This retrospective study analyses the results of subtalar bone block distraction arthrodesis used in the treatment of late complications of calcaneal fractures, acute severely comminuted fractures, nonunion (and malunion) of attempted subtalar arthrodeses, avascular necrosis of the talus, and club-foot deformity. Of 39 patients (41 feet) who had this procedure, 35 (37 feet) returned for follow-up after a mean of 70 months (26 to 140). There were 24 men (25 feet) and 11 women (12 feet) with a mean age of 41 years (16 to 63). Each completed a standardised questionnaire, based on the hindfoot-scoring system of the American Orthopaedic Foot and Ankle Society and were reviewed both clinically and radiologically. Of the 37 operations, 32 (87%) achieved union. The mean hindfoot score (maximum of 94 points) increased from 21.1 points (8 to 46) preoperatively to 68.9 (14 to 82) at the final follow-up. The mean talocalcaneal and calcaneal pitch angles were 20.5 degrees and 4.9 degrees before operation, 25.9 degrees and 8.3 degrees immediately after, and 24.6 degrees and 7.7 degrees at the final follow-up, respectively. The mean talar declination angle improved from 6.5 degrees (-10 to 22) before operation to 24.8 degrees (14 to 32) at the final follow-up. The mean talocalcaneal height increased from 68.7 mm before operation to 74.5 mm immediately after and 73.5 mm at the final follow-up. Of the 37 arthrodeses available for review, 32 were successful; 29 patients (30 arthrodeses) were satisfied with the procedure. Minimal loss of hindfoot alignment occurred when comparing radiographs taken immediately after operation and at final follow-up.

Adolescent↗
PubMed2000

Six first metatarsal shaft osteotomies: mechanical and immobilization comparisons.

Because malunion (usually with dorsal elevation of the first metatarsal) has been reported after the treatment of severe hallux valgus deformities by proximal osteotomies, the current study was designed to compare the sagittal stability of six different metatarsal shaft osteotomies: the proximal crescentic, proximal chevron, Mau, Scarf, Ludloff, and biplanar closing wedge osteotomies. A plate was used in the biplanar closing wedge osteotomy; all others used screws for fixation. Ten fresh-frozen, human anatomic lower extremity specimens were used for each osteotomy. Failure loads were measured as units of force (newtons) and converted to pressure (kilopascals). Then the F-Scan system, which uses a thin insole to measure plantar pressure, was used to evaluate the pressure under the first metatarsal of seven volunteers using four types of shoes. According to the results, in patients with normal bone stock who are compliant, any of the four shoe types tested may be used after a Ludloff, Scarf, biplanar wedge (plantar screw fixation), or Mau osteotomy, but the wedge-based shoe should be used after a proximal crescentic or chevron osteotomy or for patients with severe osteopenic bone.

Biomechanical Phenomena↗
PubMed2000

Result of arthrodesis of the hallux metatarsophalangeal joint using bone graft for restoration of length.

We treated 24 patients (18 women, six men; average age, 46.4 years; (range, 28 to 66 years) with fusion of the hallux metatarsophalangeal (MTP) joint using bone graft for the restoration of the length of the first ray. This procedure was performed after bone loss subsequent to previous surgeries for the correction of hallux valgus and hallux rigidus with: silastic arthroplasty (11), bunionectomy and distal metatarsal osteotomy (six), Keller resection arthroplasty (five), and total joint replacement (two). The indication for performing the arthrodesis with bone graft was a short first metatarsal, and associated metatarsalgia of the lesser metatarsals in addition to a painful MTP joint with or without deformity. This bone loss was associated with avascular necrosis of the first metatarsal (nine patients) and with osteomyelitis (seven patients). Of the 24 patients, 14 underwent additional concurrent surgery for correction of hammer toes (10), excision of a Morton's neuroma (two), and lesser metatarsal osteotomy (two). All patients were examined clinically and radiographically at a mean interval of 62.7 months after surgery (range, 26 to 108 months). The patients were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) hallux and MTP 100-point outcome scale. Arthrodesis occurred in 19/24 patients (79.1%) at a mean of 13.3 weeks (range, 11 to 16 weeks), and the first ray was lengthened by a mean of 13 mm (range, 0 to 29 mm). Of the five nonunions, two were asymptomatic, and three were subsequently revised successfully, with arthrodesis occurring at a mean of 10.7 weeks. Complications included one deep infection requiring intravenous antibiotics for treatment of osteomyelitis and two minor superficial wound infections. The mean AOFAS score improved from 39 points (range, 22 to 60 points) to 79 points (range, 64 to 90 points). All patients were satisfied with the final outcome of treatment and stated that they would undergo the surgical procedure again. We concluded that arthrodesis of the hallux MTP joint with bone graft to restore bone loss and length of the first ray may be a worthwhile procedure despite the technical difficulty and the high rate of nonunion.

Adult↗
PubMed2000

Peripheral nerve vein wrapping for intractable lower extremity pain.

HYPOTHESIS/PURPOSE: The purpose of this study was to determine the effectiveness of lower extremity peripheral nerve vein wrapping procedures in the management of patients with intractable lower extremity pain. The hypothesis was that nerve insulation through vein wrapping is effective in treating symptoms related to adhesive neuralgia, but not those secondary to intraneural damage. METHODS: We retrospectively reviewed 25 consecutive patients whose intractable chronic lower extremity peripheral neuralgia had been treated with revision neurolysis and vein wrapping. The 14 women and 11 men had an average age of 39 years (range, 21 to 53 years). Vein wrapping was performed using a saphenous vein autograft in 19 patients and a fetal umbilical vein in six patients. The average length of follow-up after vein wrapping was 24 months (range, 12 to 63 months). Assessment of pain and dysfunction was on a scale of 0 (no pain/dysfunction) to 10 (severe enough to prompt request for amputation and required use of a wheelchair). RESULTS: Pain scores improved from a preoperative average of 8.7 points (range, 6 to 10 points) to a postoperative average of 4.6 points (range, 0 to 10 points); dysfunction improved from a preoperative average of 7.3 points (range, 3 to 10 points) to a postoperative average of 4.4 points (range, 0 to 9 points). Although 17/25 patients were satisfied with the procedure, only 14/25 stated they would undergo the surgery again. All eight patients who exhibited no improvement had preoperative and intraoperative evidence of an idiopathic etiology and/or intraneural damage. Preoperatively, 18/25 patients could not work; postoperatively, that number improved to 8/25. CONCLUSIONS: Vein wrapping of lower extremity peripheral nerves is most effective in relieving symptoms related to adhesive neuralgia and less beneficial in the presence of intraneural damage. Although symptoms are rarely relieved completely, vein wrapping typically results in a substantial improvement in symptoms related to scar entrapment of peripheral nerves.

Adult↗
PubMed2000

Clinical outcome after primary triple arthrodesis.

BACKGROUND: To analyze the effects of multiple preoperative, intraoperative, and postoperative factors on the intermediate results of triple arthrodesis, we focused on preoperative deformity, preoperative diagnosis, degree of clinical and radiographic correction, and arthritis of the ankle. METHODS: Between 1987 and 1995, 160 patients were managed with a total of 183 triple arthrodeses. Patients who had an infection or neuroarthropathy or who were managed with a revision arthrodesis were excluded from our study. Of the 160 patients, 111 (132 feet) who had been followed for a minimum of two years formed our study group. Each patient had an arthrodesis with rigid screw fixation and realignment of the joint surfaces without resection of wedges. The average duration of follow-up was 5.7 years (range, 2.0 to 10.8 years). RESULTS: As seen radiographically, arthritis of the ankle was significantly more severe postoperatively than preoperatively (p<0.01), although patient satisfaction was not associated with the presence of arthritis. On a scale (not a visual analog) of 0 (not satisfied) to 10 (completely satisfied), overall satisfaction averaged 8.3 points (range, 0 to 10 points). The postoperative modified ankle-hindfoot score of the American Orthopaedic Foot and Ankle Society averaged 60.7 points (range, 0 to 94 points). There was a significant association (p = 0.001) between satisfaction of the patient and postoperative alignment. Ten patients had a total of eleven complications: four superficial wound problems, three nonunions, one case of superficial peroneal neuritis, one case of Charcot-like neuroarthropathy of the foot (in a patient in whom diabetes developed during the follow-up period), one rupture of the Achilles tendon, and one case of peroneal tenosynovitis. Of the 111 patients, 101 (91 percent) stated that they would have the procedure again under similar circumstances, and this response was independent of the preoperative diagnostic or deformity group. CONCLUSIONS: Triple arthrodesis for the treatment of various deformities and etiologies is effective in relieving pain and improving functional deficits. Although a high prevalence of subsequent arthritis of the ankle was noted clinically and radiographically, we could detect no association between satisfaction of the patient and arthritis.

Adolescent↗
PubMed2000

Isolated subtalar arthrodesis.

BACKGROUND: The purposes of this retrospective study were to review the results of isolated subtalar arthrodesis in adults and to identify factors influencing the union rate. The hypotheses were that (1) the overall outcome is acceptable but is not as favorable as previously reported, (2) complication rates, especially the nonunion rate, are higher than previously reported, and (3) factors contributing to a less favorable union rate can be identified. METHODS: Between January 1988 and July 1995, 184 consecutive isolated subtalar arthrodeses were performed in 174 adults (115 men and fifty-nine women) whose average age was forty-three years (range, eighteen to seventy-nine years). Eighty patients (46 percent) were smokers. The indications for the procedure included posttraumatic arthritis after a fracture of the calcaneus (109 feet), a fracture of the talus (thirteen feet), or a subtalar dislocation (thirteen feet); primary subtalar arthritis (thirteen feet); failure of a previous subtalar arthrodesis (twenty-eight feet); and residual congenital deformity (eight feet). Rigid internal fixation with one or two screws was used for all feet. Bone graft was used in 145 feet; the types of graft material included cancellous autograft (ninety-four feet), structural autograft (twenty-nine feet), cancellous allograft (seventeen feet), and structural allograft (five feet). Bone graft was not used in the remaining thirty-nine feet. RESULTS: Clinical and radiographic follow-up examinations were performed for 148 (80 percent) of the 184 feet at an average of fifty-one months (range, twenty-four to 130 months) postoperatively. The average ankle-hindfoot score according to the modified scale of the American Orthopaedic Foot and Ankle Society (maximum possible score, 94 points) improved from 24 points preoperatively to 70 points at follow-up. Thirty feet had clinical evidence of nonunion. The union rate was 84 percent (154 of 184) overall, 86 percent (134 of 156) after primary arthrodesis, and 71 percent (twenty of twenty-eight) after revision arthrodesis. The union rate was 92 percent (ninety-three of 101 feet) for nonsmokers and 73 percent (sixty-one of eighty-three feet) for smokers (p < 0.05). Intraoperative inspection revealed that 42 percent (seventy-eight) of the 184 feet had evidence of more than two millimeters of avascular bone at the subtalar joint; all thirty nonunions occurred in this group (p < 0.05). A nonunion occurred in three of the five feet that had been treated with structural allograft and in two of the six feet in which the subtalar arthrodesis had been performed adjacent to the site of a previous ankle arthrodesis. After elimination of the subgroups of feet in patients who smoked, those that had had a failure of a previous subtalar arthrodesis, those that had been treated with a structural graft, and those that had had the subtalar arthrodesis adjacent to the site of a previous ankle arthrodesis, the union rate improved to 96 percent (seventy-three of seventy-six). Complications other than nonunion included prominent hardware requiring screw removal (thirty-six of 184 feet; 20 percent), lateral impingement (fifteen of 148 feet; 10 percent), symptomatic valgus malalignment (five of 148 feet; 3 percent), symptomatic varus malalignment (four of 148 feet; 3 percent), and infection (five of 184 feet; 3 percent). CONCLUSIONS: To the best of our knowledge, the present study includes the largest reported series of isolated subtalar arthrodeses in adults. Our results suggest that the outcome following isolated subtalar arthrodesis is not as favorable as has been reported in previous studies. The rate of union was significantly diminished by smoking, the presence of more than two millimeters of avascular bone at the arthrodesis site, and the failure of a previous subtalar arthrodesis (p < 0.05 for all). Other factors that probably affect the union rate include the use of structural allograft and performance of the arthrodesis adjac

Adult↗
PubMed1999

Biomechanical evaluation of two different screw positions for fusion of the calcaneocuboid joint.

In triple arthrodesis performed for severe deformity and neuroarthropathy in poorly compliant patients with osteoporotic bone, fixation of the arthrodesis is critical. We biomechanically tested an alternative means of stabilization for calcaneocuboid fusions. In seven matched pairs of fresh-frozen cadaver feet, we removed the soft tissue from around the calcaneocuboid joint, except for the capsule, and we did not resect the articular cartilage. One joint of each pair was fixed with an oblique standard screw, and the contralateral joint was stabilized with an axial screw placed perpendicularly to the joint surface. Testing on an MTS Mini Bionix Test Frame (MTS Systems Corp., Eden Prairie, MN) demonstrated that the axial screw provided significantly higher initial stiffness and maximum load to failure. We concluded that an axial screw provided better fixation of the calcaneocuboid joint.

Arthrodesis↗
PubMed1998

Hallux metatarsophalangeal arthritis.

Arthritis of the hallux metatarsophalangeal joint is a common disorder that affects shoewear, ambulation, and other activities of daily living. Etiologies include degenerative arthritis (hallux rigidus), crystal induced arthropathy (gout, pseudogout), rheumatoid arthritis, the seronegative spondyloathropathies, posttraumatic degeneration, and advanced hallux valgus. Accurate diagnosis and selection of the appropriate intervention depends on recognition of pertinent clinical and radiographic features. This study presents a synopsis of the senior author's (LCS) experience with 439 surgically treated patients with hallux metatarsophalangeal arthritis, focusing on origin and treatment.

Arthritis↗
PubMed1998

Charcot neuroarthropathy of the foot and ankle.

The goal of this study was to characterize Charcot neuroarthropathy of the foot and ankle by specific sites of involvement (ankle, hindfoot, midfoot, and forefoot), modes of presentation, methods of management, and outcome. A summary of treatment and results for 50 ankles, 22 hindfeet, 131 midfeet, and 18 forefeet is presented. Nondisplaced neuropathic ankle fractures typically healed uneventfully with casting and bracing. For displaced ankle fractures, closed reduction and casting generally resulted in loss of reduction and progressive deterioration; better results were obtained with open reduction and internal fixation, using supplemental Kirschner wires and screws. Ankles with Charcot neuroarthropathy and preexisting arthritis typically required arthrodesis. Of the ankles with neuropathic avascular talar necrosis, approximately 1/3 did well with nonoperative intervention and 2/3 required surgery. Chronic, unstable, malaligned Charcot ankles often required arthrodesis. Neuropathic calcaneal fractures were managed successfully nonoperatively. For feet with transverse tarsal joint involvement (Schon Type IV), management was more complex. Nonoperative treatment was successful for less than 1/2. Two thirds of the feet with midtarsus involvement (Schon Types I, II, and III) were managed successfully nonoperatively; 1/3 required surgery for recurrent ulceration, instability, or osteomyelitis. Half of the feet with forefoot neuroarthropathy required surgery for malalignment, ulceration, and/or difficulty with shoewear or braces. This review has established patterns of Charcot involvement of the foot and ankle with corresponding methods of treatment and subsequent responses. From this extensive clinical experience with 221 neuropathic fractures or Charcot joints, recommendations were derived to assist in selecting appropriate management options.

Ankle Joint↗
PubMed1998

Posttraumatic posterior tibialis tendon insertional elongation with functional incompetency: a case report.

We present a case report and literature review of distal intrasubstance rupture of the posterior tibial tendon with progressive pes planovalgus secondary to tendon incompetence. Three months after a severe ankle sprain, a 25-year-old basketball player presented with ankle weakness and pain. Treatment by advancement of the posterior tibial tendon to the navicular and medial displacement osteotomy of the calcaneal tuberosity restored alignment, strength, and full function.

Adult↗
PubMed1998

Mechanical comparison of biplanar proximal closing wedge osteotomy with plantar plate fixation versus crescentic osteotomy with screw fixation for the correction of metatarsus primus varus.

Proximal crescentic metatarsal osteotomy is a clinically successful technique for correcting metatarsus primus varus in hallux valgus surgery. However, there have been instances of dorsal elevation of the metatarsal head with this technique. Mechanical testing on 10 matched pairs of cadaver feet was performed to evaluate a new technique combining a biplanar closing wedge osteotomy and plantar plate fixation versus crescentic metatarsal osteotomy. The specimens were tested in cantilever-bending mode on an MTS Mini Bionix test frame. The mean load-to-failure values were 127.2 +/- 81.9 N (SD) for biplanar osteotomy with plate fixation and 44.9 +/- 43.3 N for crescentic osteotomy (P = 0.019); the mean stiffness values at the initial portion of the load-deflection curve were 83.11 +/- 73.76 N/mm and 31.95 +/- 43.00 N/mm, respectively (P = 0.012). The biplanar wedge osteotomy with plantar plate fixation demonstrated significantly stronger fixation than the crescentic osteotomy, with higher mean load-to-failure and stiffness values. This newly described technique may provide an acceptable alternative for patients at risk for dorsal elevation of the metatarsal, particularly those who are noncompliant or have osteopenia. Clinical study will determine whether this new technique offers satisfactory long-term results.

Biomechanical Phenomena↗
PubMed1998

A new modified technique for harvest of calcaneal bone grafts in surgery on the foot and ankle.

Reported sites for retrieval of cancellous bone for grafts include the iliac crest, greater trochanter, proximal tibia, and distal tibia. A new lateral technique for retrieval of cancellous bone from the calcaneus is evaluated through anatomic review, quantitative analysis, and retrospective clinical assessment. Of 22 patients managed with this technique over a 2-year period, 17 returned for an evaluation by questionnaire, physical examination, and radiographic follow-up at an average of 7 months after surgery (range, 4-16 months). Complaints/complications were minor: three had minor incisional symptoms, five had medial heel pain (3 caused by plantar fasciitis), and one had unchanged preoperative heel pain secondary to clubfoot deformity. Compared with more extensive bone-grafting procedures, this procedure offers the advantages of bone harvested under local anesthesia using a readily accessible ipsilateral extremity and producing minor complications.

Adolescent↗