Automated eye tracking system calibration using artificial neural networks.

The electro-oculogram (EOG) continues to be widely used to record eye movements especially in clinical settings. However, an efficient and accurate means of converting these recordings into eye position is lacking. An artificial neural network (ANN) that maps two-dimensional (2D) eye movement recordings into 2D eye positions can enhance the utility of such recordings. Multi-layer perceptrons (MLPs) with non-linear activation functions and trained with back propagation proved to be capable of calibrating simulated EOG data to a mean accuracy of 0.33 degrees . Linear perceptrons (LPs) were only nearly half as accurate. For five subjects, the mean accuracy provided by the MLPs was 1.09 degrees of visual angle ( degrees ) for EOG data, and 0.98 degrees for an infrared eye tracker. MLPs enabled calibration of 2D saccadic EOG to an accuracy not significantly different from that obtained with the infrared tracker. Using initial weights trained on another person reduced MLP training time, reaching convergence in as little as 20 iterations.

Operative treatment of interdigital neuroma. A long-term follow-up study.

BACKGROUND: The literature regarding the outcome of surgical treatment of interdigital neuroma is incomplete. The purpose of this study was to assess the demographics associated with the presentation of an interdigital neuroma as well as the long-term clinical results of operative resection by a single surgeon. METHODS: A retrospective review of the patient records of one orthopaedic foot and ankle surgeon identified eighty-two patients who had been treated operatively for a primary, persistently painful interdigital neuroma more than three years previously. Of these eighty-two patients, sixty-six (seventy-one feet, seventy-four neuromas) returned at an average of 5.8 years for a follow-up evaluation, which included a review of the interval history since the surgery, a physical examination, a radiographic evaluation, and an assessment of the patient's satisfaction with the result of the surgery. RESULTS: Overall satisfaction was rated as excellent or good by fifty-six (85%) of the sixty-six patients. Forty-six (65%) of the seventy-one feet were pain-free at the time of final follow-up. The patients who had had either bilateral neuroma excision or excisions of adjacent neuromas in the same foot in a staged fashion had a slightly lower level of satisfaction, but this difference was not significant. While major activity restrictions following surgery were uncommon, mild or major shoe-wear restrictions were noted by forty-six of the sixty-six patients. Although there was subjective numbness in thirty-six of the seventy-one feet, the pattern of numbness was quite variable and it was bothersome in only four feet. CONCLUSION: With careful preoperative evaluation and patient selection, resection of a symptomatic interdigital neuroma through a dorsal approach can result in a high percentage of successful results more than five years following the procedure.

Roger A. Mann Award . The reliability of angular measurements in hallux valgus deformities. .

The purpose of this study was to determine the intraobserver and inter-observer reliability of physicians on a repetitive basis in making angular measurements of hallux valgus deformities. The hallux valgus angle, the 1-2 intermetatarsal angle, and the distal metatarsal articular angle and the assessment of congruency/subluxation of the first MTP joint were evaluated on a repetitive basis. Physicians were provided with a series of black and white photographs of radiographs with a hallux valgus deformity. Three different sets of photographs randomly ordered were sent at a minimum interval of six weeks to the participants. Participating physicians were extremely reliable in the measurement of the 1-2 metatarsal angle. 96.7% of the photographs were repeatedly measured within a range of 5 degrees or less. The angular measurements to determine the hallux valgus angle were slightly less reliable, but 86.2% of photos were repeatedly measured within a range of 5 degrees or less. In the measurement of the distal metatarsal articular angle, 58.9% of photographs were repeatedly measured within a range of 5 degrees or less. There was a wide range within physician evaluators who recognized very few congruent joints (2 of 21) and those who recognized several congruent joints (11 of 21). Most physicians appeared to be internally consistent in the assessment of MTP congruency; however, some photographs were much more difficult to assess than others. This study validates the reliability of the measurement of the hallux valgus and the 1-2 metatarsal angle. The interobserver reliability in the measurement of the distal metatarsal articular angle is questioned.

Calcaneal fractures in the industrial patient.

A retrospective review was performed on industrial patients who sustained calcaneal fractures within the State of Idaho during the years 1992 to 1994, and these patients were insured by the Idaho State Insurance Fund. Of 48 calcaneal fractures that occurred during this period, 18 were non-displaced extra-articular fractures and 30 were displaced intra-articular fractures. An independent evaluator contacted each patient and performed chart reviews regarding the work history, period of time off work, and cost incurred with the injury. A total of 24 primary surgical procedures were performed on patients who sustained a displaced intra-articular calcaneal fracture and 31 secondary procedures were performed including wound debridement, hardware removal, skin grafting, and secondary subtalar fusion. For patients whose calcaneal fractures could be treated with non-operative care, the average time from injury until return to work was 18 weeks, and the average total cost of injury was $14,230. For patients whose calcaneal fractures required open reduction and internal fixation, the average time loss from work was 35 weeks, and the average total cost of injury was $31,004. Seven patients whose calcaneal fractures were initially treated with an open reduction, internal fixation later underwent a hindfoot arthrodesis. The average time off work for these patients was 69 weeks and the average total cost of injury was $65,384. Fractures were rated on postoperative radiographs according to the quality of their operative reduction. Fractures that were non-anatomically reduced had an increased tendency to require a subtalar fusion. Nine patients sustained other injuries associated with their calcaneal fracture and three patients sustained an open fracture. Both concurrent injuries and open fractures were associated with increased total cost and increased time off work. The total cost of injury was doubled as was time off work when an open reduction and internal fixation was followed later by a secondary subtalar arthrodesis.

Rheumatoid forefoot reconstruction. A long-term follow-up study.

BACKGROUND: The purpose of the present study was to assess the results of reconstruction of the rheumatoid forefoot with arthrodesis of the metatarsophalangeal joint of the great toe, resection arthroplasty of the metatarsal heads of the lesser toes, and open repair of hammer-toe deformity (arthrodesis of the proximal interphalangeal joint) of the lesser toes when this deformity was present. METHODS: A retrospective study of forty-three consecutive patients (fifty-eight feet) with severe rheumatoid forefoot deformities was performed. Six patients (six feet) died before the most recent follow-up, and five patients (five feet) were excluded because a subtotal procedure had been performed. No patient was lost to follow-up. Thus, the study included thirty-two patients (forty-seven feet) in whom reconstruction of a rheumatoid forefoot had been performed by the author. RESULTS: All first metatarsophalangeal joints had successfully fused at an average of seventy-four months (range, thirty-seven to 108 months) postoperatively. The average postoperative hallux valgus angle was 20 degrees and the average postoperative angle subtended by the axes of the proximal phalanx and the metatarsal of the second ray (the MTP-2 angle) was 14 degrees, demonstrating that a stable first ray protected the lateral rays from later subluxation. One hundred and thirty-two (70 percent) of the 188 lesser metatarsophalangeal joints were dislocated preoperatively, compared with thirteen (7 percent) postoperatively. The result of the procedure (as rated subjectively by the patient) was excellent for twenty-three feet, good for twenty-two, and fair for two. There were no poor results. The average postoperative score according to the system of the American Orthopaedic Foot and Ankle Society was 69 points. Postoperative pain was rated as absent in eighteen feet, mild in twenty-five, moderate in four, and severe in none. Fifteen feet were not associated with any functional limitations, twenty-eight were associated with limitation of recreational activities, and four were associated with limitation of daily activities. At the time of the most recent follow-up, no special shoe requirements were reported. Fourteen feet (30 percent) had a reoperation for the removal of hardware from the first metatarsophalangeal joint, a procedure on the interphalangeal joint of the great toe, or additional procedures on the lesser toes or lesser metatarsophalangeal joints. CONCLUSIONS: In the present study, arthrodesis of the first metatarsophalangeal joint, resection arthroplasty of the lesser metatarsal heads, and repair of fixed hammer-toe deformities with intramedullary Kirschnerwire fixation resulted in a stable repair with a high percentage of successful results at an average of six years after the procedures.

Operative repair of the fixed hammertoe deformity.

Sixty-three patients (118 toes) were evaluated at an average 61 month follow-up following PIP resection arthroplasty for a fixed hammertoe deformity. The deformity involved the second toe in 35%, the third toe in 21%, the fourth toe in 24%, and the fifth toe in 20%. The involved toe averaged 2 mm. greater length than the adjacent toes and was longer in 49/94 (52%). Seventy-eight percent of patients complained of pain preoperatively due to the hammertoe deformity and 49% complained of callus formation. Following a resection arthroplasty technique with intramedullary Kirschner wire fixation, fusion of the PIP joint occurred in 81% of toes. A fibrous union resulted in the remaining 19% of cases. Patients rated subjective alignment as acceptable in 86% of cases and radiographic alignment was rated as good in 79%. Malalignment and numbness were the major factors associated with an unsuccessful result. Pain was relieved in 92%of patients and subjective satisfaction was noted by 84% of patients. Minor complications occurred in 5%. The average postoperative AOFAS score was 83 points. Resection arthroplasty of the proximal interphalangeal joint with intramedullary Kirschner wire fixation as a technique for correction of a fixed hammertoe deformity is a reliable technique that consistently gives a high level of satisfactory results.

Treatment of hallux valgus with an increased distal metatarsal articular angle: evaluation of double and triple first ray osteotomies.

During a 12-year period in which 878 hallux valgus corrections were performed, 18 patients (21 feet) with symptomatic hallux valgus deformity and an increased distal metatarsal articular angle (DMAA) underwent periarticular osteotomies (double or triple first ray osteotomies). They were studied retrospectively at an average follow-up of 33 months. The surgical technique comprised a closing wedge distal first metatarsal osteotomy combined with either a proximal first metatarsal osteotomy or an opening wedge cuneiform osteotomy (double osteotomy). When a phalangeal osteotomy was added, the procedure was termed a "triple osteotomy." The average age of the patients at the time of surgery was 26 years. At final follow-up, the average hallux valgus correction measured 23 degrees and the average 1-2 intermetatarsal angle correction was 9 degrees. The DMAA averaged 23 degrees preoperatively and was corrected to an average of 9 degrees postoperatively. One patient developed a postoperative hallux varus deformity, and one patient developed a malunion, both of which required a second surgery. A hallux valgus deformity with an increased DMAA can be successfully treated with multiple first ray osteotomies that maintain articular congruity of the first metatarsophalangeal joint.

Hallux valgus in men: effect of the distal metatarsal articular angle on hallux valgus correction.

The results of hallux valgus correction were reviewed for 34 male patients (41 feet). The severity of the preoperative deformity determined the operative technique of correction. A distal soft tissue procedure with proximal first metatarsal osteotomy was performed in 30 patients (35 feet) with an average correction of the hallux valgus angle of 22 degrees. A chevron procedure was performed in five cases and a McBride procedure in one other case, all with less severe deformities. Complications included one deep wound infection, one broken screw at the metatarsal osteotomy site, and three cases of hallux varus. No patients underwent reoperation. Undercorrection was noted in 10 of 35 cases (29%) where a distal soft tissue procedure with proximal first metatarsal osteotomy was performed. A nonsubluxated (congruent) metatarsophalangeal (MTP) joint associated with a hallux valgus deformity was present in 15 of 41 (37%) of all cases and 10 of 35 (29%) of cases that underwent a distal soft tissue procedure with proximal metatarsal osteotomy (DSTR with PMO). A subluxated (noncongruent) MTP joint associated with hallux valgus was present in 26 of 41 (63%) of all cases and 25 of 35 (71%) of cases undergoing a DSTR with PMO. There was a highly significant difference in the average distal metatarsal articular angle (DMAA) as measured in the nonsubluxated (congruent) MTP joints (20.7 degrees) and the subluxated (noncongruent) MTP joints with hallux valgus (10 degrees) (P = 0.0001). The average distal metatarsal articular angle for all cases undergoing DSTR with PMO was 13 degrees. When the postoperative hallux valgus angle was compared with DMAA, the average residual hallux valgus angle was 10.1 degrees. With a subluxated (noncongruent) first MTP joint with hallux valgus (a low DMAA), the percent of hallux valgus correction (hallux valgus correction [in degrees]/preoperative hallux valgus deformity [in degrees]) was 77%. In patients with a nonsubluxated (congruent) first MTP joint with hallux valgus (a high DMAA), the percent correction was 46%, an almost twofold difference in percent correction. There was a close correlation between the preoperative DMAA and the postoperative hallux valgus angle in both the subluxated and congruent subgroups (P = 0.0003). With an intra-articular repair (a DSTP with PMO), the magnitude of correction of a hallux valgus deformity is limited at the MTP joint by the distal metatarsal articular angle.

Roger A. Mann Award. Juvenile hallux valgus: etiology and treatment.

In an 11-year retrospective study of 45 patients (60 feet) with juvenile hallux valgus, a multiprocedural approach was used to surgically correct the deformity. A Chevron osteotomy or McBride procedure was used for mild deformities, a distal soft tissue procedure with proximal first metatarsal osteotomy was used for moderate and severe deformities with MTP subluxation, and a double osteotomy (extra-articular correction) was used for moderate and severe deformities with an increased distal metatarsal articular angle (DMAA). The average hallux valgus correction was 17.2 degrees and the average correction of the 1-2 intermetatarsal angle was 5.3 degrees. Good and excellent results were obtained in 92% of cases using a multiprocedural approach. Eighty-eight percent of patients were female and 40% of deformities occurred at age 10 or younger. Early onset was characterized by increased deformity and an increased DMAA. Maternal transmission was noted in 72% of patients. An increased distal metatarsal articular angle was noted in 48% of cases. With subluxation of the first MTP joint, the average DMAA was 7.9 degrees. With a congruent joint, the average DMAA was 15.3 degrees. In patients where hallux valgus occurred at age 10 or younger, the DMAA was increased. First metatarsal length was compared with second metatarsal length. While the incidence of a long first metatarsal was similar to that in the normal population (30%), the DMAA was 15.8 degrees for a long first metatarsal and 6.0 degrees for a short first metatarsal. An increased DMAA may be the defining characteristic of juvenile hallux valgus. The success of surgical correction of a juvenile hallux valgus deformity is intimately associated with the magnitude of the DMAA. Moderate and severe pes planus occurred in 17% of cases, which was no different than the incidence in the normal population. No recurrences occurred in the presence of pes planus. Pes planus was not thought to have an affect on occurrence or recurrence of deformity. Moderate and severe metatarsus adductus was noted in 22% of cases, a rate much higher than that in the normal population. The presence of metatarsus adductus did not affect the preoperative hallux valgus angle or the average surgical correction of the hallux valgus angle. Constricting footwear was noted by only 24% of patients as playing a role in the development of juvenile hallux valgus. There were six recurrences of the deformities and eight complications (six cases of postoperative hallux varus, one case of wire breakage, and one case of undercorrection).

Operative repair of the mallet toe deformity.

Over a 14-year period, 60 patients (86 toes) underwent resection arthroplasty of the proximal interphalangeal joint for a mallet toe deformity. During the same period, 788 hammertoe corrections were performed, for a ratio of 9:1 hammertoe to mallet toe corrections. Fifty patients (72 toes) were evaluated at an average 55-month follow-up. In 53 toes (73%), the involved toe was longer than the adjacent toes. The second, third, and fourth toes were almost equally involved with a mallet toe deformity. With a resection arthroplasty technique, an arthrodesis of the PIP joint occurred in 52 toes (72%) and a fibrous union occurred in the remaining 20 toes (28%). Overall, 86% of the toes were rated as satisfactory by the patient (P < .001). A slightly lower satisfaction rate (75%) was noted in those toes with a fibrous union. A flexor tenotomy was performed in 22 toes along with the mallet toe repair. Acceptable alignment was noted in 96% of toes with a flexor tenotomy, and in 90% where a mallet toe repair was performed without a flexor tenotomy [corrected]. Pain was relieved (97%), correction was well maintained (91%), and patient subjective satisfaction was high (86%) with this procedure. Minor complications occurred in 14% of cases; however, one fourth of these patients still noted a satisfactory result.

Arthrodesis of the first metatarsophalangeal joint with Vitallium plate fixation.

Forty-seven patients (58 feet) underwent first metatarsophalangeal joint fusion with a small Vitallium plate (Howmedica, Inc., Rutherford, NJ). Congruous joint surfaces were prepared with either cone-shaped or cup-shaped reamers. At an average follow-up of 19.2 months, 98% (57 feet) were successfully fused. Ninety-three percent (54 feet) noted good or excellent results. Plate removal was necessary in only 7% (4 feet) of cases. Complications included nonunion with plate breakage in 2% (1 foot) and delayed union in 2% (1 foot) of cases. This technique was useful and predictable in achieving successful fusion of the first metatarsophalangeal joint.

Second metatarsophalangeal joint instability in the athlete.

In a group of athletically active patients, second metatarsophalangeal joint instability was diagnosed in nine patients (11 toes). A positive drawer sign was pathognomonic of early second metatarsophalangeal joint instability. A soft tissue realignment procedure was used to stabilize the second metatarsophalangeal joint in seven toes. In five of seven cases (71%), good to excellent results were noted at an average follow-up of 20.4 months.