Harold B. Kitaoka

Clinical Rating Systems for the Ankle-Hindfoot, Midfoot, Hallux, and Lesser Toes

Four rating systems were developed by the American Orthopaedic Foot and Ankle Society to provide a standard method of reporting clinical status of the ankle and foot. The systems incorporate both subjective and objective factors into numerical scales to describe function, alignment, and pain.

Clinical Results of the Mayo Total Ankle Arthroplasty

Two hundred and four primary Mayo total ankle arthroplasties were performed in 179 patients at the Mayo Clinic from 1974 through 1988. We evaluated the clinical result after 160 arthroplasties in 143 patients who had been followed for two years or more (mean, nine years; range, two to seventeen years). The result was good for thirty-one ankles (19 per cent), fair for fifty-five (34 per cent), and poor for seventeen (11 per cent); fifty-seven arthroplasties (36 per cent) were considered to be a failure (defined as removal of the implant). Adequate preoperative and follow-up radiographs were available for 101 ankles (eighty-nine patients). There was radiographic evidence of loosening of eight tibial components (8 per cent) and fifty-eight talar components (57 per cent), but we found no association between the clinical and radiographic results. Complications occurred after nineteen (12 per cent) of the 160 arthroplasties, and ninety-four additional reoperations were necessary after sixty-six (41 per cent). On the basis of these findings, we do not recommend ankle arthroplasty with a constrained Mayo implant for rheumatoid arthritis or osteoarthrosis of the ankle.

Biomechanical Evaluation of Longitudinal Arch Stability

In spite of the common occurrence of pes planus and multiple operations that have been reported to relieve the associated symptoms, there is little published on the relative contribution of various structures to stabilization of the arch of the foot. Twelve fresh-frozen human cadaveric feet were loaded along the tibial axis with compressive loads of 230, 460, and 690 newtons with the specimens intact and after sequential sectioning of plantar fascia, plantar ligaments, and spring ligament. Structures were sectioned in six different sequences and changes in vertical and horizontal dimensions of the medial arch were measured. The highest relative contribution to arch stability was provided by the plantar fascia, followed by plantar ligaments and spring ligament. Plantar fascia was a major factor in maintenance of the medial longitudinal arch. Its division in the cadaveric feet decreased arch stiffness by 25%.

Plantar Fasciotomy for Intractable Plantar Fasciitis: Clinical Results and Biomechanical Evaluation*

Thirteen consecutive patients underwent plantar fasciotomy in 16 feet for intractable plantar fasciitis and had follow-up from 4.5 to 15 years. Plantar fasciotomy was successful (good or excellent results) for 71% of the 14 feet operated on and for which follow-up data were available. However, time to full recovery was prolonged, additional treatment was frequently required, and abnormalities of foot function persisted. Flattening of the longitudinal arch occurred. Dynamic force-plate studies showed differences in peak vertical, fore-aft, and lateralmedial forces between patients and matched controls. More rapid progression of weightbearing along the longitudinal axis of the foot during stance phase in patients indicated avoidance of heel loading.

Arthrodesis for failed ankle arthroplasty

Thirty-eight ankles in 36 patients who underwent fusion for failed total ankle arthroplasty were reviewed. Twenty-two patients were women and 14 were men, and their mean age was 56.8 years. The fusion methods performed in the 38 ankles were malleolar resection in 13, intercalated bone graft in 20, and posterior tibiotalocalcaneal fusion in 5. Fixation was external in 36 ankles and internal in 2. Bone graft was used in 32 ankles. Union was achieved in 33 ankles (89%). The average duration of the follow-up period in 29 patients (31 ankles) was 8.3 years (range, 2-14.4 years). Patients had no or mild pain in 24 ankles (80%). Complications occurred in five ankles (13%). Failed total ankle arthroplasty may be successfully salvaged by arthrodesis.

Survivorship analysis of the Mayo total ankle arthroplasty

From 1974 until the end of 1988, 204 primary Mayo total ankle arthroplasties were performed at the Mayo Clinic. By means of actuarial analysis, we determined the cumulative rates of survival with failure (defined as removal of the implant) as the end point. The average duration of follow-up was nine years (range, two to seventeen years). By applying the Cox proportional-hazards general linear model, we identified two independent variables that were associated with a significantly higher risk of failure: a previous operative procedure on the ipsilateral foot or ankle and an age of fifty-seven years or less. The overall cumulative rate of survival at five, ten, and fifteen years was 79, 65, and 61 per cent, respectively. The probability of an implant being in situ at ten years was 42 per cent for patients who were fifty-seven years old or less and who had had previous operative treatment of the ipsilateral ankle or foot and 73 per cent for those who were more than fifty-seven years old and who had had no such previous operative treatment. We do not recommend the use of the Mayo total ankle arthroplasty, particularly in younger patients who have had a previous operative procedure on the ipsilateral ankle or foot.

Displaced Intra-articular Fractures of the Calcaneus Treated Non-operatively. Clinical Results and Analysis of Motion and Ground-reaction and Temporal Forces

Twenty-seven patients who had a unilateral displaced intra-articular fracture of the calcaneus were managed with a cast instead of with reduction or an operation. The clinical result after a mean of six years (range, two to ten years) was excellent in five patients, good in five, fair in seven, and poor in ten. The sixteen patients who were re-examined for this study and for whom the gait was analyzed demonstrated abnormalities in ground-reaction force with regard to vertical force (F3) and temporal force factors (T2, T3, T6, and T9). Analysis of temporal and distance factors showed a trend toward a decreased proportion of single-limb support on the involved side. Three-dimensional motion analysis of the ankle and hindfoot was performed with electrogoniometers as the subject walked on a level surface, on a 10-degree side-slope, and up and down stairs. Motion was decreased in the sagittal, coronal, and transverse planes during walking on level ground and on a side-sloping surface. Significant decreases in motion in these planes were also seen during walking up and down stairs. Although these patients did not have a subsequent reconstructive operation, most had a residual functional deficit.

Revision of ankle arthrodesis with external fixation for non-union

We evaluated the cases of twenty-six patients (twenty-six ankles) who had had revision of an ankle arthrodesis with external fixation for a nonunion, to determine the reasons for the failure of the previous arthrodesis. Eighteen patients had had supplemental bone-grafting in addition to the external fixation. The failure of the previous arthrodesis was related to inadequate fixation technique in seven patients and to technical problems in two patients; in the other seventeen patients at least one risk factor was identified. We also determined the functional results of the revision operation with external fixation for all patients. The average duration of follow-up was five years (range, two to ten years) in the twenty-two patients who did not have a reoperation for a persistent nonunion. The results were excellent in eleven patients, good in five, fair in four, and poor in six. The over-all rate of union was twenty (77 per cent) of twenty-six, comparable with that after primary arthrodesis; however, supplemental bone-grafting is usually necessary. In the current series, rigid fixation, precise apposition of bone and alignment of the foot, and early treatment of perioperative infection gave satisfactory results.

Arthrodesis for the treatment of arthrosis of the ankle and osteonecrosis of the talus.

We evaluated the results of arthrodesis that had been performed for arthrosis of the ankle and osteonecrosis of the talus in nineteen patients. Twelve patients were men, and seven were women. The mean age of the patients was thirty-four years (range, nineteen to fifty-eight years). The median interval between the injury and the index operation was twenty-one months (range, six to 408 months). The arthrodesis was performed at the level of the ankle only in three patients and in both the ankle and the subtalar joint in sixteen. External fixation was used in thirteen patients, internal fixation was used in four, and no fixation was used in two. Supplemental bone graft from the iliac crest was used in fourteen patients, and local bone graft was used in five. The mean duration of follow-up was six years (range, two to fifteen years). The clinical result was excellent in seven patients, good in six, fair in three, and poor in three. Union was achieved in sixteen ankles, but it was delayed in one of them. Complications occurred in four patients: one had a tibial stress fracture, one had an infection at the site of a non-union, and two had malalignment in plantar flexion. Overall, the arthrodesis was successful in these patients. The use of rigid fixation and bone-grafting had a rate of success approximating that reported for primary arthrodesis in patients who do not have avascular necrosis.

Effect of the posterior tibial tendon on the arch of the foot during simulated weightbearing: Biomechanical analysis

A cadaver study was performed to determine the effect of the posterior tibial tendon (PTT) on the stability of the foot in simulated midstance phase of gait. Thirteen fresh-frozen human foot specimens were used. Loads were applied axially and to each tendon. Three-dimensional positions of tarsal bones before and after tendon loading were determined with the use of a magnetic tracking device. Significant differences in tarsal bone positions were observed with application of loads to the Achilles, posterior tibial, flexor digitorum longus, peroneus longus, and peroneus brevis tendons at the metatarsotalar, calcaneotalar, and talotibial joints and in overall arch height. These tendon loads caused position changes toward arch flattening or mild pes planus deformity. Significant differences in tarsal bone positions were observed with PTT loading compared with no PTT loading in metatarsotalar, calcaneotalar, and talotibial levels as well as arch height. The PTT caused position changes toward restoring the arch alignment. These data suggest that the PTT is an important stabilizer of the arch of the foot.