Thirty-eight of forty feet in the Ponseti group underwent an Achilles tenotomy, whereas forty-three of forty-six feet treated with below-the-knee casts underwent surgery. Forty-six percent (twelve) of twenty-six patients in the Ponseti group ultimately required surgical intervention other than percutaneous Achilles tenotomy. A posterior release was performed in one foot in the Ponseti group and in eleven feet in the surgical group. A full posteromedial release was required in three feet in the Ponseti group and thirty-one feet in the surgical group. One patient who initially was managed with below-the-knee casting and bracing for the treatment of bilateral deformity underwent a later unilateral Achilles tendon lengthening and a tibialis anterior tendon transfer, and this procedure was included among the primary surgical procedures. Three patients in the Ponseti group underwent recasting in an attempt to treat a recurrence, but two of the three had a failure and required additional surgery. Fourteen patients in the Ponseti group had minor problems (cast breakdown, kicking out of boots, skin irritation, sores, or blisters) with post-tenotomy casts and the abduction orthosis, whereas only four patients in the surgical group had similar problems. Two of the twelve patients requiring surgery in the Ponseti group and two of the twenty-seven in the surgical group had postoperative complications. In the surgical group, one postoperative urinary tract infection and one case of cellulitis were seen. In the Ponseti group, one patient undergoing a posteromedial release had subsequent wound slough and infection, and a second patient had an infection following a tibialis anterior tendon transfer. Only 35% (nine) of the twenty-six patients in the Ponseti group were compliant with post-tenotomy bracing, despite our requirement for only one full year of use (Table II).
After an average duration of follow-up of 3.5 years (range, 2.2 to 5.6 years) in the Ponseti group and 3.8 years (range, 2.2 to 5.7 years) in the surgical group, recurrences of clubfoot deformity occurred in both groups. Fourteen (30%) of the forty-six feet in the surgical group and fifteen (38%) of the forty feet in the Ponseti group were found to have recurrences requiring additional intervention. In terms of the number of patients (as opposed to feet), eight patients (thirteen lower extremities) required a total of fourteen additional procedures (surgical revisions) in the surgical group (with one individual having two revisions), and twelve patients (fourteen feet) in the Ponseti group required a total of fifteen surgeries (with one of these feet requiring a revision tibialis anterior tendon transfer). While no significant difference was seen between the groups in terms of the percentage of recurrence, the difference in the severity of recurrence was significant. Eleven (73%) of the fifteen recurrences in the Ponseti group and two (14%) of the fourteen recurrences in the surgical group were minor. Conversely, four (27%) of the fifteen recurrences in the Ponseti group and twelve (86%) of the fourteen recurrences in the surgical group were major. This difference in the severity of the recurrences was significant (p = 0.003) (Table III).
There may be a concern that using the foot as the unit of analysis may ignore a potential confounding effect of individuals with bilateral clubfoot deformity. Therefore, the analysis was also run with use of the subjects as the unit of analysis. By this measure, eight (28%) of the twenty-nine patients in the surgical group and twelve (46%) of the twenty-six patients in the Ponseti group had recurrences requiring additional intervention. While no significant difference was seen in terms of the percentage of recurrence (p = 0.17), the difference in the severity of recurrence remained significant (p ≤ 0.03). Nine of twelve patients in the Ponseti group and two of eight patients in the surgical group had a minor recurrence. Conversely, three of twelve patients in the Ponseti group and seven of eight patients in the surgical group had a major recurrence (with one patient in the surgical group having a minor recurrence and a later major recurrence involving the same foot).
Revision procedures were defined as those that were performed on feet that had already undergone a primary surgical procedure other than a percutaneous Achilles tenotomy. The percentage of feet that had a surgical revision in the surgical group was identical to the percentage of feet that had a recurrence (30%). Included in this figure is one patient who required two subsequent revisions (percutaneous tenotomy and open posterior release) after an initial posteromedial release. These were counted individually as two separate revisions. Conversely, despite a relatively high overall recurrence rate (38% [based on the number of feet] or 46% [based on the number of patients]), only one patient in the Ponseti group required additional surgery (a revision tibialis anterior tendon transfer) after the development of a postoperative infection. The difference in revision rates was significant (p = 0.03).
On multivariate analysis, the only significant explanatory variable was family history (p = 0.033). On the average, a family history increased the odds of recurrence by a factor of 3.81 (95% confidence interval, 1.11 to 13.04). The p values for treatment type, race, and Pirani score were 0.15, 0.94, and 0.41, respectively. A separate logistic regression for the Ponseti group alone showed that, with the numbers available, compliance with brace use was not a significant factor (p = 0.67).
Initial nonoperative management is the preferred method for the treatment of clubfoot in many institutions today24, largely because of the promising short and long-term results reported by Ponseti and others2,8,25-29. Although most surgical series have shown satisfactory outcomes6,30, a substantial number of feet require subsequent surgery4,6,30, and the potential for surgical complications exists at each intervention. In New Zealand, surgical treatment of this deformity has been the standard of care primarily because of the perception that this deformity is more severe in the New Zealand population than in other populations and that, in our population, compliance with an abduction orthosis would be low. Few studies have prospectively compared the results of operative and nonoperative treatment of clubfoot. Herzenberg et al.2 compared two different casting methods (traditional and Ponseti) and found the Ponseti method to be far superior, decreasing the need for operative intervention. In what we believe to be the only published report comparing the outcome of feet treated with a “Ponseti-like” technique and full surgical intervention, Ippolito et al.8 found that the long-term functional results for the Ponseti group were better than those for patients managed with more extensive surgery.
At our institution, two surgeons had differing opinions regarding the treatment of clubfoot. After receiving informed consent and an offer of randomization, almost all of the caregivers for our patients had strong preferences for choosing their treatment, with nearly half choosing the surgical treatment and half choosing the Ponseti method. Although the study population was not randomized, our demographic data showed that these two cohorts were very similar. Most importantly, the severity of deformity in each group was the same, with an initial average Pirani score of 5.2. We were surprised that an equal number of parents would choose surgical intervention over a primarily nonoperative method. One explanation may be that with the high incidence of clubfoot deformity in New Zealand, many families knew of other children who had done well with surgical correction. Thus, the more familiar surgical treatment may actually appear to be the more “conservative” treatment in comparison with the “new” casting technique that was only recently introduced (less than ten years previously) in New Zealand. Another potential reason is that the families may have viewed the surgical treatment as the more sophisticated or advanced treatment that may correlate with a superior outcome. Finally, brace wear was emphatically discussed with the families and, despite lowering the recommended total brace wear from the age of three to four years (as recommended by Ponseti) to one year, we still noted poor compliance with orthotic wear and the surgical treatment did not require routine brace wear.
The purpose of the present study was to compare the surgical and Ponseti treatment methods with regard to early outcomes in terms of recurrence and the need for additional surgery. Because we used preoperative casts in the surgical group, however, we can make comparisons between casting styles. The purpose of the below-the-knee casts that were applied in the surgical group was to help to stretch the feet for about six months in preparation for surgery. The goal of this casting was to partially correct the clubfoot deformity and to minimize the extent of surgery required. With 93% of these feet requiring surgery, 67% of the feet requiring a full posteromedial release, and 24% requiring only a posterior procedure, casting may have decreased the need for a full posteromedial release by as much as a third, but it is not possible to assess the effect that casting had on the subsequent surgery. What can be noted is the significant differences in terms of the number of casts, casting complications, and surgical requirements between casting styles. On the average, there were twice as many casts required and nearly four times as many cast-related problems (nineteen compared with five) in the surgical group. Despite the greater number of preoperative clinic visits and castings, a significantly higher percentage of patients required operative intervention (93% compared with 46%). These findings are similar to those that have been previously published2. The above-the-knee casts appear to hold the limb better, with fewer complications, and also perhaps help to derotate the tibia during the clubfoot correction.
Feet treated in both groups had a 30% to 40% rate of relapse, higher than that reported in the literature4,11, but similar to our previous report of a 41% rate of relapse22. This finding may reveal that some of the feet treated in New Zealand are more recalcitrant than those treated elsewhere. Lack of compliance with brace wear likely was a contributory factor in the recurrence rate in the Ponseti group11,22,25,31, despite attempts to improve compliance as reported previously by two of us22. This lack of compliance must be factored into clinical decision-making. If a patient population is not likely to be as compliant as those in previous reports, a reasonable portion of these deformities will recur, and results from other centers with high brace compliance rates do not provide a realistic comparison11. Although the rate of compliance with brace wear was low in the present study, it was not found to be a significant risk factor for recurrence in the logistic regression analysis, perhaps because of the small number of subjects in the Ponseti treatment group. Family history was found to be the only significant risk factor for recurrence in these cohorts.
An interesting point is the young age at which a major operative intervention was undertaken for the treatment of recurrence in the Ponseti group. Three of the four feet requiring major operative intervention were noted to have recurrences before the age of six months, and the other was noted to have recurrence by the age of eighteen months. These subsequently required major operative intervention at an average of nearly eighteen months of age. These cases may represent feet not fully corrected with the Ponseti method rather than true recurrences, as two were in a patient whose family was noncompliant with weekly casting.
In both groups, the question of undercorrection leading to later deformity as opposed to a true recurrence of a corrected deformity is difficult to address. For instance, the majority of the recurrences in the Ponseti group were not true recurrences of the deformity but rather were due to the dynamic action of the tibialis anterior muscle. The transfer of this muscle may not be considered to be a treatment of recurrence but rather a part of the initial Ponseti method as a long-term review of Ponseti's cases has shown the need for this tendon transfer in as many as 53% of cases26. We defined the need for these transfers as minor recurrences to allow for a more accurate comparison with feet that were treated surgically.
Statistically similar percentages of recurrences were found in both groups; however, with use of our modified classification system for recurrences, the extent of surgery that was needed to correct the recurrence in each group was different. This classification system is biased to the Ponseti method in that the treating surgeon for the Ponseti group (H.A.C.) attempted to avoid any intra-articular surgery unless absolutely necessary, whereas the treating surgeon for the surgical group (S.J.W.) did not attempt to limit this type of surgery if it would help to correct the deformity. Therefore, a selection bias may exist in the present study.
Any classification system has its strengths and weaknesses. The argument can be made that including a tibial derotational osteotomy in the major recurrence group is unfounded because the primary argument for this classification system is to measure the number of intra-articular procedures performed on the foot, which may in the long term cause foot stiffness. While we consider these long-bone osteotomies to be “major” surgery, their long-term effects on foot function and stiffness may not be as detrimental as repeated intra-articular surgery. Thus, if only intra-articular procedures (including those involving the use of a Kirschner wire to immobilize joints as in a lateral column lengthening) are considered (and extra-articular tibial derotational osteotomies are not), the significant difference in the types of recurrences is lost; however, the significant difference in surgical revision rates between groups remains.
While major surgical procedures are often more invasive than minor procedures, the difference in functional outcome between these types of interventions is not known. As the feet in the surgical group had undergone primary surgery, all subsequent procedures to correct recurrent deformities were by definition revision surgery. Conversely, all surgical procedures in the Ponseti group, except for the one revision tibialis anterior tendon transfer, were primary procedures. Following the long-term function of these revised feet will be important. Likewise, while the average duration of follow-up was 3.5 years for the Ponseti group and 3.8 years for the surgical group, many of the patients were quite young at the time of analysis. The deformities in these children may recur over time to require further operative intervention.
The present study is an early report comparing the treatment of idiopathic clubfoot. The findings in our New Zealand population indicate that the Ponseti treatment of clubfoot was associated with a decrease in the need for revision surgery when compared with primary surgical treatment. The percentages of feet that had a recurrence were similar in both groups, despite the fact that the majority of the feet in the surgical group underwent primary surgery and the finding that the majority of patients in the Ponseti group were noncompliant with abduction orthosis wear. In a recent parallel study, we showed the cost-effectiveness of the Ponseti method over the surgical method with use of these same cohorts32.
While the initial findings of the present study are important, long-term functional data on our patients are needed. In combination with other published findings, the results of the present study have caused changes at our institution. Currently, the casting method of choice is the Ponseti method throughout the institution.
Investigation performed at Starship Children's Health, Auckland, New Zealand
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.
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