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To better delineate between incomplete clubfoot correction and true clubfoot recurrence based on the time at which the deformity reappears and the treatment necessary to correct the foot.
A chart review of all idiopathic clubfoot at a single institution treated by either the Ponseti method or short leg casting and surgery were reviewed for recurrent deformity involving the tibia, ankle, or foot. Comparisons of treatment required to correct deformities were made between those noticed within six months of initial treatment and those noticed after six months. Similar comparisons were made based on the initial treatment of the deformity.
Forty-four of 51 patients showed some clinical deformities after their initial treatment. Over half of these deformities either resolved or did not require operative intervention at a minimum of two years follow-up, while 43% (19/44) were felt to require surgery. Eight patients had deformities re-appear within six months of initial treatment and eleven patients after six months. Six of the eight patients requiring surgery with deformities noticed less than six months after initial treatment required correction of structural deformities (osteotomies and posterior-medial releases), whereas 10/11 patients requiring surgery for deformities noticed after six months required correction for dynamic deformities. These differences were significant (p=0.01). No difference in terms of the number of deformities noticed (22/25 and 22/26) and number requiring surgery (11/22 in the Ponseti group and 8/22 in the surgical group) were found. However, deformities requiring further surgery in the surgical group re-appeared earlier 0.23±0.2 years than those in the Ponstei group 1.7±1 years (p=0.001). These earlier re-appearing deformities required more structural surgery (6/8) than those in the later appearing Ponseti group (1/11; p=0.01).
Nearly half of all re-appearing deformities required surgery. The deformities noticed within six months of initial correction required more structural surgery to correct than those noticed after six months. We propose that the recurrent deformities noticed before six months of age represent incomplete corrections and those after six months true recurrences. Feet initially treated with surgery may be more prone to incomplete correction whereas those treated by the Ponseti method may be more prone to recurrence.
Not all re-appearing clubfoot deformities are the same. The initial treatment and time at which they first appear may have implications as to the surgery required to correct.
Clubfoot is a common orthopaedic problem in New Zealand. While the entire population of New Zealand is 4 million, 750,000 people claimed Polynesian ethnic background in the 2001 census.1 With an estimated incidence of 6.8 clubfeet per 1000 in Polynesian populations,2 compared with one per 1000 in white European populations, pediatric orthopaedic surgeons in New Zealand encounter an unusually high number of clubfeet. Using this unique population we have previously published the short term results of clubfeet managed by either surgical release or the Ponseti method.3,4 In both treatment groups, we had a higher recurrence rate requiring further surgical intervention than previously described in the literature.5-8 With this relatively high recurrence rate in both prospective cohorts, the authors hoped to retrospectively analyze all patients with recurrent deformities. We attempted to answer four questions. (1) What percentage of feet showing even slight abnormalities after initial correction will require further surgery? (2) Could we discern between incomplete correction and true recurrence based on time after initial treatment that the first signs of deformity resurfaced? (3) Did the surgery required to correct these recurrences differ based on the time the deformities were first noted? (4) Would there be any differences in these factors between initial treatment options (Ponseti versus Surgical). We hypothesized that a relatively high percentage of patients in both groups would show early recurrent deformities, that recurrent deformity within 6 months of initial treatment likely represented incomplete correction and that these patients would require more structural surgery to correct. From our previous review of these patients we felt it likely that the initially treated surgical feet showing a recurrence would require more structural surgery.
In November 2001, after obtaining medical ethical board approval, until January 2005, all patients referred to our institution that were offered the above treatment options for clubfoot treatment were eligible for this study.
Only patients with idiopathic clubfeet and a minimum 2 years follow up from their initial casting were included. Fifty-five patients with 86 clubfeet met these inclusion criteria. Twenty–six patients (40 feet) were in the Ponseti group and twenty-nine (46 feet) in the below knee casting and surgery group. Clinical data was collected prospectively at each clinic visit using a templated data sheet as well as dictated notes. At the time of presentation the clubfoot deformities were graded using the validated 6-point scale of Pirani et al.9 Each group was managed by each treating surgeon and in depth initial treatment protocols can be found in our previously published studies.4 Briefly, the patients in the Ponseti group were managed with weekly casting, followed by percutaneous Achilles tenotomy, and placement into abduction orthosis. Those in the surgical group were treated with weekly or biweekly below knee casts until six months of age when surgical correction, often posterior or posterior-medial release, of the feet was performed.
We then reviewed the available clinical records including the prospective clubfoot worksheet, clinic charts, electronic charts, and operative records of all patients having minimum 2 year follow-up. These were reviewed for any mention of recurrent deformity noted. All abnormalities involving the lower extremities were initially included. These were then selected out for those involving the tibia, ankle, and feet. The date first noticed and the type of deformity noted in the patient's record was recorded. Once a recurrent deformity had been noted in the chart we followed the natural history of that deformity, recording spontaneous resolution, continued observation, or any treatments planned or employed either surgical or non-surgical. Common clinical findings included rotational deformities of the tibia, equinus of the heel cord, metatarsus adductus, dynamic supination of the forefoot, and overall tightness of the foot. When more than one deformity was noticed, ie tibial torsion and metatarsus adductus, the deformity most pertaining to the foot was included. In some of the patients no distinct mention of the deformity could be found, yet the patient went on to require further treatment. These were felt to be “generalized recurrences.”
Statistical analysis was performed to compare the time from the end of initial treatment that the recurrences were first noticed, the type of recurrence, and the time from initial correction that further treatment was deemed necessary, and the nature of that treatment. The patient rather than the individual foot was used as the unit of analysis. In the Ponseti group the end of initial treatment was defined as the date the child was placed into the Denis Brown bar and boots. For the surgical group, the date the last surgical cast/splint was used for this date. Patients that were unable to finish weekly Ponseti casting were eliminated from this group as were the patients not requiring either an intitial posterior or posteriormedial in the surgical group. Comparison between each cohort was then performed for patient's demonstrating a clinically noticeable deformity. For continuous variables a student T-test was used, for categorical variables 2-tailed Fisher's Exact test was used. A p-value less than or equal to 0.05 was defined as statistically significant.
In the Ponseti group 25/26 met inclusion criteria, whereas 26/29 patients in the surgical group met inclusion criteria. A high percentage of patients in both groups (22/25 and 22/26 respectively) were found to show some clinical deformities. Similarly, 11/22 in the Ponseti group and 8/22 in the surgical group showed early clinical abnormalities and were felt to eventually require surgery. The differences between these groups for the number of recurrent deformities and the number requiring surgery were not statistically different (p=l and p=0.54). The deformities noticed were similar in both groups with no significant difference found (Table 1). The time elapsed, after initial treatment until these abnormalities were first recognized, however was significantly different. On average, clinically apparent deformities were recognized at 0.7 (+/−1) years from initial correction in the surgical group and at 1.45 (+/−1) years of age in the Ponseti group (p=0.01). Likewise, the patients eventually requiring surgery in each of these groups showed an even larger difference in time between the end of initial treatment and first detection of recurrent deformity, as the average time in the surgical group was 0.23(+/−0.2) years and those in the Ponseti group 1.7 (+/−1) years (Figure 1). Three patients in each group underwent re-casting (after initial correction); two out of three in the Ponseti group and all three in the surgical group required operative intervention. A delay between recognition of the early recurrent deformities and the time they were addressed (time from end of initial treatment until surgical decision was made) was seen in both groups and was found not to be significant (2.69+/−1.3 years in Ponseti group versus 1.84 years in the surgical group, p=0.14). Finally, a statistical difference in the type of surgery required to correct these deformities was found. The authors defined soft tissue procedures such as tibialis anterior transfers, tendo-achilles lengthenings, and even posterior releases to be corrective of dynamic deformities; while full posterior-medial releases with or without pinning and osteotomies to constitute structural deformities. 7/8 of the patients requiring surgery with deformities noticed less than 6 months after initial correction required correction of structural deformities, whereas 10/11 patients requiring surgery for deformities noticed after 6 months of initial correction required correction for dynamic deformities. As the majority (7/8) of surgical patients were recognized earlier than the Ponseti group (1/11); the surgical group required correction of more structural deformities (Figure 1 and Table 2).
Utilizing a relatively high recurrence rate in both surgically and Ponseti treated clubfeet, in cohorts that had been assembled and followed prospectively, we set out to answer several questions regarding clubfoot recurrences. This is the first study of this type to be found in the literature. Other studies discuss recurrences as treatment failures,3,10-16 surgical options,12,17,18 and in terms of functional results.5,19 In this study we begin to answer four unknown questions.
What percentage of feet showing even slight abnormalities after initial correction required further surgery? In our study population between thirty-five to fifty percent of patients noted to have small early recurrent deformities went on to require further surgical treatment. This was seen for both cohorts and was essentially irrespective of age. Both cohorts had a high percentage (84% in the surgical group and 88% in the Ponseti group) of individuals showing some residual signs of the initial deformity. No statistical difference in the deformities noted could be elicited from our data. These deformities were often noted sooner after initial treatment in the surgical cohort and later in the Ponseti group. Fifty percent of these early recurrent deformities in the Ponseti group and thirty-six percent of the surgical group required further treatment (statistically not significant).
Could we discern between incomplete correction and true recurrence based on time after initial treatment that the first signs of deformity resurfaced? We believe that by using 6 months after initial treatment as a cut-off point, we could identify the recurrences that were most likely an incomplete correction or at least an early failure to maintain correction as opposed to a true recurrence (a foot that was corrected and then over time recurs). Sixteen of 44 patients showed recurrent deformities within the first 6 months after treatment (average 0.2 +/−0.15 years); while 28/44 patients had later recurrences (1.5 +/−1 years). 50% of the early deformities required surgical intervention and 40% of the later deformities required intervention.
Did the surgery required to correct these recurrences differ based on the time the deformities were first noted? From our data, it appears that those early deformities (<6 month from initial treatment) that do not spontaneously resolve or resolve with re-casting; often (7/8 patients) require much more extensive surgery to correct involving repetitive posterior-medial releases or osteotomies. We feel this type of surgery demonstrates the structural nature of the deformities that were not fully corrected or could not be maintained immediately after the initial procedure. Conversely, the deformities that surfaced later (>6months); required less invasive surgery often involved a tibialis tendon transfer, tendo-achilles lengthening, or even a posterior release. These we feel demonstrate a true recurrence and thus are dynamic in nature, i.e., the foot was in a corrected position, cartilaginous bones remodel to there new shape and position, and over time a recurrence occurs due to: anterior tibialis over-pull or gradual tendo-achilles contracture which might also lead to posterior capsular tightness. Thus the surgery to re-correct the foot is more soft tissue and dynamic in nature.
Would there be any differences in these factors between initial treatment options (Ponseti versus Surgical)? Eighty-four percent of the surgically treated clubfeet went on to have early recurrent deformities at a statistically earlier time (0.2 versus 1.7 years) than the Ponseti group. Thirty-six percent of these patients required further surgery as opposed to 50% of the Ponseti group. However, 7/8 patients in the surgical group required structural surgery to correct these deformities as opposed to the 1/11 in the Ponseti group. We believe these differences to represent a higher incidence of incomplete corrections in surgical group demonstrated by the much earlier noticed deformity (0.2 years after correction) and the type of surgery required to correct the deformity. Whereas the deformities in the Ponseti group were noticed later (average 1.7 years). This makes logical sense as the Ponseti casting has been shown, by Pirani et al through MRI imaging,20 to mold the pliable cartilaginous bones into their correct position and assume a more normal shape; however this casting in no way alters muscular forces affecting the foot. While surgical release abruptly changes the overall relationships between bones, it does not immediately change their shape. Unless the bones re-model while pinned or the healing scar tissue is strong enough to hold the bones in their new position the correction will be incomplete or will quickly return as the misshapen bones assume a more stable configuration. As this is generally done at a later age than the casting (average 6 months in this cohort); the bones of the foot may be less pliable.
Major limitations of this study need to be pointed out. First while starting out with relatively large prospective cohorts, we chose to look primarily at those patients with recurrences, thus limiting our sample size. We also used a two year minimum follow-up (average follow up of roughly 3.5 years) as inclusion criteria. Additional recurrences may continue to be found as time goes on. Despite the records of these children being recorded prospectively, no standardized objective criteria were initially established to designate an early recurrent deformity. Instead the authors relied on subjective references in the patients chart concerning the first recognition of a recurrent deformity while under the care of different clinicians. Despite these weaknesses, we feel that in general the evaluating clinicians put forth honest evaluations and looking at the overall numbers between cohorts in terms of number of overall patients with clinically noticeable deformities and number of deformities requiring surgical correction the evaluation of these groups appears very similar.
This is the first manuscript to evaluate the differences in the recurrences between surgically managed and Ponseti treated clubfeet. We believe this manuscript gives the clinician some knowledge as to what the natural history of an early recurrent deformity will be after the initial treatment of a clubfoot deformity. Furthermore, it may help to further explain the reported long-term functional differences between surgically corrected clubfeet and Ponseti treated clubfeet. Perhaps the majority of recurrences reported in the literature in surgically treated clubfeet are really incomplete corrections resulting in malformed bones and incongruent joints, thus requiring more structural surgery to further correct and resulting in foot stiffness; whereas the Ponseti recurrences, represent true recurrences do to dynamic forces acting on a corrected clubfoot? By following our large prospective cohort in the future, we hope to be able to answer these questions in the future.
From this study, nearly half of all re-appearing deformities required surgery. The deformities noticed within six months of initial correction required more structural surgery to correct than those noticed after six months. We propose that the recurrent deformities noticed before six months of age represent incomplete corrections and those after six months true recurrences. Feet initially treated with surgery may be more prone to incomplete correction whereas those treated by the Ponseti method may be more prone to recurrence. Thus not all re-appearing clubfoot deformities are the same. The initial treatment and time at which they first appear may have implications as to the surgery required to correct.