Wound Healing in Transtibial Amputees Related to Surgical Technique
Nora Cullen, MD, MSc, FRCPC
Michael Devlin, MD, FRCPC
ABSTRACT
Transtibial amputations (TTAs) have traditionally been surgically bevelled at the anterior tibia by a surgical saw. Furthermore, the fibula has been cut shorter than the distal tibia by 2 to 3 cm. It is thought that these two measures result in quicker wound healing by virtue of less of a "pressure point" irritating the soft tissue from sharp, bony angles.
In our rehabilitation practice of a largely dysvascular population, most TTAs presenting for prosthetic fitting and gait retraining at a rehabilitation hospital had the tibia bevelled and fibula shortened. However, a large number did not. It was our impression that the patients who had these measures taken had quicker healing of the surgical incision than those who did not. A review of the literature from 1965 to the present revealed that the issue has never been formally studied. There are only clinical impressions of various authors stating that, in their experience, it is better to bevel the tibia and shorten the fibula.
We have reviewed the radiographs and charts of 142 TTAs admitted to a rehabilitation facility between January of 1993 and December of 1995. We categorized the patients according to the types of surgical bone cuts and correlated them with the time from the date of surgery to the point of healing (as estimated by the date of first prosthetic fitting). Our results show that shortening the fibula at the time of TTA correlates with a shorter time to heal the wound (p = .046), but bevelling of the tibia is of questionable value in the dysvascular patient (p = .91).
Key Words: amputation,
transtibial, wound healing, surgical technique
Transtibial amputations (TTAs) have conventionally been surgically bevelled at the anterior tibia by a surgical saw, then carefully rounded with a rasp. The fibula is typically made shorter than the tibia by a few centimeters. Intuitively, it would seem that these two measures should result in quicker wound healing by decreasing pressure on the soft tissues from sharp, bony angles.
Most amputees presenting for prosthetic fitting and gait
retraining at a rehabilitation hospital had the above measures taken. However, a
significant number did not. It was our impression that the patients who received
bevelling of the anterior tibia and shortening of the fibula at the time of
surgery had quicker healing of their incision than those who did not. A review
of the literature from 1965 to the present revealed that the issue has never
been formally studied. There are only clinical impressions of various authors
stating that, in their experience, it is better to bevel and rasp anterior
distal cut tibia and shorten the fibula by 2 to 3 cm above the distal tibia to
obtain a conical stump.
Methods
The amputations were performed by multiple surgeons from multiple referring hospitals. A retrospective review of all 142 transtibial amputees admitted to a single rehabilitation facility during a 3-year period from January 1, 1993 to December 31, 1995 was performed. Radiographs of the residual limb were analyzed and categorized into one of the following four groups: NB/NS, not bevelled tibia (NB) and not shortened fibula (NS); B/NS, bevelled tibia (B) and not shortened fibula (NS); NB/S, not bevelled tibia (NB) and shortened fibula (S); and B/S, bevelled tibia (B) and shortened fibula (S).
It was arbitrarily decided that the bevelling of the tibia should demonstrate a rise of the slope of ). This was judged to result in an anterior edge that was less likely to impact on the anterior soft tissues. Shortening of the fibula was measured at <>1 cm above the distal tibia for the same reason.
A chart review was done to determine the time it took to achieve wound healing. This was estimated by subtracting the date of surgery from the date of first prosthetic fitting, resulting in the number of days it took to reach a level of incision healing judged adequate for prosthetic fitting. At that time, the standard was to have a clean wound with no drainage or open areas before prosthetic fitting. The patients were treated equally during the study period with respect to wound and stump care. The same team made the treatment decisions during the review period. We determined the demographics and comorbidities from the hospital data bank and obtained missing data from a chart review.
Exclusion criteria were a time to heal of <>1 year, traumatic TTAs, and those for whom we could not locate radiographs or charts. Those patients who required <>1 year to be fitted prosthetically had secondary issues such as a severe illness that prevented fitting. There were 142 patients in the final analysis.
Statistical analysis was done using the SAS system (SAS,
Cary, NC). An analysis of variance, analysis of covariance, and Student's
two-tail t test were done. Tukey's Studentized range test was done to control for Type I error.
Results
Demographics were analyzed for the four groups; the results are presented in Table 1
. There is no significant difference between these groups in terms of age, sex, or comorbidities.
The number of days that it took to reach adequate healing for fitting for each of the four groups is presented in Figure 2
. The group having the longest time to heal was the bevelled tibia and not shortened fibula (B/NS) group, 96.3 ± 14.9 days (mean ± sem). The next slowest to heal was the not bevelled, not shortened (NB/NS) group at 79.4 ± 13.1 days. The shortest time to heal was noted in the bevelled tibia, short fibula (B/S) group with 65.2 ± 5.1 days and the not bevelled tibia, short fibula (NB/S) group at 65.3 ± 8.3 days. The latter two groups were significant when tested against the B/NS group (Student's two-tail t test; p = .05 and p = .046, respectively) and adjusted for age.
We then looked at the combined bevelled groups (B/NS + B/S; n = 96) tested against the not bevelled groups (NB/NS + NB/S; n = 46) and analyzed them with Student's two-tail t test (Figure 3
, left). The results show that it required 69.4 ± 7.1 days (mean ± sem) for the not bevelled group to heal and 68.5 ± 4.9 days (mean ± sem) for those that had been bevelled to heal. This difference was not significant (p = .92).
A similar analysis was done of the groups with shortened fibula (B/S + NB/S, n = 119), comparing the time to heal with that of those not shortened at the fibula (B/NS + NB/NS, n = 23). The results of this analysis are shown in Figure 3
, right, and demonstrate that it required a mean of 86.8 ± 9.7 days (mean ± sem) for the not shortened fibula group to heal versus 65.3 ± 4.3 days (mean ± sem) for the short fibula group to achieve healing. The difference was significant when adjusted for age (p = .046).
There was no significant confounding factor among the four groups when compared by analysis of covariance. However, age of the patient at the time of fit was a significant predictor of the time to reach healing (p = .02). Older patients tended to heal slower than younger patients did.
Discussion
This study looks at the effects on wound healing of various surgical bone cuts in transtibial amputees. We have shown that the shortening of the fibula by >1 cm correlates with a significantly shorter time to wound healing than if this step is omitted. We speculate that the soft tissues are less taut when the fibula is shorter than the tibia, resulting in a more conical residual limb.
The bevelling of the tibia did not result in a significantly improved duration of time to achieve healing of the incision, contrary to what we were expecting. The lack of significance may reflect a wide variety of confounding variables in this population or a lack of power in our study. Possible unexamined factors that may have had an effect include poor nutrition, anemia, diabetic glucose control, and antibiotic use. Other aspects of surgery, such as handling of the bone, use of a rasp to smooth the cut end of the bone, myodesis versus myoplasty, and transcutaneous oxygen pressure, were assumed to be the same across the groups, but these were not examined in this study.
The patients had a similar comorbidity profile, and there were no traumatic TTAs. Therefore, the chances of healing based on internal factors were equal across the groups. Externally, the groups were treated in a similar manner. The same criteria were used to determine the time of first fitting. The prosthetists and physicians were the same across all groups.
Future research in this area could be directed toward the differences in the wound after prosthetic fitting to determine if the long-term consequences of various surgical bone cuts are similar to the short-term effects.
In conclusion, the conventional wisdom of shortening the fibula with respect to the tibia at the time of surgery appears to be a clinically useful technique. However, we were unable to demonstrate that the common practice of bevelling the tibia results in any clinical benefit.
Acknowledgements
We are grateful to Janice Walker,
Robert Shum, and David Cheng for their technical support and to the staff of the
Radiology Department of Westpark Hospital, Toronto, Ontario for their
cooperation.
References:
- Burgess EM, American Academy of Orthopaedic Surgeons.
Atlas of Limb Prosthetics: Surgical and Prosthetic Principles. St. Louis:
Mosby; 1981:14-18.
- Gerhardt JJ, King PS, Zettl JH.
Amputations--Immediate and Early Prosthetic Management. Bern, Stuttgart,
Vienna: Hans Huber Publishers; 1982:46-47.
- Gillis L. Amputations. London: William Heinemann
Medical Books; 1954:64-69.
- Lexier RR, Harrington IJ, Woods JM. Lower extremity
amputations. A 5-year review and comparative study. Can J Surg. 1987;30:374-376.
- Little JM. Major Amputations for Vascular Disease. Edinburgh, London, New York: Churchill-Livingstone;
1975:28-31.
- Penington G, Warmington S, Hull S, Freijah N. Rehabilitation of lower limb amputees and some implications for surgical management. Aust N Z J Surg 1992;62:774- 779.
|
