The Lengthening of Short Upper Extremity Amputation Stumps
Robert M. Bernstein, M.D.; Hugh G. Watts, M.D.; Yoshio Setoguchi, M.D.; Cedars-Sinai Medical Center, Los Angeles & Shriners Hospitals for Children, Los Angeles
Children with very short congenital or acquired upper extremity amputation stumps present difficult fitting problems for the prosthetist. Because the function of the prosthesis is related to the level of the amputation stump that can be fit, a lower level prosthetic fitting results in a potentially higher level of upper extremity function. There are few options for the treatment of short upper extremity amputation stumps. These primarily involve stump modification and prosthetic modification. For example, for a moderately short below elbow stump, additional functional stump length can be attained by transferring the biceps tendon insertion to the coracoid process. This functionally increases the distance between the tip of the stump to the cubital crease, and may allow fitting of a below elbow prosthesis in a patient that would otherwise require fitting as an above elbow amputee. Step-up hinges and other modifications of the prosthesis are also possible in moderately short below elbow amputation stumps. However, in extremely short stumps, patients may have no other choice than to be fitted with a higher level prosthesis. Not only does this result in a lower level of function, but the prosthesis is also heavier, more cumbersome, and in warmer climates can result in difficulties with heat dissipation.
Another option that can be considered in very short upper extremity amputation stumps is lengthening of the stump. There are some reports that involve limited numbers of cases of lengthenings of very short below elbow stumps. Most have involved lengthening by the Ilizarov method or by transferring additional bone (such as the residual radius) to gain acute length. Watts reported his initial results of lengthening children with residual limbs, reporting on both humeral and ulnar lengthenings, as well as lower extremity lengthenings. We reviewed our experience with lengthenings of both very short above elbow and below elbow amputation stumps in children with regards to fitting, wear, and usage.
Pre-operative and post-operative radiographs were evaluated with regards to overall bone length as well as "stump length". To radiographically measure stump length, we arbitrarily defined this as the distance between the adjacent joint flexion crease and the tip of the distal bone. Because additional soft tissue beyond the tip of the bone does not provide any mechanical advantage for moving a prosthesis, this was not included in the overall stump length. In addition, bone proximal to the flexion crease also does not provide any mechanical support to prosthetic use, and was thus also excluded.
The surgical procedure involved simple corticotomy and application of an external fixator. A variety of lengtheners were used to allow for the pins to be placed as close together as possible. In some patients a original Hoffman external fixator (Richards) provided the best pin placement, and in others it was the Ilzarov (Richards) or Orthofix fixator. After a delay of 5-7 days, distraction was performed in a standard fashion at 0.25mm four times daily. An immediate postoperative radiograph was obtained to check pin placement, and subsequent radiographs were obtained at varying intervals to check lengthening and consolidation. Range of motion of the adjacent joint was encouraged. Each stump was lengthened until the skin overlying the stump appeared to be unable to tolerate further lengthening. The lengthener was removed when radiographic consolidation had occurred. The stump was then wrapped with an elastic bandage or placed in an elastic stocking to control swelling. After resolution of swelling, the stump was then fit with a prosthesis.
11 patients with 14 short upper extremity amputation stumps were identified that had undergone lengthening of the stump with at least 1 year follow-up. There were 7 males and 4 females, and the age at surgery ranged from 6-19 years, with a mean age of 13.7 years. Mean follow-up after surgery was 39 months. 7 amputations were related to trauma, 4 were related to burns (3 electrical), and 3 were congenital deficiencies. The stumps lengthened included 10 humeri and 4 ulna.
9 patients underwent lengthening to improve prosthetic fitting, and in two patients (3 limbs) lengthening was performed to improve non-prosthetic function. These two patients did not desire prosthetic fitting. Of the patients who desired prosthetic fitting, only 3 patients had been fit with a prosthesis pre-operatively, and all were able to be fitted with a lower level prosthesis post-operatively. Of the other 8 limbs in patients desiring prosthetic fitting, all but one were able to be fit post-operatively. 2 patients reported only utilizing the prosthesis on rare occasions for cosmetic reasons.
Mean bone length increased 75% (5.5 cm) and mean stump length increased 264% (4 cm) in those patients in which a stump length could be measured pre-operatively. 35 additional procedures were required in 10 patients. One patient was unable to comply with the lengthening and healed his osteotomy early, requiring fixator removal, reapplication and osteotomy, and subsequent stump revision. In addition, 4 tissue transfer procedures (1 local flap and 3 abdominal or chest wall flaps) were required in 3 patients.
Complications included 1 elbow and 2 shoulder subluxations, skin ulcerations in 3 patients, loss of elbow range of motion in 2 patients, and 1 pin-tract infection.
The treatment of short upper extremity amputation stumps is difficult and the lengthening of very short stumps remains controversial. Lengthening may allow a patient to be fit with a prosthesis who was previously unfittable because of the lack of a lever to activate the prosthesis. Very short below elbow amputees may only be able to function as if they were above elbow amputees. And very short above elbow amputees may only be able to function as shoulder disarticulations. Each additional proximal level of prosthetic fitting dramatically decreases the patients function. Thus, it seems reasonable to attempt lengthening in order to improve the patients prospects for a lower level prosthesis.
We were able to obtain significant length in most of our patients, and found similar results to other reports in mean overall increase in length achieved. In our series, it appears that the limiting factor in length gained is the soft tissue and skin at the tip of the stump. In general, we tried to gain as much length as possible and lengthened until the skin became quite taught over the tip of the stump. In spite of the skin problems, all but one stump was able to be fit with a prosthesis appropriate to the amputation level.
In spite of additional length gained in our patients, it was apparent that a number of our patients who were successfully fit with a prosthesis appropriate to the level of amputation did not utilize the prosthesis full time, and 2 reported rarely using the prosthesis. These facts may call into question the value of lengthening these stumps. These were not simple procedures and there were numerous complications. On the other hand, prosthetic wear in and of itself may not be a good measure of functional improvement. Many of our children were able to use their lengthened stumps more effectively (without a prosthesis), and in the future, they may choose to utilize a prosthesis more.
In two patients (both congenital above elbow amputees), the stumps were lengthened in order to improve non-prosthetic function. In one of these patients with bilateral short above elbow stumps, he was subsequently able to get his stumps to midline, improving his ability to grasp objects and play baseball. In the other patient, he was able to use the limited increase in stump length to grasp small objects such as paper or pencil.
Our one elbow subluxation occurred in a short below elbow stump in which we made the osteotomy proximal to the coracoid process. We feel that thiswas a technical error, since lenghtening proximal to the insertion of the brachialis tendon may have increased tension on the tendon, thus providing a posterior force to the elbow joint. We did not encounter this problem if the osteotomy was made distal to the coracoid. However, in very short below elbow stumps, obtaining purchase with the external fixator can be difficult, and a carefully made oblique osteotomy seems to be the best method. Because the triceps expansion inserts over a wide area on the ulna, it is not possible to avoid increasing tension in the triceps tendon. In two of our patients, we needed to perform a triceps lengthening and successfully improved their range of motion.
In two humeral stump lengthenings, we noted proximal subluxation of the humeral head. This may be related to a low lying humeral head with a widened acromio-humeral distance secondary to deltoid dysfunction. Many patients with short above elbow amputations have dysfunction of the deltoid and the humeral head drops. As the stump is lengthened, the humeral head is driven back up into the glenoid and may even be driven into the acromion. Thus, careful followup during the lengthening with regular shoulder radiographs should be considered.
Finally, this study raises a two additional questions. What determines whether upper extremity stump lengthening is a success? This could be based on a number of factors, such as the ability to fit an appropriate level prosthesis, the amount of time an amputee actually wears the prosthesis, whether the amputee actually utilizes the prosthesis (which may be different than wear), and improvement in non-prosthetic function . Future prosthetic use may also be a factor. And finally, how should we measure a stump? This could be measured as a percentage of the normal limb length utilizing either the soft tissue or the bone as the end of the stump, measuring the bone length radiographically, or measuring the bone length with reference to an arbitrary point (such as the proximal flexion crease). In the case of a below elbow amputation, clearly the bone proximal to the coracoid provides no additional lever with which to power a prosthesis. Answers to these two questions may help elucidate the controversy regarding the benefit of lengthening short upper extremity amputation stumps.