Page 10 - DISCUSSION continued

In this series there were 3 breakages of the integrity of the nail itself. All 3 occurred in bilateral femoral lengthening for stature patients who were fully weight-bearing (without permission) early in the consolidation phase. All 3 occurred through the welds of the nail and all 3 showed preoperative varus bending of the nail. As there are no other published reports of Precice lengthenings, one cannot compare this complication to other series. However, anecdotal reports have arisen of 3 fractures at other centers also through the welds. In all but one case they occurred in bilateral lengthening cases. The weld is a weak point in the Precice 1 nail. This weakness is protected in unilateral cases by having 1 good leg to stand on and thus being able to unload the other leg with crutches. In bilateral cases unless the patient is only using a wheelchair they cannot really unload the femur with crutches or a walker.

Achieving the goal of lengthening is dependent on many factors. These include the reasonableness of the goal of lengthening relative to the pathology, obstacles, and complications that develop during lengthening that recommend against continued distraction, pain, length distraction time affecting time off school and work and/or school or work deadlines (such as timing of start of school year), economic, social, and family reasons. Many of these have nothing to do with the device, but rather with the slow, protracted lengthening process, and the need for frequent follow-up, physical therapy, daily pain medicine, etc. However, the device does impact the ability to achieve the goal in some cases. For example, the runaway nail scenario can lead to subluxation of a joint or nerve injury or failure of bone formation, etc. all of which will affect the decision to continue lengthening or not.

Among 10 patients (24 nails) with the Fitbone device, 2 patients (20%) did not reach anticipated length due to restricted knee movement. Both these patients were undergoing stature lengthening and had femoral and tibial lengthening. 22 In a smaller series (8 patients) using the same device, they achieved 93% (83% to 100%) planned length. However, 2 of the 8 patients were eliminated from this analysis due to nail failure.23

Using the ISKD nail lengthening of 33 limbs resulted in 32 achieving desired goals. However, 8 patients (8 limbs) required additional procedures (manipulation, fixator-assisted) to achieve this due to slow or no progression of distraction.27 Baumgart and colleague’s cohort of 12 patients attained complete length objectives in all patients. Interestingly, all these patients received unilateral lengthening, which eliminates many factors that may cause premature termination. Similarly to our series where most of these terminations were in our bilateral group, especially true with our stature lengthening patients with very subjective goals. Nevertheless, internal devices in previous and in our current series seem to have a good track record for obtaining desired lengths.

Pain is an important consideration with every lengthening method. Pain is an expected part of lengthening. The degree of pain does vary between external and internal fixation methods. Pin sites and pin infections as well as tethering of muscles and other soft tissues are believed to be a major cause of pain during lengthening with external fixation. As all of these are absent with implantable devices, the pain is related to stability, rate of distraction, physical therapy, and stretch of soft tissues. Although it is not possible to eliminate stretch, control of rate and stability of fixation is device dependent. Friction may also play a part and can be limited by the, type of reamers used (straight vs. flexible), amount of overreaming, as well as by the level of osteotomy (at apex of curvature of femur; leaving as short an amount of nail to drag on the moving segment).

Pain as already notes was a major factor with the Albizzia and ISKD. Both of these devices rotate through the callus. Such rotation leads to friction and muscle spasm pain. This type of pain has been notably absent from reports on the Fitbone and from the experience in this study.

Using devices that require no rotation like the motorized Fitbone, here was minimal or no pain on lengthening (Singh et al).22 However, of the 10 patients, who had 24 implants, only 2 achieved 60 mm. The rest were between 27 and 50 mm, with a mean of 40 mm/nail. In contrast, of the 31 patients using the Albizzia nail all experienced discomfort or pain during lengthening. Twelve patients (39%) required readmission to perform ratcheting under general anesthetic.38 Our Precice patients seem to have minimal to no pain during lengthening. Also, they are generally admitted on average 2 to 3 days before discharge on oral pain medications. Furthermore, small incisions are used to insert device limiting soft-tissue damage and scar formation.