Complications and risk factors of intramedullary bone lengthening nails: a retrospective multicenter cohort study of 314 FITBONE and PRECICE nails.

BACKGROUND AND PURPOSE: Intramedullary bone-lengthening nails have become increasingly popular. The 2 most used and successful nails are the FITBONE and the PRECICE nails. Uniform reporting is lacking on complications of intramedullary bone-lengthening nails. The purpose was therefore to assess and categorize the complications of lower limb bone-lengthening nails and investigate risk factors. PATIENTS AND METHODS: We performed a retrospective review of patients operated on with intramedullary lengthening nails at 2 hospitals. We included only lower limb lengthening with FITBONE and PRECICE nails. Recorded patient data was patient demographics, nail information, and any complication. Complications were graded according to severity and origin classification. Complication risk factors were assessed with modified Poisson regression. RESULTS: 314 segments in 257 patients were included. The FITBONE nail was predominantly used (75%), and most of the lengthenings were performed in the femur (80%). 53% of the patients had complications. 269 complications were identified in 175 segments (144 patients). Device-related complications were most frequent (0.3 complications/segment), followed by joint complications (0.2 complications/segment). An increased relative risk was found for complications in the tibia compared with the femur and for age groups above 30 years compared with the 10-19 years group. CONCLUSION: Complications with intramedullary bone lengthening nails were more frequent than has previously been reported, with 53% of patients sustaining a complication. Future studies need to document the complications meticulously so that the true risk can be established.

Complications in Elective Removal of 271 Bone Lengthening Nails (FITBONE, PRECICE and STRYDE).

BACKGROUND: Intramedullary lengthening nails have shown excellent short-term results. The FITBONE and the PRECICE nail are the two most commonly used intramedullary lengthening nails. The manufacturer of each nail recommends the removal of the implant after the completion of the treatment. Despite the need for removal of each nail, the authors are not aware of any prior publications documenting the results of standard intramedullary lengthening nail removal. Therefore, the aim of this study was to examine the intraoperative and postoperative complications of elective intramedullary lengthening nail removals. MATERIALS AND METHODS: We performed a retrospective chart review of patients operated with intramedullary lengthening nails at two limb reconstruction centres (one in the United States, and the second in Denmark). Data retrieved from the patient charts included patient demographics, nail information and any complications occurring at or after nail removal. Only lower limb lengthening with FITBONE and PRECICE or STRYDE nails that had an elective nail removal was included. RESULT: A total of 271 elective nail removals were included in the study. Complications occurred during 3% of the nail removals and in 13% after nail removal. There were 18 reported cases with postoperative knee pain. All these patients had nail removal through the knee joint, representing 8% of the retrograde femur nail removals and 7% of the tibia nail removals. Four postoperative fractures occurred, of which two needed surgery. Eleven percent of femur removals and 26% of tibial removals sustained a complication. CONCLUSION AND CLINICAL SIGNIFICANCE: This study emphasises the importance of adequate follow-up of the bone lengthening patient even after the nail has been removed. It also shows that the recommended removal of the intramedullary nail (IMN) lengthening nails must be included in studies reporting on the overall risks of complications using bone lengthening nails. HOW TO CITE THIS ARTICLE: Frost MW, Kold S, Rahbek O, et al. Complications in Elective Removal of 271 Bone Lengthening Nails (FITBONE, PRECICE and STRYDE). Strategies Trauma Limb Reconstr 2021;16(2):110-115.

Systematic review of complications with externally controlled motorized intramedullary bone lengthening nails (FITBONE and PRECICE) in 983 segments.

Background and purpose - In recent years motorized intramedullary lengthening nails have become increasingly popular. Complications are heterogeneously reported in small case series and therefore we made a systematic review of complications occurring in lower limb lengthening with externally controlled motorized intramedullary bone lengthening nails.Methods - We performed a systematic search in PubMed, EMBASE, and the Cochrane Library with medical subject headings: Bone Nails, Bone Lengthening, and PRECICE and FITBONE nails. Complications were graded on severity and origin.Results - The search identified 952 articles; 116 were full text screened, and 41 were included in the final analysis. 983 segments were lengthened in 782 patients (age 8-74 years). The distribution of nails was: 214 FITBONE, 747 PRECICE, 22 either FITBONE or PRECICE. Indications for lengthening were: 208 congenital shortening, 305 acquired limb shortening, 111 short stature, 158 with unidentified etiology. We identified 332 complications (34% of segments): Type I (minimal intervention) in 11% of segments; Type II (substantial change in treatment plan) in 15% of segments; Type IIIA (failure to achieve goal) in 5% of segments; and Type IIIB (new pathology or permanent sequelae) in 3% of segments. Device and bone complications were the most frequent.Interpretation - The overall risk of complications was 1 complication for every 3 segments lengthened. In 1 of every 4 segments, complications had a major impact leading to substantial change in treatment, failure to achieve lengthening goal, introduction of a new pathology, or permanent sequelae. However, as no standardized reporting method for complications exists, the true complication rates might be different.

Aortic root distensibility after subcoronary stentless valve implantation.

BACKGROUND AND AIM OF THE STUDY: The preservation of aortic root dynamics is considered important for the durability of aortic valve bioprostheses. Stentless heart valves are believed to support physiologic biomechanics. To date, dynamic analysis has been limited to the full root prosthesis, and exclusively in the radial direction. The study aim was to investigate and compare the radial and longitudinal aortic root distensibilities of subcoronary stentless valves, and of stented and native pig valves. METHODS: Stented pericardial (Mitroflow) or stentless (Solo, Toronto SPV) valve prostheses, or native porcine valves, were investigated in 32 pigs. Postoperatively, 12 sonomicrometry crystals were placed on the aortic root in order to measure aortic root distensibility, in both radial and longitudinal directions. RESULTS: Sonomicrometry data were obtained from 23 pigs (72%). At the annular level, the native and Solo valves were significantly more distensible in a radial direction than the Mitroflow valve (p = 0.04). However, at the level of the sinotubular junction (STJ), commissures and aorta, the native valve was significantly more distensible than all of the artificial valves (p = 0.006, p = 0.006, and p = 0.02, respectively). The Solo valve exhibited less longitudinal distensibility than the Toronto SPV and Mitroflow valves. The Toronto SPV initiated a radial expansion at the STJ significantly later in the cardiac cycle than did both the Solo and native valves (p = 0.03), but showed no difference compared to the Mitroflow valve. Longitudinal expansion between the annulus and the STJ started significantly earlier for the Solo valve than for both the Toronto SPV (p = 0.03) and Mitroflow (p = 0.02) valves. CONCLUSION: The Solo valve proved to be superior in maintaining annular distensibility immediately following implantation when compared to the Mitroflow valve. The Solo valve did not, however, preserve longitudinal distensibility as well as the other investigated valves. Finally, the Solo valve appeared to provide a more physiologic aortic root expansion pattern than its prosthetic counterparts.

Leaflet opening and closing dynamics of stentless bioprostheses.

BACKGROUND AND AIM OF THE STUDY: Stiffening of the aortic root may entail asynchronous aortic leaflet movement, and result in enhanced flexion-stress in specific areas of the cusps. As stentless prostheses are more flexible than their stented counterparts, they are more likely to exhibit physiologic leaflet movements. The study aim was to compare leaflet movement dynamics in stented versus non-stented aortic valves implanted in pigs. METHODS: Aortic bioprostheses were implanted surgically into adult pigs as follows: stented Mitroflow (n = 6), stentless Solo (n = 5), and stentless Toronto SPV (n = 4). In five control animals, the native aortic valve leaflets were untouched. Postoperatively, the aortic valve was displayed by epicardial echocardiography. M-mode display of the non-coronary leaflet was applied to assess rapid valve-opening velocity (V(open)) and rapid valve-closing velocity (V(close)). RESULTS: The mean V(open) values were 29.2, 25.5, 37.8, and 31.9 cm/s, respectively, for the native, Toronto SPV, Solo, and Mitroflow valves. The mean V(close) values were 23.2, 21.9, 34.1, and 34.3 cm/s, respectively. A comparison of V(open) values showed no statistically significant difference between the valves. The Mitroflow and Solo valves yielded significantly higher V(close) values than the native and Toronto SPV valves. The Toronto SPV exhibited marked systolic leaflet folding. CONCLUSION: The stent of a bioprosthetic valve does not appear to affect leaflet velocities when compared to the stentless bioprosthetic valve. The Solo and Mitroflow valves closed more abruptly than the porcine native aortic valve; however, the Toronto SPV valve displayed diverging systolic leaflet movement patterns.

In-vivo blood velocity and velocity gradient profiles downstream of stented and stentless aortic heart valves.

BACKGROUND AND AIM OF THE STUDY: Abnormal flow conditions across aortic bioprosthetic valves may result in degenerative processes. Thus, it is important to implant biological valve prostheses with velocity profiles similar to those of native valves. The study aim was to compare blood velocity and velocity gradient profiles downstream of stented and stentless aortic valves implanted in pigs, and in native porcine valves. METHODS: Stented valve prostheses (Mitroflow, n = 7) or stentless valve prostheses (Solo, n = 5 or Toronto SPV, n = 7) were implanted into pigs; the native valve was retained in eight animals. After weaning the animals from cardiopulmonary bypass, cardiac magnetic resonance imaging was performed to determine the blood velocities and velocity gradient profiles. RESULTS: The native valves had a significantly lower peak velocity (92 +/- 26 cm/s) than the artificial valves (Solo: 247 +/- 107 cm/s; Toronto: 252 +/- 41 cm/s; Mitroflow: 229 +/- 18 cm/s). The native valves exhibited a flat velocity profile during systole, whereas the Solo valve, and especially the Toronto SPV valve, displayed more parabola-shaped velocity profiles; velocity profiles downstream of the Mitroflow valve exhibited a flat shape. The native valves had a lower mean velocity gradient at peak systole (p < 0.0001). The velocity gradient percentage above mean was lowest for the native valve (0.14 +/- 0.11; p < 0.0001), while the Mitroflow valve had a percentage of 0.57 +/- 0.09, which was lower than the Solo valve (0.69 +/- 0.12; p = 0.074), and significantly lower than the Toronto valve (0.70 +/- 0.08; p = 0.015). All valves displayed high velocity gradients adjacent to the aortic wall; in particular, the Toronto SPV which also had high velocity gradients at the center of the vessel. CONCLUSION: All of the artificial valves tested had a significantly higher mean velocity gradient and peak velocity than the native valves. However, the Mitroflow had a mean velocity and a velocity gradient percentage lower than the two stentless valves. The Solo and Mitroflow valves displayed velocity profiles most like native valves, while the Toronto valve had a more irregular asymmetric velocity profile.