Abstract
Background
Many patients with achondroplasia experience functional impairments because of rhizomelic upper extremities (proximal limb shortening). Bilateral humeral lengthening may overcome these functional limitations, but it is associated with several risks, such as radial nerve palsy and insufficient bone regeneration. Only a few studies have reported on patient satisfaction and functional outcome after humeral lengthening in patients with achondroplasia. Furthermore, the reported numbers of adverse events associated with lengthening procedures using external fixators vary widely.
Questions/purposes
(1) Does bilateral humeral lengthening with a monolateral external fixator in patients with achondroplasia reliably improve patient function and autonomy, and what proportion of patients achieved at least 8 cm of humeral lengthening? (2) What adverse events occur after bilateral humeral lengthening with monolateral external fixators?
Methods
Between 2011 and 2019, 44 patients underwent humeral lengthening at our institution. Humeral lengthening was performed in patients with severe shortening of the upper extremities and functional impairments. In humeri in which intramedullary devices were not applicable, lengthening was performed with monolateral external fixators in 40 patients. Eight patients were excluded because they underwent unilateral lengthening for etiologies other than achondroplasia, and another four patients did not fulfill the minimum study follow-up period of 2 years, leaving 28 patients with bilateral humeral lengthening to treat achondroplasia available for analysis in this retrospective study. The patients had a median (interquartile range) age of 8 years (8 to 10), and 50% (14 of 28) were girls. The median follow-up time was 6 years (4 to 8). The median humeral lengthening was 9 cm (9 to 10) with a median elongation of 73% (67% to 78%) from an initial median length of 12 cm (11 to 13). To determine whether this treatment reliably improved patient function and autonomy, surgeons retrospectively evaluated patient charts. An unvalidated retrospective patient-reported outcome measure questionnaire consisting of nine items (with answers of “yes” or “no” or a 5-point Likert scale) was administered to assess the patient’s functional improvement in activities of daily living, physical appearance, and overall satisfaction, such that 45 points was the highest possible score. The radiographic outcome was assessed on calibrated radiographs of the humerus. To ascertain the proportion of adverse events, study surgeons performed a chart review and telephone interviews. Major complications were defined as events that resulted in unplanned revision surgery, nerve injury (either temporary or permanent), refracture of the bone regenerate, or permanent functional sequelae. Minor complications were characterized as events that resolved without further surgical interventions.
Results
On our unvalidated assessment of patient function and independence, all patients reported improvement at their most recent follow-up compared with scores obtained before treatment (median [IQR] 24 [16 to 28] before surgery versus 44 [42 to 45] at latest follow-up, difference of medians 20 points, p < 0.001). A total of 89% (25 of 28) of patients achieved the desired 8 cm of lengthening in both arms. A total of 50% (14 of 28) of our patients experienced a major complication. Specifically, 39% (11 of 28) had an unplanned reoperation, 39% (11 of 28) had a radial nerve palsy, 18% (5 of 28) had a refracture of the regenerate, and 4% (1 of 28) concluded treatment with a severe limb length discrepancy. In addition, 82% (23 of 28) of our patients experienced minor complications that resolved without further surgery and did not involve radial nerve symptoms. Radial nerve palsy was observed immediately postoperatively in eight of 13 segments, and 1 to 7 days postoperatively in five of 13 segments. The treatment goal was not achieved because of radial nerve palsy in 5% (3 of 56) of lengthened segments, which occurred in 7% (2 of 28) of patients. Full functional recovery of the radial nerve was observed in all patients after a median (IQR) of 3 months (2 to 5). Refractures of bone regenerates were observed in 11% (6 of 56) of humeri in 18% (5 of 28) of patients. Of those refractures, 1 of 6 patients was treated nonsurgically with a hanging cast, while 5 of 6 patients underwent revision surgery with intramedullary rodding.
Conclusion
Most patients with achondroplasia who underwent humeral lengthening achieved the treatment goal without permanent sequelae; nonetheless, complications of treatment were common, and the road to recovery was long and often complicated, with many patients experiencing problems that were either painful (such as refracture) or bothersome (such as temporary radial nerve palsy). However, using a subjective scale, patients seemed improved after treatment; nevertheless, robust outcomes tools are not available for this condition, and so we must interpret that finding with caution. Considering our discoveries, bilateral humeral lengthening with a monolateral external fixator should only be considered in patients with severe functional impairments because of rhizomelic shortening of the upper extremities. If feasible, internal lengthening devices might be preferable, as these are generally associated with higher patient comfort and decreased complication rates compared with external fixators.
Level of Evidence
Level IV, therapeutic study.
Introduction
Achondroplasia is a skeletal dysplasia associated with rhizomelic shortening (proximal limb shortening) of the limbs and disproportionate short stature (Fig. 1). Rhizomelic upper extremities can lead to functional impairments, including difficulties in performing activities of daily living and personal hygiene [9, 12]. Although the functional benefit of lower limb lengthening is controversial [1, 13, 22], humeral lengthening might improve a patient’s function and ability to perform activities of daily living [1, 2, 11, 14, 18]. Moreover, lower limb lengthening may lead to unfavorable limb proportions, with a mismatch between the upper and lower limbs [10, 11]. This may worsen preexisting functional impairments, such as difficulties in putting on shoes [11]. Upper limb lengthening may help overcome these impediments and improve the proportion of the limbs [1, 6, 10].
Fig. 1.
A-D These images show the clinical presentation of a patient before (A-B) and after (C-D) humeral lengthening.
Intramedullary lengthening devices are associated with increased patient comfort and a lower infection risk compared with external fixators [7, 24]. However, lengthening nails are generally not recommended in patients with open physes. Furthermore, the bony dimensions of rhizomelic humeri impede intramedullary lengthening, even in most skeletally mature patients [1, 17]. Lengthening of rhizomelic humeri is therefore typically performed with external fixators [1, 6]. Only a few studies, to our knowledge, have reported patient satisfaction and functional improvement after humeral lengthening in patients with achondroplasia [1, 2, 6, 14, 18]. Moreover, adverse events associated with lengthening procedures with external fixators, particularly pin-site infection, osteomyelitis, joint contractures, as well as the occurrence of radial nerve palsy and refracture of the bone regenerate, are dreaded complications after humeral lengthening, and the proportions of patients who have experienced complications with treatment have varied widely [1, 2, 14, 18].
We therefore asked: (1) Does bilateral humeral lengthening with a monolateral external fixator in patients with achondroplasia reliably improve patient function and autonomy, and what proportion of patients achieved at least 8 cm of humeral lengthening? (2) What adverse events occur after bilateral humeral lengthening with monolateral external fixators?
Patients and Methods
Study Design and Setting
We retrospectively studied the radiographic and clinical data of patients treated with humeral lengthening in one institution between 2011 and 2019. Three pediatric orthopaedic surgeons operated on the 28 patients included in this study at our tertiary-care referral university hospital.
Patients and Indications
During the study period, we treated 44 patients for severe shortening of the upper arms. Of those, we considered patients with achondroplasia who experienced functional impairments caused by rhizomelic shortening of the humeri as potentially eligible for bilateral humeral lengthening with monolateral fixators. Based on that, 82% (36 of 44) were treated surgically, and 9% (4 of 44) were treated with intramedullary devices and excluded from the current study. During the study period, we generally used an intramedullary device when proportions of the humerus allowed the application of a lengthening nail and the lengthening was within the stroke of the device; otherwise, we used an external fixator. Of the 32 patients treated with the monolateral external fixator being studied here (Limb Reconstruction System™, Orthofix), 13% (4) did not fulfill the minimum study follow-up of 2 years, leaving 88% (28) for analysis in this retrospective study (Fig. 2). Of 28 patients included in the study, 96% (27) completed distraction and were available for evaluation. In one patient who presented with bilateral radial nerve palsy, distraction osteogenesis was not performed at all. The median (interquartile range) follow-up period was 6 years (4 to 8). The study findings are reported according to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines [25].
Fig. 2.
This STROBE diagram shows the patients who were included in this study.
Participants’ Baseline Data
Fifty percent (14 of 28) of the group were girls, and the study group had a median (IQR) age of 8 years (8 to 10) at the time of the first surgical intervention (Table 1).
Table 1.
Participants’ baseline data
| Baseline data | Total (n = 28) |
| Girls | 50% (14) |
| Number of humeri | 56 |
| Age at index surgery in years | 8 (8-10) |
| Follow-up period in years | 6 (4-8) |
Data presented as % (n) or median (IQR).
Surgical Technique
Monolateral external fixators were applied to both humeri during one operation. The mean operation time was 114.1 ± 26.5 minutes. Four stainless steel half pins were placed perpendicular to the anatomic axis, and special care was taken when applying the distal pins because of their proximity to the radial nerve (Fig. 3). The osteotomy was performed in the middle third, distal to the deltoid tuberosity. To prevent damage to the radial nerve, we performed the osteotomy under visual guidance through a skin incision of approximately 3 cm. A multiple drill-hole osteotomy of the anterior two-thirds of the cortical bone was made with a 3.2-mm or 4.5-mm drill. The osteotomy was then completed with an osteotome. The osteotomy was completed and controlled clinically by posterior angulation and outward torsion of the distal bone segment (Fig. 4). This measure was intended to protect the radial nerve. After an earlier incident at our institution where the radial nerve was fully functioning immediately after surgery, but radial nerve palsy occurred on the first postoperative day and before distraction was initiated, a Redon drain was applied in all patients treated after 2013 to prevent compression of the radial nerve by a postoperative hematoma; in total, a Redon drain was applied during 75% (42 of 56) of all operations.
Fig. 3.
A-B These drawings show the position of the four half pins of the monolateral fixator in relation to the radial nerve in a rhizomelic humerus. (A) This image is an AP view, and (B) this is a lateral view. Special caution must be exercised when applying a distal pin because of its proximity to the radial nerve.
Fig. 4.
A-H This figure demonstrates the execution of the osteotomy. These clinical photographs show that (A) a skin incision was made at the middle third of the humerus. (B) Laterally, a Langenbeck retractor was applied, rather than a Hohmann retractor, to protect the radial nerve. (C) After a multiple drill-hole osteotomy, (D) the procedure was completed with an osteotome. These radiographs show (E) a guided pin application, (F) the insertion of a Hohmann retractor laterally and a Langenbeck retractor medially before (G) the execution of the multiple drill-hole osteotomy. (H) This radiograph shows careful completion of the osteotomy with an osteotome.
Postoperative Treatment Regimen
Patients stayed in the hospital for a mean of 6 ± 2 days. Physiotherapy began on the first postoperative day, with a focus on elbow and shoulder ROM. Distraction of 1 mm daily was initiated 7 days postoperatively. If patients developed radial nerve palsy, distraction was postponed until full recovery. If necessary, reosteotomy and remounting of the external fixator were performed.
Patients were clinically and radiologically monitored at 2-week intervals during the distraction period and at 6-week intervals during the consolidation period. The median (IQR) time with an external fixator was 185 days (170 to 201). Intramedullary rods were applied immediately after fixator removal if bone regeneration was insufficient, which was the case in seven humeri.
Clinical and Radiographic Evaluation
Biplanar (AP and lateral) radiographs of the humerus were obtained for all patients preoperatively and after consolidation, every second week during the distraction period, and every 6 weeks during the consolidation period. All measurements of the initial and latest calibrated radiographs were made with the PACS® system (GE Healthcare) and the postprocessing software TraumaCad® (Brainlab).
Outcome Parameters
To determine whether this treatment reliably improved patient function and autonomy (our first research question), patient charts were retrospectively evaluated by surgeons (RR, BV) who were also involved in patient care. We administered a retrospective patient-reported outcome measure questionnaire consisting of nine items (with answers of “yes” [5 points], “no” [1 point], or a 5-point Likert scale [1-5 points]) to assess the patient’s functional improvement in activities of daily living, physical appearance, overall satisfaction, and willingness to repeat surgery, such that 45 points represented the best possible pain, function, and satisfaction achievable on this scale (Table 2). These questions were based on questionnaires used in patients with achondroplasia, including items regarding activities of daily living and functions that are likely to be impaired in patients with short arms [1, 6]. Because of a lack of validated patient-reported outcome measures for this patient group, we developed these questionnaires based on expert consensus at our institution. All 28 patients responded to the questionnaire. The secondary outcome was the percentage of patients achieving a minimum of 8 cm of lengthening in both humeri. The initial and final length of the total humerus and achieved distraction were measured on calibrated AP humeral radiographs. Another secondary outcome measure was humeral elongation, calculated with respect to the original humerus length. The duration of external fixation was acquired from hospital records. The distraction index was calculated by dividing the achieved length (in mm) by the duration of lengthening (in days). The consolidation index was determined by dividing the number of days from surgery until consolidation, divided by the length of the bone regenerate (in cm).
Table 2.
The applied unvalidated patient-reported outcome measure
| Activities | ||
| Before and after the humeral lengthening procedure, could/can you perform the following activities independently, that is, without help: | ||
| Before | After | |
| Get dressed | yes/no/NA | yes/no/NA |
| Comb/wash your hair | yes/no/NA | yes/no/NA |
| Put shoes on | yes/no/NA | yes/no/NA |
| Perform intimate hygiene / toilet visits | yes/no/NA | yes/no/NA |
| Put your hands in trouser pockets | yes/no/NA | yes/no/NA |
| Overall functional outcome | ||
| I have gained functional improvement because of the humeral lengthening. | ||
| 5 completely agree, 4 agree, 3 neither agree, nor disagree, 2 disagree, 1 completely disagree | ||
| Appearance | ||
| I am/was satisfied with the appearance of my arms before/after the humeral lengthening. | ||
| 5 completely agree, 4 agree, 3 neither agree, nor disagree, 2 disagree, 1 completely disagree | ||
| Satisfaction | ||
| I am _____________ with the result of the humeral lengthening. | ||
| 5 very satisfied, 4 satisfied, 3 neither satisfied, nor dissatisfied, 2 dissatisfied, 1 very dissatisfied | ||
| Willingness to repeat | ||
| Knowing what I know now, I would choose to undergo the humeral lengthening again. | ||
| 5 completely agree, 4 agree, 3 neither agree, nor disagree, 2 disagree, 1 completely disagree | ||
| Complications | ||
| Do you suffer from complications after the humeral lengthening, if yes, which? | ||
| free text | ||
| Were you treated elsewhere for any complications, etc., after your treatment at our institution, if yes, please specify. | ||
| free text | ||
| Comments: | ||
| free text | ||
| In order to calculate a global score of maximum 45 points: | ||
| All items regarding Activities were rated: 5 – yes, 1 – no, 3 – NA, not applicable | ||
| preoperative Functional outcome was rated: 3 neither agree, nor disagree | ||
| preoperative Satisfaction was rated: 3 neither satisfied, nor dissatisfied | ||
| preoperative Willingness to repeat was rated: 3 neither agree, nor disagree. | ||
To ascertain the proportion of adverse events that occurred, study authors (AL, JDR, RR, BV) who were also involved in the care of the 28 patients performed a chart review and telephone interviews. Major complications were defined as events that resulted in unplanned reoperation, nerve injury (either temporary or permanent), refracture of the bone regenerate, or permanent functional sequelae (limb length inequality or severe flexion contracture). Minor complications were characterized as events that resolved without further surgical interventions.
Ethical Approval
Ethical approval for this study was obtained from University Hospital Muenster, Muenster, Germany (registration number: 2019-368-f-S).
Statistical Analysis
Normal data distribution was assessed using the Shapiro-Wilk test. Descriptive statistics are presented as the mean and SD for normally distributed, continuous variables, and median with IQR for nonparametric variables. Mean values were compared using the paired t-test and dichotomous variables were compared using the Wilcoxon sign ranked test. The Pearson correlation coefficient was also calculated. The level of significance was set at p < 0.05. Statistical tests were conducted using SPSS version 27 (IBM Corp).
Results
Function, Autonomy, and Proportion of Patients Who Achieved at Least 8 cm of Lengthening
All 27 patients who ultimately underwent humeral lengthening had improvements in function and physical appearance. One patient did not achieve any lengthening. In our unvalidated assessment of patient function and independence, all patients reported improvement at most recent follow-up compared with scores obtained before treatment (median [IQR] 24 (16 to 28) before surgery versus 44 (42 to 45) out of 45 at latest follow-up, difference of medians 20 points, p < 0.001) (Fig. 5).
Fig. 5.
This figure shows the percentage of patients who were able to perform activities of daily living before (gray columns) and after (black columns) bilateral humeral lengthening. Twenty-seven of 28 patients were lengthened, and all patients reported improvements in physical appearance and function of their upper limbs on a 5-point Likert scale. Consequently, overall satisfaction and willingness to repeat were high; ap < 0.01.
Lengthening was completed in 95% (53 of 56) of lengthened bone segments in 93% (26 of 28) of our patients; 89% (25 of 28) of patients achieved lengthening of at least 8 cm in both arms. In two patients, the lengthening goal was not achieved due to complications, and one patient requested termination of distraction after lengthening of 6.5 cm due to discomfort. The median (IQR) humeral lengthening was 9 cm (9 to 10), with a median elongation of 73% (67% to 79%). The median initial humerus length was 12 cm (11 to 13). There was a correlation between humerus length and age (p < 0.001). The median distraction index was 1 mm/day (0.9 to 1.1). The median consolidation index was 20 days/cm (18 to 24) (Table 3).
Table 3.
Parameters of surgery and distraction osteogenesis
| Parameter | Findings (n = 28) |
| Patients who achieved the planned lengthening | 89% (25) |
| Initial humeral length in cm | 12 (11-13) |
| Humeral lengthening in cm | 9 (9-10) |
| Humeral elongation | 73% (67-78) |
| Time with external fixator in days | 185 (170-201) |
| Distraction index in mm/day | 1 (0.9-1.1) |
| Consolidation index in days/cm | 20 (18-24) |
| Segments that received a Redon drain | 75 (42 of 56) |
| Segments that received intramedullary rods | 13 (7 of 56) |
Data presented as % (n) or median (IQR).
Adverse Events
A total of 50% (14 of 28) of our patients experienced a major complication, defined as an event resulting in unplanned reoperation, nerve injury (either temporary or permanent), refracture of the bone regenerate, or permanent functional sequelae (limb length inequality or severe flexion contracture). Specifically, 39% (11 of 28) had an unplanned reoperation, 39% (11 of 28) had a radial nerve palsy, 18% (5 of 28) had a refracture of the regenerate at a mean of 15 ± 20 days after fixator removal, and 4% (1 of 28) concluded treatment with a severe limb length discrepancy of 5.8 cm after distraction had to be prematurely stopped on one humerus because of recurrent radial nerve palsy. In addition, 82% (23 of 28) of our patients experienced minor complications (Table 4).
Table 4.
Adverse events
| Parameter | Analyzed per segment (n = 56 segments) | Analyzed per patient (n = 28 patients) |
| Proportion with major complications (total) | 68 (38) | 50 (14) |
| Unplanned reoperation a | 32 (18) | 39 (11) |
| Reosteotomy | 16 (9) | 29 (8) |
| Intramedullary rodding due to fracture | 9 (5) | 14 (4) |
| Pin loosening | 5 (3) | 7 (2) |
| Pin breakage | 2 (1) | 4 (1) |
| Temporary radial nerve palsy | 23 (13) | 39 (11) |
| Immediately postoperatively | 62 (8 of 13) | 55 (6 of 11) |
| 1-7 days postoperatively | 38 (5 of 13) | 45 (5 of 11) |
| 0/5 MRCS b | 69 (9 of 13) | 73 (8 of 11) |
| 1/5 MRCS b | 23 (3 of 13) | 18 (2 of 11) |
| 3/5 MRCS b | 8 (1 of 13) | 9 (1 of 11) |
| Refracture of the regenerate | 11 (6) | 18 (5) |
| Permanent functional sequela: limb length inequality | 2 (1) | 4 (1) |
| Proportion with minor complications (total) | 82 (46) | 82 (23) |
| Pin tract infection | 21 (12) | 36 (10) |
| Temporary flexion contracture | 61 (34) | 68 (19) |
| Of more than 50° | 12 (4 of 34) | 16 (3 of 19) |
Data presented as % (n).
In some patients, one segment/humerus required two reoperations
Muscle strength according to MRCS; 0/5: no contraction; 1/5: flicker or trace contraction; 3/5: active movement against gravity; MRCS = Medical Research Council Scale.
No premature or delayed bone union was observed. Regarding refractures, there was no correlation between the refracture proportion and the amount of lengthening (Pearson correlation coefficient = 0.117; p = 0.39). One patient with a refracture was treated nonoperatively with immobilization in a hanging cast for 3 weeks, and four patients (one of whom presented with bilateral refracture) underwent surgery for intramedullary rodding. The occurrence of radial nerve palsy resulted in a reosteotomy in 29% (8 of 28) of our patients, which delayed distraction initiation for a median (IQR) of 3 months (2 to 11). Full functional recovery of the radial nerve was observed in all patients after a median of 3 months (2 to 5). We found no correlation between the initial humerus length and proportion of radial nerve palsy (Pearson correlation coefficient = 0.183; p = 0.18) and observed a negative correlation between radial nerve palsy and the relative elongation distance (Pearson correlation coefficient = -0.285; p = 0.04). Furthermore, the occurrence of radial nerve palsy was not reduced by application of a Redon drain (Pearson correlation coefficient = -0.116; p = 0.39).
Discussion
Although lengthening procedures of the lower extremities in patients with achondroplasia are controversial because the potential functional improvements have not been documented thoroughly [1, 13, 22], humeral lengthening can improve the function and autonomy of patients with rhizomelic shortening of the upper extremities [1-3, 11]. However, few studies that we know of have evaluated functional improvement and adverse events after humeral lengthening procedures, particularly the frequency of radial nerve palsy and refracture of bone regenerates, and the reported results vary widely [1, 2, 7, 14, 18]. In the present study, most patients achieved the treatment goal without permanent sequelae and reported an improvement of function; however, our findings should be interpreted with care because of the lack of a validated outcomes tool. Moreover, treatment complications were common. Thus, bilateral humeral lengthening with a monolateral external fixator should only be considered in patients with severe functional impairments caused by rhizomelic shortening of the upper extremities, and the lengthening procedure should preferably be performed at a center with a high level of expertise in managing achondroplasia.
Limitations
Although the study design is homogenous in terms of the operative approach and applied monolateral external fixation device, the age at the time of the first surgery differed and limited comparability. This should be taken into consideration when evaluating our findings, as different age groups might experience different complications. A prospective, comparative study design is needed to clearly identify potential age-related risk factors. Furthermore, some selection bias likely was present because not all patients with achondroplasia who were treated at our department underwent humeral lengthening, presumably because some felt only minimally affected by their condition. Moreover, patients who presented sufficient bony diameters of the humerus were treated with intramedullary lengthening devices rather than external fixators, which are presumably associated with a higher complication rate.
In addition, assessment bias cannot be ruled out. First, the patients were treated and followed by the same physicians who assessed and interpreted the data in the present study; second, functional information, such as joint ROM, was retrospectively acquired from hospital records by the treating surgeons, thus the apparent benefits of this surgical intervention may have been overestimated. In patients with achondroplasia who undergo humeral lengthening, a standardized evaluation of the functional outcome is difficult because there are no validated patient-reported outcome measures for this patient group regarding arm function [1, 2, 6, 8]. Although some authors have used the DASH score [2], this outcome measure has not been validated in patients with achondroplasia, and it is predominantly used in posttraumatic evaluations [4]. Other authors have used their own unvalidated questionnaire to evaluate the outcome of humeral lengthening in children with achondroplasia [1, 6]. The heterogeneity and lack of a validated patient-reported outcome measure limited comparisons of the functional outcome in the present study. A standardized questionnaire about functional outcomes and patient satisfaction with humeral lengthening would help to improve the comparability with various studies. Although the questionnaire we adopted was unvalidated, we believe it allowed us to adequately evaluate the functional outcome and patient satisfaction after humeral lengthening. Nevertheless, the floor and ceiling effects of the questionnaire must be studied further, and unvalidated tools like the one we used tend to inflate the apparent benefits of treatment; readers should consider that as they evaluate our findings, and we hope others will seek to confirm or refute our discoveries as presented here.
Finally, the use of statistics best suited for unpaired data may be inappropriate for assessing bilateral lengthening procedures. Nonetheless, most of the provided data are only based on descriptive statistics. Therefore, although two treatments per patient were pooled, this does not hamper the external validity of the presented data.
Function, Autonomy, and Proportion of Patients Who Achieved at least 8 cm of Lengthening
Using our unvalidated outcomes tool, we found consistent improvements in patients treated with bilateral humeral lengthening; obviously using a validated tool would have been preferable, but to our knowledge, no such tool exists. Our findings support the supposition that humeral lengthening can enable patients with achondroplasia to perform activities of daily living more independently and thus achieve overall greater patient autonomy. However, it should be noted that our unvalidated outcome tool depends on highly subjective patient-reported outcome, thus our findings should be interpreted carefully. Nevertheless, in a patient cohort like our own, Arenas-Miquelez et al. [1] reported 50 humeral lengthening procedures with a mean humeral lengthening of 8.8 cm (range 5 to 10.5). Consistent with our own results, all their patients reported functional improvement, and 22 of 25 patients became autonomous regarding personal hygiene and putting on shoes. Another study evaluated 110 lengthening procedures of the humerus with a mean of 9.6 cm (range 3.9 to 13.9) of humeral lengthening [6]. They reported an improvement in performing activities of daily living in all patients. Balci et al. [2] evaluated 36 humeral lengthening procedures in patients with achondroplasia with a median lengthening of 8.0 cm (IQR 7.0 to 8.0 cm). They stated that “preparing a meal, placing an object over the head, washing the back and hair, […] and feeling more capable of doing daily activities” were the most improved functions. They suggested that a mean lengthening of 60% was required to achieve independent perineal hygiene.
Adverse Events
Adverse events were extremely common in this report, and 50% (14 of 28) of our patients had a major complication, defined as an event resulting in unplanned reoperation, nerve injury (either temporary or permanent), refracture of the bone regenerate, or permanent functional sequelae (limb length inequality or severe flexion contracture). It is difficult to compare our results with others, particularly because of heterogeneity in cohort sizes, patient ages, amount of lengthening, and surgical techniques. However, the proportion of patients experiencing a radial neve palsy observed in the present study was considerably higher than the reported proportions of radial neve palsy, which have been in the range of 2% to 8% for humeral lengthening procedures that were performed with monolateral external fixators in patients with achondroplasia [1, 2, 6, 15, 23] (Table 5). Lee et al. [14] stated that damage of the radial nerve might be related to the osteotomy, application of an external fixator, or the distraction process. The surgical technique used in the present study does not seem to differ from the techniques described by other authors. In all humeri, the osteotomy was performed at the middle third of the humerus and under visual guidance, as recommended [1, 8, 10]. Translation of the bone after osteotomy (either to verify that the osteotomy has been completed or to achieve additional deformity correction), which may result in neuropraxia due to strain of the radial nerve, was avoided. However, we speculate that there might be a correlation between the median age at the time of the first surgical intervention (and, consequently, the median initial humerus length) in our study cohort and the incidence of radial nerve palsy. In the present study, the median age at the time of the first surgery was 8 years and the median initial humerus length was 12 cm. We found a correlation between age and humerus length. Other studies, which reported a much lower frequency of radial nerve palsy, included patients with a median age from 10 to 17 years [2], and a median initial humerus length ranging from 13.5 to 16.7 cm [2]. A shorter humerus might imply that there are altered anatomic conditions with compressed soft tissues. In extremely short rhizomelic humeri, the application of the more proximal of the two distal pins might thus entail an increased risk for radial nerve injury [5] and might have also been a potential cause for the increased frequency of radial nerve palsy in our young patient cohort. We did not observe any complications during osteotomy or pin application. Moreover, a possible correlation between the initial humerus length and risk of intraoperative injury of the radial nerve remains difficult to evaluate.
Table 5.
Comparison of radial nerve palsy and refracture proportions in patients with achondroplasia undergoing humeral lengthening with monolateral external fixators
| Arenas-Miquelez et al. [1] (n = 50) | Balci et al. [2] (n = 36) | Ginebreda et al. [6] (n = 110) | Malot et al. [15] (n = 34) | Shadi et al. [23] (n = 16) | Current study (n = 56) | |
| Radial nerve palsy | 2 (1) | 8 (3) | 2 (2) | 3 (1) | 6 (1) | 23 (13) |
| Refracture | 0 (0) | 11 (4) | 8 (9) | 6 (2) | 6 (1) | 11 (6) |
Data presented as % (n), referring to lengthened segments.
Nevertheless, neuropraxia is more likely associated with surgical technique than with the lengthening process. In the present study, more than half of all patients who developed a radial nerve palsy had it diagnosed immediately postoperatively, and only two occurred during the distraction period. Hosny [8] mentioned that a hematoma might explain the occurrence of radial nerve neuropraxia immediately postoperatively. This might be prevented by applying a Redon drain. However, we could not find a correlation between the application of a Redon drain and the occurrence of radial nerve palsy.
Presumably, regarding the occurrence of radial nerve palsy, it might be safer to perform the lengthening procedure only in adolescent or skeletally mature patients, which might also allow for an intramedullary lengthening nail because the humerus has an increased length and diameter. However, we believe that performing humeral lengthening during childhood is more likely to help patients lead a more independent life and will thus contribute to an improved quality of life. Overall, the ideal timing of the lengthening procedure remains unknown. In patients with only minor functional impairments, we recommend delaying treatment until adolescence, with an increased humerus length and a presumably decreased risk of radial nerve palsy. In children with major impairments owing to shortening of the upper extremities, however, we believe that humeral lengthening can improve the patient's quality of life because it can provide improved function, which justifies the potentially increased risk of radial nerve palsy.
The occurrence of bone regenerate refracture is difficult to predict. The reported frequencies range between 0 and 11% (Table 5) [1, 2, 6], which is comparable with the 11% proportion we saw in our present study. More lengthening might lead to higher likelihoods of refractures; however, we could not find a correlation. A longer external fixation time or application of intramedullary rods after fixator removal could diminish the refracture risk. Nevertheless, other than in femoral lengthening [21], the retrograde insertion of intramedullary rods in humeri is associated with an increased risk of approach-related nerve damage [19]. Additionally, intramedullary rod insertion requires another surgical intervention for removal. It should thus only be considered if there is radiologically insufficient bone regeneration. Protective bracing for 6 weeks after fixator removal, as proposed by Hosny [8], requires immobilization of both arms for several weeks and thus results in a markedly impaired quality of life. We recommend that patients should refrain from sports and lifting loads of more than 5 kg for 3 months after removal of the external fixators to prevent refractures of the bone regenerate.
Temporary flexion contracture of the elbow is frequently encountered during humeral distraction osteogenesis, but full ROM is generally regained after treatment. We suspect that this might be related to the high soft tissue compliance of patients with achondroplasia, who usually have soft tissue and ligament laxity [11]. However, based on assessment bias, lack of full ROM might be underreported both in our study and in other studies [2, 10, 20]. Nevertheless, loss of up to 30° of elbow extension is believed to not greatly affect function [16]; Lee et al. [14] even stated that painless flexion contracture of less than 50° should not lead to premature termination of the lengthening procedure.
Conclusion
Bilateral humeral lengthening in patients with achondroplasia may improve a patient’s self-care and independence. Most patients in this small series achieved the treatment goal without permanent sequelae; nonetheless, the road to recovery is often long and complicated, with many patients experiencing problems that can be painful (such as refracture) or bothersome (such as temporary radial nerve palsy). We thus recommend that bilateral humeral lengthening should be performed at centers with a high level of expertise in managing achondroplasia, as early recognition of adverse events and early treatment are crucial to ensuring successful treatment. Future prospective studies might be helpful to further evaluate which patients are at increased risk for adverse events—in particular, radial nerve palsy—when they undergo humeral lengthening. Furthermore, the establishment of a validated assessment tool for functional outcome after limb lengthening in achondroplasia will be important to improve comparability and reliability of future studies.
Acknowledgments
We thank all our patients and their families for their continuous support of our work and acknowledge the physicians, especially Dr. Frank Schiedel and Dr. Jan Niklas Broeking, as well as the nurses and support staff who contributed to the treatment of the patients included in this study.
Footnotes
Three authors (JDR, RR, BV) certify receipt of personal payments or benefits during the study period, in an amount of less than USD 10,000 from Orthofix.
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research ® editors and board members are on file with the publication and can be viewed on request.
Clinical Orthopaedics and Related Research ® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use.
Ethical approval for this study was obtained from University Hospital Muenster, Muenster, Germany (registration number: 2019-368-f-S).
This work was performed at University Hospital Muenster, Muenster, Germany.
Contributor Information
Jan Duedal Rölfing, Email: jan.roelfing@clin.au.dk.
Georg Gosheger, Email: georg.gosheger@ukmuenster.de.
Gregor Toporowski, Email: gregor.toporowski@ukmuenster.de.
Adrien Frommer, Email: adrien.frommer@ukmuenster.de.
Robert Roedl, Email: roedlr@ukmuenster.de.
Bjoern Vogt, Email: bjoern.vogt@ukmuenster.de.
References
- 1. Arenas-Miquelez A, Arbeloa-Gutierrez L, Amaya M, Vazquez B, De Pablos Fernandez J. Upper limb lengthening in achondroplasia using unilateral external fixation. J Pediatr Orthop. 2021;41:e328-e336. [DOI] [PubMed] [Google Scholar]
- 2. Balci HI, Kocaoglu M, Sen C, et al. Bilateral humeral lengthening in achondroplasia with unilateral external fixators: is it safe and does it improve daily life? Bone Joint J. 2015;97:1577-1581. [DOI] [PubMed] [Google Scholar]
- 3. Batibay SG, Balci HI, Bayram S, et al. Quality of life evaluation following limb lengthening surgery in patients with achondroplasia. Indian J Orthop. 2020;54:39-46. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4. Beaton DE, Wright JG, Katz JN, Upper Extremity Collaborative G. Development of the QuickDASH: comparison of three item-reduction approaches. J Bone Joint Surg Am. 2005;87:1038-1046. [DOI] [PubMed] [Google Scholar]
- 5. Clement H, Pichler W, Tesch NP, Heidari N, Grechenig W. Anatomical basis of the risk of radial nerve injury related to the technique of external fixation applied to the distal humerus. Surg Radiol Anat. 2010;32:221-224. [DOI] [PubMed] [Google Scholar]
- 6. Ginebreda I, Campillo-Recio D, Cardenas C, et al. Surgical technique and outcomes for bilateral humeral lengthening for achondroplasia: 26-year experience. Musculoskelet Surg. 2019;103:257-262. [DOI] [PubMed] [Google Scholar]
- 7. Hammouda AI, Standard SC, Robert Rozbruch S, Herzenberg JE. Humeral lengthening with the PRECICE magnetic lengthening nail. HSS J. 2017;13:217-223. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Hosny GA. Humeral lengthening and deformity correction. J Child Orthop. 2016;10:585-592. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9. Ireland PJ, McGill J, Zankl A, et al. Functional performance in young Australian children with achondroplasia. Dev Med Child Neurol. 2011;53:944-950. [DOI] [PubMed] [Google Scholar]
- 10. Kashiwagi N, Suzuki S, Seto Y, Futami T. Bilateral humeral lengthening in achondroplasia. Clin Orthop Relat Res. 2001;391:251-257. [DOI] [PubMed] [Google Scholar]
- 11. Kim SJ, Agashe MV, Song SH, et al. Comparison between upper and lower limb lengthening in patients with achondroplasia: a retrospective study. J Bone Joint Surg Br. 2012;94:128-133. [DOI] [PubMed] [Google Scholar]
- 12. Kopits SE. Orthopedic complications of dwarfism. Clin Orthop Relat Res. 1976;114:153-179. [PubMed] [Google Scholar]
- 13. Lavini F, Renzi-Brivio L, de Bastiani G. Psychologic, vascular, and physiologic aspects of lower limb lengthening in achondroplastics. Clin Orthop Relat Res. 1990;250:138-142. [PubMed] [Google Scholar]
- 14. Lee FY, Schoeb JS, Yu J, Christiansen BD, Dick HM. Operative lengthening of the humerus: indications, benefits, and complications. J Pediatr Orthop. 2005;25:613-616. [DOI] [PubMed] [Google Scholar]
- 15. Malot R, Park KW, Song SH, Kwon HN, Song HR. Role of hybrid monolateral fixators in managing humeral length and deformity correction. Acta Orthop. 2013;84:280-285. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16. Morrey BF, Askew LJ, Chao EY. A biomechanical study of normal functional elbow motion. J Bone Joint Surg Am. 1981;63:872-877. [PubMed] [Google Scholar]
- 17. Morrison SG, Georgiadis AG, Dahl MT. Lengthening of the humerus using a motorized lengthening nail: a retrospective comparative series. J Pediatr Orthop. 2020;40:e479-e486. [DOI] [PubMed] [Google Scholar]
- 18. Pawar AY, McCoy TH, Jr, Fragomen AT, Rozbruch SR. Does humeral lengthening with a monolateral frame improve function? Clin Orthop Relat Res. 2013;471:277-283. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19. Pogorelic Z, Kadic S, Milunovic KP, et al. Flexible intramedullary nailing for treatment of proximal humeral and humeral shaft fractures in children: a retrospective series of 118 cases. Orthop Traumatol Surg Res. 2017;103:765-770. [DOI] [PubMed] [Google Scholar]
- 20. Ruan H, Zhu Y, Liu S, Kang Q. Humeral lengthening and proximal deformity correction with monorail external fixator in young adults. Int Orthop. 2018;42:1107-1111. [DOI] [PubMed] [Google Scholar]
- 21. Schiedel F, Elsner U, Gosheger G, Vogt B, Rodl R. Prophylactic titanium elastic nailing (TEN) following femoral lengthening (lengthening then rodding) with one or two nails reduces the risk for secondary interventions after regenerate fractures: a cohort study in monolateral vs. bilateral lengthening procedures. BMC Musculoskelet Disord. 2013;14:302. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22. Schiedel F, Rodl R. Lower limb lengthening in patients with disproportionate short stature with achondroplasia: a systematic review of the last 20 years. Disabil Rehabil. 2012;34:982-987. [DOI] [PubMed] [Google Scholar]
- 23. Shadi M, Musielak B, Koczewski P, Janusz P. Humeral lengthening in patients with achondroplasia and in patients with post-septic shortening: comparison of procedure efficiency and safety. Int Orthop. 2018;42:419-426. [DOI] [PubMed] [Google Scholar]
- 24. Sheridan GA, Falk DP, Fragomen AT, Rozbruch SR. Motorized internal limb-lengthening (MILL) techniques are superior to alternative limb-lengthening techniques. JB JS Open Access. 2020;5:e20.00115. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25. von Elm E, Altman DG, Egger M, et al. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Epidemiology. 2007;18:800-804. [DOI] [PubMed] [Google Scholar]