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Abstract

Purpose

Although clavicular fracture nonunion is uncommon, it can lead to pain and alterations in clavicular length, potentially affecting shoulder function. This study investigated the relationship between clavicular length changes and clinical outcomes following nonunion treatment.

Methods

This retrospective study included 30 patients who underwent surgical treatment for clavicular nonunion between January 2013 and December 2021. The clavicle length was measured pre- and postoperatively using anteroposterior radiography. Clinical evaluation involved measuring pre- and postoperative outcomes using the Constant-Murley scoring system. Subgroup analysis was performed by dividing patients into two groups based on the median clavicle length difference.

Results

The mean age was 45.8 years, and the mean follow-up period was 5.8 years. Osseous union was achieved in all cases. The mean clavicle length difference was 5.57 ± 8.45 mm, indicating a predominance of shortening in the affected clavicle. Functional outcomes demonstrated significant improvement following surgical intervention (p < .001). A weak negative correlation (r = −0.19, p = .296) was observed between clavicle length difference and score improvement. Subgroup analysis revealed no statistically significant differences in clinical outcomes between the low and high length difference groups (p = .757).

Conclusion

Surgical treatment of clavicular nonunion results in significant functional improvement. However, the extent of clavicular length change does not appear to be a major determinant of clinical outcomes. This finding has important implications for surgical planning and patient management in cases of clavicular nonunion.

Keywords

clavicular nonunion clavicular length clinical outcomes shoulder function functional assessment constant-murley score retrospective study

Background

The clavicle serves as a crucial anatomical structure that connects the upper limb to the trunk, preserves the normal breadth of the shoulder, and acts as a fulcrum for shoulder stability during movement.^1–3 Fractures of the clavicle constitute 2%–5% of all adult fractures and typically result from falling onto an extended arm or direct trauma.^4–8 Clavicular fracture nonunion is an uncommon complication, occurring in approximately 0.9%–4% of cases.^9–12 Although nonunion symptoms are infrequent, discomfort and alterations in clavicular length may lead to biomechanical issues that affect shoulder function.

The impact of clavicular lengthening or shortening on post-fracture clinical outcomes remains a subject of ongoing debate.^{1–3,9,13–18} From a biomechanical perspective, changes in the shoulder lever arm are known to disrupt thoracohumeral muscle balance and affect scapular orientation and glenohumeral joint positioning, thereby potentially influencing shoulder function. Nevertheless, several studies have suggested minimal clinical significance of these changes.^{13,15,16,19–22}

The primary aim of treating painful nonunions is to alleviate discomfort by ensuring osteogenic stability, with most cases warranting surgical intervention.¹² Restoring the original clavicular length during surgery could theoretically be beneficial due to the biomechanical changes caused by altered clavicular length.^1,3 However, this may prove challenging due to variations in nonunion type and the potential need for bone grafting. In particular, when bone grafting is necessary, determining the extent of grafting required to restore length can be problematic.

Limited research has explored the clinical importance of clavicular length restoration for functional recovery in nonunion treatments. This study is the first to perform subgroup analysis based on clavicular length differences in nonunion treatment, providing novel insights into surgical priorities. Consequently, this study investigated the relationship between clavicular length changes and clinical outcomes following nonunion treatment with long-term follow-up to serve as a reference for surgical planning.

Methods

Patient selection and criteria

Patients who underwent surgical treatment for clavicular nonunion between January 2013 and December 2021 were included in this study. Pediatric patients with open growth plates were excluded to ensure skeletal maturity. To optimize functional evaluation, cases with previous surgical treatment of the upper limb involving clavicle fractures or cases where concurrent upper limb pathology existed were excluded.

Nonunion was defined as at least 6 months after the initial injury with no visible healing process in the preceding 3 months, indicating absence of evidence of bony union and clinical complaints of persistent pain. Patients who had been followed up for at least 3 years were included to ensure adequate assessment of long-term outcomes. Patients who received other treatments or developed diseases affecting the upper limb, including both shoulder joints, during the follow-up period were excluded from the analysis.

Of the initial 61 patients identified with clavicular nonunion, 31 were excluded due to the following reasons: 12 patients were lost to follow-up, 9 had incomplete radiological or clinical data, and 10 had comorbid conditions involving the upper limb or underwent previous surgical treatment that precluded accurate functional evaluation.

Surgical treatment method

In all cases, plate fixation combined with bone grafting was employed for surgical treatment. For hypertrophic nonunion, the procedure involved removing fibrous tissue from the nonunion site, re-establishing the medullary canal, utilizing surrounding callus or iliac cancellous bone for grafting, and securing fixation with a plate. Patients with atrophic or oligotrophic nonunion underwent a similar process, with the addition of an iliac strut bone graft before plate fixation.

The graft was designed to match the affected clavicle length with that of the contralateral unaffected side, as determined preoperatively through radiographic measurement. Compression was applied via the plate to ensure tight insertion of the bone graft at the fracture site. When necessary, an additional small plate was used for dual plate fixation to enhance stability. Fixation was achieved using a pre-contoured locking compression plate (3.5-mm LCP Superior Clavicle Plate; DePuy Synthes, Zuchwil, Switzerland) and, when needed, a mini-plate (2.7-mm mini-hand foot plate; DePuy Synthes, Zuchwil, Switzerland).

Data collection and analysis

This study employed a retrospective chart review methodology. The researchers examined patients’ medical and radiological records comprehensively. The clavicle length was measured pre- and postoperatively using anteroposterior (AP) radiography by measuring the line connecting the medial and lateral ends of the clavicle (Figure 1).

Figure 1.

Clavicular length measurement method. On an anteroposterior radiograph of the clavicle, the length is defined as the line connecting the middle of the medial border with the most lateral edge.

According to previous findings, AP and craniocaudal views provide more accurate assessments of clavicular length change than the caudocranial view.²³ Thus, this study utilized the AP view for consistent measurement. Two observers (a surgeon and a resident) performed the measurements independently to assess inter-observer reliability and ensure measurement accuracy. Union was defined as complete consolidation in three of the four cortices on radiographic evaluation.

Clinical evaluation involved measuring pre- and postoperative outcomes at the final follow-up using the Constant-Murley scoring system, which comprehensively evaluates pain, activities of daily living, range of motion, and muscle strength.²⁴ A subgroup analysis was conducted by dividing patients into two groups based on the median clavicle length difference to compare improvements in Constant-Murley scores between groups. The median length difference of 5.57 mm was used to stratify patients into low and high difference groups.

Statistical analysis

SPSS version 20.0 (IBM Corp., Armonk, NY, USA) was used for all statistical analyses. Continuous variables are reported as mean ± standard deviation, while categorical variables are presented as frequencies and percentages. Pre- and postoperative outcomes were compared using paired t-tests to assess the significance of functional improvement. Subgroup analyses were performed using independent t-tests to compare outcomes between groups.

Pearson’s correlation test was used to examine the relationship between clavicular length changes and clinical outcomes following nonunion treatment. The reliability of clavicle length measurements was assessed using the Intraclass Correlation Coefficient (ICC) with a two-way mixed-effects model for absolute agreement (ICC(3,1)) to determine inter-observer reliability. Statistical significance was set at p < .05 for all analyses.

Results

Patient demographics and follow-up

Of the 61 patients with clavicular nonunion initially identified, 30 patients met the inclusion criteria and were selected for analysis. The mean age was 45.8 years (range: 17–78 years), and the cohort comprised 18 males (60%) and 12 females (40%). The mean follow-up period was 5.8 years (range: 3–12 years), ensuring adequate long-term assessment of outcomes. Osseous union was successfully achieved in all cases (100% union rate).

Measurement reliability

Inter-observer reliability was assessed for clavicle length measurements using the Intraclass Correlation Coefficient (ICC). For non-fracture side measurements, the ICC(3,1) was 0.938, indicating excellent agreement between observers. Similarly, fracture side length measurements demonstrated an ICC(3,1) of 0.938, confirming high reliability and consistency of the measurement technique.

Clavicular length analysis

The mean clavicle length on the non-fracture side was 150.74 ± 12.38 mm, while the mean length on the fracture side was 145.17 ± 14.36 mm. This resulted in a mean length difference of 5.57 ± 8.45 mm, indicating a predominance of shortening in the affected clavicle compared to the contralateral side.

Functional outcomes

Functional outcomes assessed using the Constant-Murley score demonstrated significant improvement following surgical intervention. The mean preoperative score was 78.30 ± 3.16, which increased to 90.52 ± 3.25 postoperatively. The mean improvement in the Constant-Murley score was 12.22 points. A paired t-test performed to evaluate the statistical significance of this change revealed a highly significant improvement (p < .001), indicating substantial functional recovery following surgical treatment.

Correlation analysis

A weak negative correlation (r = −0.19, p = .296) was observed between clavicle length difference and score improvement, suggesting that changes in length might not directly influence functional outcomes (Figure 2).

Figure 2.

Correlation between length difference and score improvement. Pearson’s correlation test revealed a weak negative correlation (r = −0.19, p = .296) between clavicle length difference and score improvement, suggesting that changes in length might not directly influence functional outcomes. X-axis labels indicate: positive values = normal side longer, negative values = normal side shorter.

This finding indicates that the extent of clavicular length change does not significantly correlate with the degree of functional improvement achieved through surgical intervention.

Subgroup analysis

To further investigate the impact of clavicular length differences on clinical outcomes, patients were stratified into two groups based on the median length difference. The Low Length Difference Group (≤median, n = 15) had a mean score improvement of 12.06 ± 1.95, while the High Length Difference Group (>median, n = 15) showed a mean score improvement of 12.40 ± 3.91.

An independent t-test was conducted to compare the mean score improvement between the two groups. The results indicated no statistically significant differences in clinical outcomes (t = −0.31, p = .757), further supporting the finding that clavicular length differences do not significantly impact functional recovery (Figure 3).

Figure 3.

Score improvement in low versus high length difference groups. An independent t-test was conducted to compare the mean score improvement between the two groups. The results indicated no statistically significant differences in clinical outcomes (t = −0.31, p = .757).

A summary of all results is presented in Table 1.

Table 1.

Summary of patient demographics and clinical outcomes.

Parameter	Value
Patient demographics
Number of patients	30
Mean age (years)	45.8 (17 years to 78 years)
Sex (male/female)	18 (60%)/12 (40%)
Mean follow-up period (years)	5.8 (3 years to 12 years)
Osseous union rate	100%
Clavicle length measurements
Non-fracture side (mm)	150.74 ± 12.38
Fracture side (mm)	145.17 ± 14.36
Mean length difference (mm)	5.57 ± 8.45
Constant-murley scores
Preoperative score	78.30 ± 3.16
Postoperative score	90.52 ± 3.25
Mean score improvement	12.22 (p < .001)
Subgroup analysis
Low length difference group (n = 15)	12.06 ± 1.95
High length difference group (n = 15)	12.40 ± 3.91
p-value (independent t-test)	0.757

Complications

No major complications such as deep wound infection, implant failure, or neurological deficits were observed. One patient experienced superficial wound infection, which resolved with oral antibiotics. There were no cases of delayed union or nonunion. Implant removal was performed in 7 out of 30 patients (23.3%) due to implant-related irritation, not due to implant failure.

Discussion

The causes of nonunion after clavicular fracture are multifactorial and include the degree of initial trauma, extent of bone fragment displacement, inadequate fixation, and periosteal damage during open reduction surgery.^9,10,12 Symptoms typically include persistent pain and alterations in shoulder joint function.^1,3,18 When these symptoms occur, surgical intervention with rigid fixation and bone grafting becomes the treatment of choice.

Pain and dysfunction may persist even after achieving bone union through surgery. This may be attributed to changes in clavicular length caused by shortening or lengthening during the healing process. Therefore, understanding whether changes in clavicular length affect clinical outcomes is crucial for determining the importance of length restoration during surgical intervention.

Several biomechanical studies have investigated the potential impact of shortening on clinical outcomes, with some evidence suggesting that severe shortening affects functional results.^1–3,6,18 While Lazarides and Zafiropoulos reported poor outcomes with shortening >14–18 mm, our study’s mean shortening of 5.57 mm may be below the threshold for significant kinematic changes, explaining the lack of correlation.⁶ Additionally, a systematic review of four randomized controlled studies and 12 non-randomized retrospective comparative studies found no significant association between clavicle shortening and shoulder outcome scores in nonsurgically treated fractures.¹⁵

However, it remains unclear whether these findings apply equally to patients with acute fractures and those with established nonunion. Shortening of the clavicle can theoretically affect clinical outcomes only when it results in substantial changes in shoulder kinematics. Stegeman et al. demonstrated that patients with non-surgically treated clavicle fractures had kinematic changes compared with their uninjured contralateral shoulder, with an average clavicle shortening of 25 mm observed in these patients.²⁵ This degree of shortening was more significant than that observed in the current patient cohort.

In our study, while clavicle shortening exceeding 19 mm was detected in three cases, no instances of scapular dyskinesis were clinically identified. Therefore, it is possible that the actual correlation between clavicular shortening and functional outcomes was masked due to the relatively small degree of shortening in our patient series. However, other studies have demonstrated that shortening has no significant effect on clinical outcomes.^14–16

Previous studies have primarily focused on shortening that occurred after initial fracture treatment, and studies specifically examining length changes after nonunion treatment are limited.^12,13 Hollo et al. reported results and length changes after plate fixation and cortical bone graft for clavicle nonunion and found that length change did not significantly affect clinical outcomes.¹³ Our study similarly investigated the relationship between changes in clavicular length and clinical outcomes following surgical treatment for clavicular nonunion.

The results of our study demonstrated significant improvement in functional outcomes post-surgery, as measured by the Constant-Murley score. However, the correlation between clavicular length change and clinical improvement was weak and not statistically significant. The mean clavicular length difference of 5.57 ± 8.45 mm between the fractured and non-fractured sides indicates a tendency towards shortening in the affected clavicle, which aligns with findings from previous studies reporting clavicular shortening after fractures.^{6,15,19,26,27}

The substantial improvement in Constant-Murley scores from 78.30 ± 3.16 preoperatively to 90.52 ± 3.25 postoperatively (p < .001) suggests that surgical intervention for clavicular nonunion is highly effective in improving shoulder function. This improvement likely results from restoration of clavicular stability and resolution of the nonunion, rather than from changes in clavicular length per se.

The weak negative correlation (r = −0.19, p = .296) between clavicular length difference and score improvement indicates that the extent of length change may not be a critical factor in determining functional outcomes. This finding is consistent with other studies reporting no significant association between changes in clavicular length and clinical results,^13–16,19 challenging the notion that restoring exact clavicular length is necessary for achieving optimal clinical outcomes.

Furthermore, subgroup analysis comparing patients with high and low length differences showed no significant difference in score improvement between groups. This result provides additional support for the concept that minor variations in clavicular length may not substantially impact functional outcomes in nonunion treatments.

Clinical implications

These findings have several important clinical implications for surgical planning and patient management. Although surgeons often strive to restore the original clavicular length during nonunion treatment, our results suggest that achieving exact length restoration may not be crucial for functional improvement. This could potentially simplify surgical decision-making, especially in cases where extensive bone grafting would be required to achieve anatomical length restoration.

The results also suggest that surgical efforts should focus primarily on achieving stable union rather than pursuing precise anatomical reconstruction of clavicular length. Surgeons may prioritize rigid fixation and bone grafting over extensive length restoration, potentially reducing operative time and complications. This approach may reduce operative complexity and potentially decrease complications associated with extensive bone grafting procedures.

Study limitations

This study has several limitations that should be acknowledged. The retrospective design and relatively small sample size may limit the generalizability of the results to broader patient populations. Selection bias may have occurred due to the exclusion of patients with concurrent upper limb pathologies, potentially limiting generalizability. Additionally, the use of two-dimensional radiographs for length measurements may not capture the full complexity of three-dimensional clavicular deformities.²⁸ Advanced imaging techniques such as computed tomography or magnetic resonance imaging might provide more accurate assessment of clavicular anatomy and length changes.

Navigation systems or intraoperative ultrasound guidance for more accurate length measurement during surgery could also be considered for future studies.¹³ Additionally, longer-term follow-up studies with larger sample sizes and three-dimensional imaging techniques could provide further insights into the biomechanical and clinical implications of clavicular length changes in nonunion treatments.

Despite these limitations, this study represents the first analysis to examine subgroups based on clavicular length differences in nonunion treatment and provides valuable indicators for clinical decision-making in nonunion management. The findings contribute important evidence to guide surgical approaches in clavicular nonunion treatment, emphasizing the importance of achieving union and stability over exact length restoration.

Conclusions

Surgical treatment of clavicular nonunion results in significant functional improvement as measured by validated outcome scores. However, the extent of clavicular length change does not appear to be a major determinant of clinical outcomes. This finding has important implications for surgical planning and patient management in cases of clavicular nonunion, suggesting that surgical efforts should prioritize achieving stable union rather than pursuing exact anatomical length restoration. These results may help simplify surgical decision-making and potentially reduce operative complexity in the management of clavicular nonunion.

Footnotes

Author contributions

All the authors contributed to the conception and design of the study. Material preparation, data collection, and analysis were performed by DH Kim, HS Park, and YJ Cho, JH Nam, respectively. The first draft of the manuscript was written by HS Park. CH Lee and GC Lee participated in the design of the study and statistical analysis, and all authors commented on the previous versions of the manuscript. All authors have read and approved the final manuscript.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Ethical statement

ORCID iDs

Yong Jin Cho

Jong Hyeon Nam

GwangChul Lee

Data Availability Statement

The data that support the findings of this study are not openly available due to reasons of sensitivity and are available from the corresponding author upon reasonable request. Data are located in controlled access data storage at Chosun University Hospital.*

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Impact of clavicular length change on clinical outcomes after surgical treatment of nonunion: A retrospective study

Abstract

Purpose

Methods

Results

Conclusion

Keywords

Background

Methods

Patient selection and criteria

Surgical treatment method

Data collection and analysis

Statistical analysis

Results

Patient demographics and follow-up

Measurement reliability

Clavicular length analysis

Functional outcomes

Correlation analysis

Subgroup analysis

Complications

Discussion

Clinical implications

Study limitations

Conclusions

Footnotes

Author contributions

Declaration of conflicting interests

Funding

Ethical statement

ORCID iDs

Data Availability Statement

References