Although many methods have been described for closed reduction of displaced clavicular shaft fractures, none has been consistently reliable in achieving and maintaining reduction^1,2. Thus, displaced midshaft fractures of the clavicle typically heal in approximately the same position as that seen on initial radiographs, with a characteristic inferior, medially translated and anteriorly rotated deformity of the lateral fragment. Although it has been suggested that little functional loss results, more recent studies employing patient-oriented outcome measures (such as the patient-oriented, limb-specific Disabilities of the Arm, Shoulder and Hand [DASH] score) have suggested that some residual impairment is common^2-5. A mean score of 32 points on the DASH (on which 0 points indicates a “perfect” extremity and 100 points, complete disability) was reported in a study of 105 polytrauma patients with a clavicular fracture⁶. Hill et al. used a patient-oriented outcome questionnaire and reported a 31% rate of unsatisfactory outcomes in fifty-two adult patients following nonoperative treatment of a displaced midshaft clavicular fracture⁷.

A number of recent articles have characterized the symptoms reported with clavicular malunion^7-15, which is associated with substantial degrees of skeletal deformity, especially shortening of ≥2 cm. Subjective weakness was a consistent symptom in these series, but objective muscle-strength testing was limited. Oroko et al. used a spring balance with the arm in 90° of abduction and recorded strength to a maximum of 25 lb (11.3 kg)¹⁶. Nordqvist et al. used the “Nicholas manual muscle tester” in a similar setting¹⁷. Neither method appears to have the objective reproducibility or degree of sensitivity required to demonstrate subtle changes in strength, especially endurance strength.

The purpose of our study was to evaluate a series of patients with patient-oriented health measures and objective muscle-strength testing following healing of a displaced midshaft fracture of the clavicle that had been treated nonoperatively.

Materials and Methods

Areview of emergency room and fracture clinic records identified 107 patients in whom a displaced midshaft fracture of the clavicle had been treated nonoperatively at our institution between 1994 and 2000. All patients had been treated with a sling, and all showed clinical and radiographic evidence of healing. Following union, all patients had been offered formal physiotherapy, but compliance was variable. Patients were included in the study if they had a closed fracture with an intact neurovascular status, a normal contralateral upper extremity, no additional pathological condition (acute or chronic) affecting function of either upper extremity, clinical and radiographic evidence of fracture union, and an ability to complete the involved questionnaires and to comply with the muscle-strength testing. The exclusion criteria included an open injury (five patients), associated injuries or nerve lesions (thirty-two patients), and an inability or unwillingness to participate (seven patients). Thirty-three patients could not be located.

Thirty patients were included in this study. There were twenty-two men and eight women, with a mean age of thirty-seven years (range, nineteen to sixty-seven years). Sixteen dominant limbs and fourteen nondominant limbs were involved. All study participants returned for clinical assessment and objective muscle-strength testing. The mean follow-up time was fifty-five months (range, twelve to seventy-two months). Four patients were tested between twelve and twenty-four months following the fracture.

Outcome assessments were performed with the DASH and Constant shoulder score^5,18,19. The DASH is a responsive, validated, and reliable patient-oriented outcome measure for assessing disability of the upper extremity. A higher score means greater disability, with 100 points indicating a completely disabled extremity and 0 points indicating a “perfect” extremity. In the Constant shoulder score, the subjective parameters of pain and activities of daily living account for 35% of the total score and the objective parameters of range of motion and power account for 65% of the total score. A higher score (maximum, 100 points) is associated with better function and greater satisfaction, whereas a score closer to 0 is associated with greater disability.

Patients were asked if they were satisfied, partly satisfied, or dissatisfied with the outcome and why. They were also asked about their work status before and after the fracture.

The ranges of shoulder flexion, abduction, and external rotation were measured with a handheld goniometer with 18-in (45.7-cm) lever arms. The physical examination also included clinical measurement of clavicular length (from the sternoclavicular joint to the acromioclavicular joint) with a tape measure, and clavicular shortening was defined as the difference between the affected and unaffected sides¹⁷. Isometric muscle testing was performed with the Baltimore Therapeutic Equipment (BTE) Work Simulator (model WS-20; Hanover, Maryland) with use of a previously published protocol²⁰. The unaffected upper extremity was used as a control for each patient and was tested first. Patients were allowed to practice on the machine and then rest before testing. Isometric strength of shoulder flexion and abduction was measured with the arm at 90° and no flexion of the elbow. External rotation was measured with the arm abducted 45° and the elbow flexed 90°. Each reported strength measurement was the mean of three trials with a coefficient of variation of <15%. Values were expressed in inch-pounds and as a percentage of the contralateral (normal) arm. Endurance of shoulder flexion and abduction were tested with the elbow in extension and the arm beginning in a neutral position beside the body and moving through a full range of motion. Endurance of external rotation was tested with the elbow flexed 90° and the arm beginning in internal rotation and moving into complete external rotation. The endurance tests were terminated when the subject could not move the shoulder through a full range of motion. All testing was performed by independent examiners who had not been involved in the clinical care of the patients.

Initial and follow-up anteroposterior and 20° cephalad radiographs were made for each patient. Displacement and shortening were measured on the final follow-up radiographs.

This study was reviewed and approved by the St. Michael's Hospital Research Ethics Board (REB# 2K-065C).

Statistical Analysis

Statistical analysis was performed with the SAS system software package (SAS Institute, Cary, North Carolina). A paired t test was used to determine differences in motion between sides, and a Student t test was used to assess differences between groups. Comparison of rates between groups was performed with use of a Fisher exact test (two-tailed). A p value of ≤0.05 was considered significant. Pearson correlation coefficients were calculated.

Results

Patient Satisfaction

Fifteen patients were completely satisfied with the shoulder, seven were only partly satisfied, and eight were dissatisfied. Reasons for dissatisfaction included a sense of weakness, pain, displacement, or a bump. Six of the fifteen patients who were not completely satisfied were dissatisfied with the cosmetic appearance because of a bump or shortening of the clavicle even though they were able to perform all of their normal activities.

Return to Work

Eighteen patients had returned to their preinjury levels of work and recreational activity. Eight patients had returned to a less strenuous occupation. Four patients did not work or had not returned to work, in large part as a result of associated injuries (back injury, lower-extremity fracture, and visceral injury) or their sequelae.

Range of Motion

Motion was well maintained. The range of motion (mean and standard error) for the injured shoulder was 170° ± 20° of flexion, 165° ± 25° of abduction, and 79° ± 12° of external rotation. None of the values were significantly different from those for the normal, contralateral shoulder.

Outcome Scores

The mean DASH score was 24.6 points, compared with a published normative value for the general population of 10.1 points¹⁸, and the mean Constant shoulder score was 71 points, compared with a published normative value for the general population of 92 points¹⁹ (Fig. 1). Our subjects' scores were significantly inferior to the values for the normal population (p = 0.01 for the Constant score and p = 0.02 for the DASH score).

Muscle Strength

There was a decrease in the muscle strength of the injured shoulder. Compared with the strength of the uninjured arm, the maximum flexion strength and endurance in flexion were 81% and 75%, respectively, on the side of the injury; the maximum abduction strength and endurance in abduction were 82% and 67%; the maximum external rotation strength and endurance in external rotation were 81% and 82%; and the maximum internal rotation strength and endurance in internal rotation were 85% and 78% (Fig. 2). All strength values for the injured arm were significantly lower than those for the normal, contralateral arm (p < 0.05 for all).

Correlations

There was a strong inverse correlation between the DASH and Constant scores (r = -0.904, p = 0.01), indicating that a patient's report of less disability on the DASH corresponds to a higher objective Constant score. An inverse correlation between abduction endurance and shortening (i.e., an association between increased shortening and less abduction endurance) approached significance (r = -0.320, p = 0.06; Fig. 3). There was a correlation between a higher Constant score and stronger abduction endurance (r = 0.725, p = 0.001; Fig. 4). With the numbers available, there was no correlation between shortening and the DASH score (r = 0.315, p = 0.11) or the Constant score (r = -0.196, p = 0.44). However, there was a trend for patients with ≥2 cm of shortening to be more likely to have a DASH score of >30 points compared with those with <2 cm of shortening (a DASH score of >30 points was recorded for seven of eleven patients with ≥2 cm of shortening compared with three of nineteen with <2 cm of shortening, p = 0.06).

Discussion

Displaced midshaft fractures of the clavicle have traditionally been treated nonoperatively, with the expectation that little functional loss will result despite substantial residual radiographic malalignment^1-4. However, many previous studies depended on surgeon or radiograph-based outcome measures that may not have detected subtle deficits. There is increasing evidence that patients can have substantial dissatisfaction following a clavicular malunion because of symptoms including weakness and easy fatigability, especially with overhead work^7-15. Theoretically, these symptoms stem from residual strength deficits that could be identified by patient-oriented questionnaires (such as the DASH) and quantified with objective muscle-strength testing. In a previous report on fifteen patients with symptoms following clavicular malunion, twelve were bothered by shoulder weakness⁸.

Although there is some variability in the features of clavicular malunion, shortening in the medial-lateral dimension with inferior displacement and anterior rotation of the lateral fragment is seen in most cases^6-10. It is reasonable to conclude that shortening in the coronal plane has a negative effect on muscle-tendon tension and muscular balance. On a mechanical level, one could postulate that the strength most likely to be affected by clavicular shortening is that of the muscles whose action is primarily in the plane of shortening (coronal)—i.e., abduction. This was the case in our study, in which abduction endurance was the most negatively affected muscle strength (67% of the strength on the normal, contralateral side, on average). This finding may explain the trend toward a higher prevalence of patient dissatisfaction with increasing clavicular shortening (a DASH score of >30 points was recorded for seven of eleven patients with shortening of ≥2 cm compared with only three of nineteen with clavicular shortening of <2 cm). Correspondingly, there was an inverse relationship between shortening and abduction endurance in our study: increased shortening was associated with decreased abduction endurance strength. Interestingly, despite these findings, we did not find a statistical correlation between shortening and outcome, perhaps because, rather than there being a linear relationship between deformity and outcome, there is an “all or none” phenomenon, or a nonlinear relationship. Thus, abduction function may be well-preserved until a critical threshold of deformity, such as ≥2 cm of shortening, is reached, which then dramatically increases the percentage of poor outcomes.

Shortening has been implicated in symptomatic clavicular malunion in other reports. Hill et al.⁷ stated that midshaft clavicular fractures with >2 cm of shortening were more likely to result in a poor outcome than were fractures associated with less deformity. Chan et al.¹⁰ reported a length discrepancy of between 2 and 3 cm in four patients treated with clavicular osteotomy because of malunion, and we reported a mean shortening of 2.9 cm in our recent review of the cases of fifteen similar patients⁸. However, it is clear that other factors play a role in outcome since not all radiographic malunions are symptomatic. Rotation and/or anterior translation of the distal fragment is common but difficult to measure accurately; it may be that a combination of displacements is required to alter shoulder biomechanics or local anatomic relationships (i.e., the thoracic outlet) to a degree that results in symptoms.

The authors of other retrospective studies have not found that shortening correlates with outcome^16,17. However, these earlier studies had several limitations. The method of testing was relatively rudimentary, with no objective assessment of muscle strength and endurance, and relatively few patients with severe deformity or shortening were included. Also, radiographic and surgeon-based, rather than patient-based, outcome measures were used in these studies. Even though Oroko et al.¹⁶ could not demonstrate any relationship between clavicular shortening and shoulder function, they noted that the three lowest Constant scores (<60 points) were for patients with severe shortening.

The strengths of our study include the duration of follow-up (a mean of more than four years since the injury), use of patient-oriented outcome measures, and objective muscle-strength testing (especially of endurance strength). There were also several weaknesses. The sample size was relatively small, and a larger study may have provided a more complete picture of prognostic factors. A larger sample may also have revealed true differences or correlations that our study did not identify because of its small sample size (a beta error).

We are reluctant to make recommendations regarding the primary treatment of displaced clavicular fractures since our study showed only that there are strength deficits following nonoperative treatment and that is not proof that initial operative treatment would have been superior. Patients who were willing to return for testing may have been those who were unhappy with their outcome, and thus there may have been a selection bias toward those who were more likely to have residual weakness. Despite these drawbacks, we believe that our study is the first to document residual strength deficits following the nonoperative care of displaced clavicular fractures.

In conclusion, we detected residual deficits in shoulder strength, especially endurance strength, in this patient population. Clavicular shortening was associated with a trend toward decreased abduction strength, and shortening of ≥2 cm was associated with a trend toward greater patient dissatisfaction. This may account for the significant level of residual disability detected by the patient-based outcome measures following nonoperative care of displaced midshaft fractures of the clavicle. We believe that this study demonstrated major room for improvement in the outcome for individuals with this injury, and we are conducting a randomized clinical trial to test the hypothesis that primary operative care may be superior^21,22. ▪