Comparison of Minimally Invasive Operative Treatment with Conservative Treatment for Acute, Minimally Displaced Scaphoid Fractures at 12 Months' Follow-up

Abstract

Background  Minimally displaced scaphoid fractures can be challenging to diagnose and treat. Cannulated scaphoid screws have made percutaneous stabilization highly effective.

Questions  Would minimally invasive operative treatment of minimally displaced scaphoid fractures yield faster return to work when compared with patients treated conservatively? How do functional and patient satisfaction scores compare between the two groups at 12-months follow-up?

Patients and Methods  Records from 18 patients (mean age 28.6 years) treated surgically were retrospectively reviewed and compared with a group of 10 patients (mean age 33.3 years, p  = 0.74) treated nonoperatively. Inclusion criteria were a minimum follow-up period of 12 months and radiographic union. Time to return to work was compared between groups. At 12 months' follow-up, wrist range of motion (ROM) and grip strength were compared, as well as pain, satisfaction, and overall wrist function were evaluated by the visual analogue scale (VAS) and the Mayo modified wrist score (MMWS).

Results  The mean time to return to work for the operated group was 39.75 days, while for the nonoperated group it was 88.14 days ( p  = 0.002). At the 12 months' follow-up, mean ROM, grip strength, and VAS score did not differ between groups. The mean MMWS was 98.75 for the operated group and 87.5 for the nonoperated group, indicating a better result in patients treated operatively ( p  = 0.03). In addition, two failures of instrumentation were recorded, a seldom seen complication.

Conclusion  Percutaneous fixation of minimally displaced scaphoid fractures allows faster return to work and leaves patients more satisfied with their wrist function compared with plaster immobilization at 12 months' follow-up.

Level of evidence  This is a Level III, retrospective, case–control study.

Scaphoid fractures are more common in young, male patients in their third decade of life, following a fall, and they approximate 10% of all hand fractures and 60% of all carpal fractures. ^{1 2 3} Despite their frequency, these fractures can be challenging to diagnose and treat effectively. Early diagnosis and vigilant care are necessary to lead to a functional result and prevent altered wrist kinematics. The scaphoid is oriented in the carpus with an intrascaphoid angle averaging 40 ± 3 degrees in the coronal plane and 32 ± 5 degrees in the sagittal plane, and is the only carpal bone that bridges the proximal and distal carpal rows and acts as a tie-rod. The strong connection of the scaphoid to the lunate by the scapholunate interosseous ligament limits scapholunate motion and stabilizes the proximal row. Thus, scaphoid malunion or nonunion will lead to chronic pain and dysfunction of the wrist and arthritis, affecting the entire upper extremity. ⁴

Internal fixation of scaphoid fractures has been greatly facilitated by the use of specially designed headless bone screws, while the advent of cannulated scaphoid screws has made closed (percutaneous) stabilization of the scaphoid a reality. Percutaneous fixation of scaphoid fractures is usually reserved for nondisplaced fractures and has been shown to be highly effective. ^{5 6 7 8 9} Potential advantages of the percutaneous approach include faster time to union and return of function, preservation of the extrinsic carpal ligaments, less risk of violating the already tenuous blood supply to the scaphoid, and a shorter time to union. ^{6 10 11}

Would minimally invasive operative treatment of minimally displaced scaphoid fractures yield faster return to work when compared with patients treated conservatively? How do functional and patient satisfaction scores compare between the two groups at 12-months follow-up? We hypothesized that in cases of undisplaced or minimally displaced scaphoid fractures, minimally invasive operative treatment would yield improved outcomes in terms of time to return to work, and functional and subjective wrist scores and we compared a group of patients treated conservatively with patients treated operatively via percutaneous fixation.

Material and Methods

Study Design

This is a retrospectively designed case–control study. Although this study was a retrospective review of patient records, the study obtained approval from the institutional ethics committee. Two groups of patients were compared, one conservative and one surgical for the period 2008 to 2018.

For the surgical group, all following inclusion criteria needed to be met: (1) minimally invasive (percutaneous) surgical treatment of acute, undisplaced, or minimally displaced (<1 mm) scaphoid fractures, (2) attendance of all scheduled follow-up consultations, (3) minimum follow-up period of 12 months, and (4) radiographic union. Exclusion criteria: (1) patients with incomplete records, (2) age under 17, and/or (3) open surgical treatment.

For the conservative group, all following inclusion criteria had to be met: (1) conservative treatment of acute (<4 weeks), undisplaced, or minimally displaced (<1 mm) scaphoid fractures with plaster cast, (2) attendance of all scheduled follow-up consultations, (3) minimum follow-up period of 12 months, and (4) radiographic union. Exclusion criteria: (1) patients with incomplete records, (2) age under 17.

For both groups, the data compared from the 12 months' follow-up consultation were: (1) range of motion (ROM), (2) grip strength, (3) patients' pain, satisfaction and overall wrist function as evaluated with the visual analogue scale (VAS) and the Mayo modified wrist score (MMWS). We also compared time to return to work between groups, as documented in previous follow-up consultations.

Surgical Group

Initial research showed that 144 patients with acute, undisplaced, or minimally displaced scaphoid fractures were operatively treated in our department between 2008 and 2018. Eighteen of them fulfilled the criteria to be included in the surgical group of this study. Their mean age was 28.6 years (standard deviation [SD] 10.1, range 17–49), all male, with injury of the dominant hand in nine cases (7 right –11 left side injury; Table 1 ). No patient suffered from diabetes or other major comorbidities. Thirteen out of 18 patients in the surgical group were smokers. The majority of patients that underwent surgical treatment (16/18) had a waist fracture, while two had a proximal pole fracture. They were operated within 1 week from injury. All patients were treated with the use of a headless cannulated compression screw from four different manufacturers (7 Twinfix [Stryker Inc], 3 Acutrak [Acumed Inc], 5 Kompressor [Kinetikos Medical Inc], 3 Herbert [Zimmer Inc]), through a palmar (16) or dorsal (2) percutaneous approach. The patients were discharged with written instructions to follow a short regime of simple exercises at home, without supervision by a physical therapist. A short-arm cast was applied for 2 weeks after surgery and no further rehabilitation was deemed necessary. All patients were evaluated clinically and radiographically at 5, 7, and 12 weeks and at 6 and 12 months. Patients were followed for a mean period of 53.3 months (SD 26.1) and potential complications were recorded.

Table 1. Presentation of sample demographics and results.

	Surgical group	Conservative group	Significance
Mean age (SD) in years	28.6 (10.1)	33.3 (10.6)	p  = 0.2
Sex	18 males	7 males–3 females	n/a
Side of injury	7 right–11 left	5 right–5 left	n/a
Mean time for union (SD) in weeks	6.17 (0.69)	10.5 (1.02)	p  < 0.001
Mean time to return to work (SD) in days	39.75 (10.36)	88.14 (19.6)	p  = 0.01
Mean ROM (SD)	118.8 (3.1)	116.3 (4.3)	p  = 0.28
Mean MMWS (SD)	98.75 (4.14)	87.5 (8.5)	p  = 0.03
Mean VAS	1.7	1.6	p  = 0.3

Abbreviations: MMWS, Mayo modified wrist score; ROM, range of motion; SD, standard deviation; VAS, visual analogue scale.

Conservative Group

Initial research showed that 102 patients with acute, undisplaced, or minimally displaced scaphoid fractures were treated conservatively in our department between 2008 and 2018. Ten of them fulfilled the criteria to be included in this study. These patients suffered from a waist fracture, they were male in their majority (7/10), with mean age of 33.3 years (SD 10.6, range 18–48), and with injury of the dominant hand in seven cases (5 right – 5 left side injury; Table 1 ). No patient suffered from diabetes or other major comorbidities. Smoking habits unfortunately were not routinely recorded at the outpatient department for patients treated conservatively. Four of them were treated with long-arm cast and six with a short-arm-thumb cast, for a period of 6 to 10 weeks, until radiographic and clinical union. After removal of the cast the patients underwent a physical therapy protocol of 1-month duration. All patients were evaluated clinically and radiographically at 6, 9, and 12 weeks and at 6 and 12 months. The mean follow-up time was 31.8 months (SD 17.5, range 12–49) and potential complications were recorded.

Statistics

Descriptive statistics and Student's t -test for independent samples were appropriately used.

Results

Age between groups did not differ statistically, nor did hand dominance. The mean time for radiographic union was 6.17 weeks (range 5–7, SD 0.69) for the MIS group and 10.5 weeks (range 9–12, SD 1.02) for the cast group. These values were significantly different ( p  < 0.001). The mean time to return to work for the operated group was 39.75 days (range 20–55 days, SD 10.36), while for the nonoperated group it was 88.14 days (range 67–130 days, SD 19.6). The difference in time to return to work between groups was statistically significant ( p  = 0.002).

At the 12 months' follow-up, mean ROM for operated group was 118.8 degrees (SD 3.1), and for nonoperated group was 116.3 degrees (SD 4.3). Their difference did not reach statistical significance. Grip strength did not differ between sides and groups. The mean MMWS for the operated group was 98.75 (SD 4.14) while the mean MMWS for patients treated nonoperatively was 87.5 (SD 8.5). MMWS was significantly higher—indicating a better result—in patients treated operatively ( p  = 0.03). The mean VAS score was 1.7 for the operated group and 1.6 for the nonoperated group and the difference was not significant ( p  = 0.3; Table 1 ).

The complication report is quite limited but unusual. There were two almost identical failures of instrumentation (tip of screwdriver breakage intraoperatively during screw tightening, one of which was protruding and was removed immediately) ( Figs. 1–5 ). No complications such as infection, hematoma, complex regional pain syndrome, malunion, or nonunion were observed in any of the groups ( Figs. 6–8 ).

Fig. 1.

Preoperative radiograph of a 26-year-old male patient, left nondominant hand, after motor vehicle accident, resulting in a waist fracture of the scaphoid and subtrochanteric ipsilateral femoral fracture.

Fig. 2.

Immediate postoperative radiograph of the patient from Fig. 1 , depicting the cannulated screw and the broken tip of screwdriver protruding from scaphoid.

Fig. 3.

Immediate postoperative radiograph of the patient from Fig. 2 after removal of the broken tip of screwdriver.

Fig. 4.

( A, B ) One-year postoperative radiographs (anteroposterior and lateral) of the patient from Figs. 1 and 2 , depicting union of the operated scaphoid fracture.

Fig. 5.

Immediate postoperative radiograph of a 22-year-old male patient with left scaphoid fracture, depicting the cannulated screw and a fragment of the broken tip of screwdriver, which however, was not protruding from the scaphoid.

Fig. 6.

( A, B ) Preoperative radiographs (anteroposterior and lateral) of a 20-year-old male patient with a waist fracture of the scaphoid of his right dominant hand.

Fig. 7.

( A–C ) Immediate postoperative radiographs of the patient from Fig. 6 depicting screw placement in different planes.

Fig. 8.

One-year postoperative radiograph of the patient from Fig. 6 depicting union of the operated scaphoid fracture.

Discussion

Cast immobilization for minimally displaced scaphoid fractures had been the treatment of choice for previous decades. However, this treatment pathway is not without drawbacks. The main disadvantages of cast treatment are longer immobilization time, joint stiffness, and longer time to return to manual work. Immobilization may be needed for up to 3 months, and patient compliance is thus often unsatisfactory, especially in the presence of minor symptoms, when plaster casts may be discarded early, resulting in delayed union or nonunion. ¹² Cast immobilization may also lead to ongoing pain and reduced ROM and grip strength. Percutaneous fixation, on the other hand, is aimed at reducing the damage to blood supply and soft tissue, allowing early mobilization of the wrist and early return to manual work. It can be performed through either the volar or dorsal approach—the former being more popular because of better clinical outcomes, easier access, and fewer reported complications. ¹³

Several experimental studies assessed different implant fixations for the acute scaphoid fracture. These studies compared first with second generation screws with clear advantage of cannulated screws, as well as second generation screws of different manufacturers. The biomechanical parameters tested were stability, load bearing capacity, and rotational stability with the use of compression tests, pullout, and pushout tests in polyurethane foam or cadaveric bone. Results were variable, as the studies also included experimental implants or additional implant placement. ¹⁴ In addition, some of these studies only provided a vague idea of the efficacy of an in vivo osteosynthesis and thus, the use of specific screws still relies largely on availability, cost, and surgeon's preference. ^{15 16 17 18 19 20}

The most prominent difference in the study was time to return to work between the two groups, favoring the operated group. A recent meta-analysis of four studies comparing operative (both open and percutaneous fixation) and conservative treatment of stable scaphoid fractures, reached the same conclusion. ²⁰ In the operated group, the time to return to work ranged from 20 to 55 days. In a study presenting results following percutaneous treatment of 15 scaphoid fractures classified as B2 according to Herbert and Fisher classification, the time to return to work varied from 18 to 40 days, depending on patients' occupation. ²¹ Bond et al in a prospective randomized study in military personnel found that 11 young patients (mean age 24 years) treated with a percutaneous method of fixation returned to work after 8 weeks. The age-matched conservatively treated group, returned to work 7 weeks later. ²² In another randomized controlled trial, McQueen et al reported that 26 patients treated with percutaneous fixation of B1 (1/26) and B2 (25/26) fractures returned to work at a mean of 3.8 weeks. Conservative group returned to full employment at a mean of 11.4 weeks. ¹¹ A recent meta-analysis of 376 patients, examining the outcomes of nonsurgical management versus exclusively percutaneous fixation of minimally and nondisplaced scaphoid fractures showed, similarly to our results, that the mean time to return to work was 76 days in the conservative treatment group versus 46 days in the operative treatment group ( p  < 0.05). Both groups included manual workers and athletes. ²³ Return to full employment naturally depends on the job description and requirements and patient's motivation, however, operative percutaneous fixation of stable waist fractures appears to offer an advantage over conservative approach.

We report functional scores at 1-year follow-up for both groups. Mean flexion-extension ROM and grip strength did not reach statistical significance between groups. MMWS, which reflects comparison with the unaffected side and involves pain perception, was significantly higher in patients treated operatively in this study. Most authors of randomized trials and meta-analyses observed that ROM and grip strength do not differ between operative and conservative groups, at 12 months or later follow-up consultations. ^{11 24 25 26 27} A difference can be statistically evident at 2, 3, or 6 months follow-up favoring surgery, but not at 1 year following treatment. Outcomes remained similar even after more than 12 months of follow-up. One possible explanation of improved early results after operative treatment, is that screw fixation is more reliable and therefore achieves adequate stability and allows early wrist mobilization, leading to improved strength. It should be noted that measurement of these outcomes is vulnerable to observer bias and results should be assessed with caution. In addition, grip strength and ROM outcomes do not provide a measure of patient satisfaction with treatment. ²⁵

Concerning the complications documented in the literature, no significant difference has been observed between operative and nonoperative treatment in a meta-analysis of six randomized controlled studies. ²⁴ The complications assessed were nonunion, further surgery, malunion, and osteoarthritis. The independent risk of delayed union, probably the most devastating complication in this setting, was found to be significantly lower with operative treatment, with a 74.6% reduction in relative risk when compared with nonoperative treatment. However, a number-needed-to-treat analysis revealed that 23 patients would have to undergo operative treatment to prevent a single delayed union. Routine screw fixation would therefore expose an unacceptably high number of patients to the risks of surgery, especially when another meta-analysis agrees that the risk of nonunion is not significantly different between operative and nonoperative treatments. ^{24 25} The present study expands the range of potential complications and raises concern on instrumentation failure (screwdriver tip breakage) and potential need for reoperation, a complication that—to the best of authors' knowledge—has not been reported previously.

The mean primary costs of medical consultations after a scaphoid fracture consist of serial radiographs, medical visits, plaster and plaster replacement costs and surgery where applicable. Consequent costs are leave of absence from work, compensation cost, and insurance claims. Primary costs were found to be significantly higher and mean secondary costs were significantly lower in patients that were operated on than in conservatively treated patients and overall, operative treatment was less expensive than conservative treatment in undisplaced scaphoid fractures, but the difference was not significant. ²⁸ Papaloizos et al reached the same conclusion. ²⁹ Vinnars et al compared the direct and indirect costs of internal fixation and cast treatment in acute scaphoid fractures and revealed that in nonmanual workers, total costs were lower after casting than after surgery. ³⁰

This study is not without limitations. A retrospective study has inherent methodology disadvantages, such as relying on adequate record keeping and population selection bias. Another limitation of this study is the relatively small number of cases in each treatment group. The results of this study add and expand on previously published research on minimal invasive surgical treatment of scaphoid fractures at 1-year follow-up.

Conclusion

Percutaneous fixation of minimally displaced scaphoid fractures allows faster return to work and leaves patients more satisfied with their wrist function compared with plaster immobilization at 12 months' follow-up consultation.