1 Introduction

The most frequently fractured carpal bone is the scaphoid, which accounts for 50–80 % of all carpal bone fractures in young patients.¹ In the general population, the yearly incidence of scaphoid fractures varies from twenty-nine to forty-three per lac.²

It is most common in young males aged fifteen to twenty-nine years, who also had the highest frequency of non-union rate and the longest duration to unite.³ Although most scaphoid fractures are diagnosed and treated effectively, non-union can be expected to occur in 5 %–10 % of cases even with adequate treatment.⁴

In the long-term follow-up, untreated scaphoid nonunion can lead to pain, carpal collapse, radiographic changes of osteoarthritis, and disability.^5,6

Several surgical procedures are used to treat scaphoid nonunion. However, the gold standard technique for scaphoid nonunion treatment is still unclear.⁷

Bone grafts and internal fixation are frequently used in the management of scaphoid nonunion. K-wires and compression screws are widely used internal fixation devices.⁸

Despite the fact that compression screws have an 80%–90 % probability of bony union, prior publications detailed several drawbacks.⁹ Studies say that compression screws may lead to cortico-cancellous graft damage or displacement. Also, compression screws used with cancellous grafts may result in the reduction of scaphoid length, which is unfavorable for pursuing wrist biomechanics.¹⁰

Our study aimed to assess both the clinical and radiological results of treating scaphoid waist nonunion with an iliac bone graft and fixation with double K-wire.

2 Material and methods

This study was conducted between January 2018 and July 2023, after taking approval from the institutional ethics committee. Iliac crest bone graft and paired K-wires were used in the surgical fixation of 22 patients with nonunion of scaphoid. Medical records of patients were reviewed, including information on their gender, age, symptoms, and duration of follow-up. The functional evaluation was carried out by using the modified Mayo wrist score system. We measured grip strength, pain, and range of motion (ROM). A goniometer was used to measure the range of motion, which was then compared to the other side. The maximum grip strength on the injured hand was measured, and the results were determined as a percentage of the full strength on the opposite hand. The visual analog scale (VAS) was used to assess the severity, progression, and intensity of pain. Radiological assessments were done on lateral views of the wrist with the forearm rotation in neutral and posteroanterior (PA) views with a 20° ulnar deviation. Radiograph measurements taken before and after surgery were compared and examined.

2.1

2.1 Inclusion criteria

The study population included the following characteristics: (1). Age range of 17–45 years; (2). Confirmed scaphoid waist fracture nonunion diagnosed by imaging, and greater than six months of injury (Fig. 1).

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Fig. 1 Pre-operative radiographs (right wrist) of a 29 year old male with scaphoid fracture nonunion.

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2.3

2.3 Surgical procedure

Under general anesthesia, the palmar approach was used for the operative procedure. A 2–3 cm incision was made in line with the flexor carpi radialis tendon (FCR) and then taken distally in line with the first ray towards the scaphoid tubercle and scaphotrapezial joint to access the scaphoid from the volar side. A longitudinal capsulotomy was performed to expose the scaphoid. Two K-wires were inserted into the proximal and distal fragments, acting as joysticks to distract the non-union site. The non-union site was debrided as well as curetted. The sclerotic bone and fibrous tissue were removed until normal vascularized bone was visible at the nonunion site (Fig. 2a). From the iliac crest, an appropriate-size cortico-cancellous bone graft was then harvested. The bone defect was filled with a cancellous bone graft, and a wedge-shaped cortico-cancellous bone graft was placed in the fracture gap to maintain the reduction and restore the scaphoid height (Fig. 2b, c). Two 1.5 mm-diameter K-wires were inserted convergently from the distal end of the scaphoid tubercle, passing through the bone graft to the proximal portion, at 45° dorsal and 45° ulnar to the neutral plane (double 45° direction) (Fig. 2d). The first K-wire was positioned as optimally as possible in the center, at the right angle to the fracture line, and best aligned with the scaphoid's long axis. After that, the second K-wire was placed. The capsule was closed with interrupted 3-0 Vicryl sutures. Using a fluoroscope, the reduction, alignment, and K-wire positions were verified (Fig. 2e). To reduce irritation to the skin and enhance wrist range of motion, both K-wires had been bent and cut adequately.

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Fig. 2 (a) Fibrous tissue and sclerotic bone were thoroughly debrided and curetted, (b), (c) Harvested wedge-shaped iliac crest bone graft (b), and inserted into the nonunion site (c); (d), (e): Fixation was done by double K-wires (d), and position of K-wires were confirmed by radiograph (e).

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3 Follow up

4 Results

This study included a total of 22 cases with scaphoid nonunion. Out of the twenty-two cases, twenty (90.9 %) were men and two (9.1 %) were a women. The study's participants have an average age of 27 ± 4.5 years. The maximum age of the patient in our study was 45 years, and the minimum age was 17 years. Of the 22 patients, 10 (45.5 %) were in the 25–30 age range, 6 (27.3 %) were in the 31–35 age range, 4 (18.2 %) were less than 25, and 2 (9.1 %) were beyond 36 years. The majority of non-union cases (72.7 %) were categorized as fibrous nonunion, while 27.3 % were classified as sclerotic. The average period between injury and surgery was 10.5 ± 2.5 months (range: 7.5–15 months). The average follow-up period was 15 ± 3 months (range: 12–18 months), (Table 1).

When compared to preoperative values, all outcome scores were significantly enhanced at the time of the last follow-up. Furthermore, compared to preoperative radiographs, there was a remarkable improvement in the radiological parameters. Bony union was accomplished in 20 (90.9 %) of the 22 patients. The average range of motion before surgery for extension was 60.5 ± 8.5° SD and for flexion, it was 70.5 ± 9.7° SD. The postoperative range of motion increased to 63.5 ± 9.5° SD for extension and 73.2 ± 10.5° SD for flexion. The average grip strength was 53 kg, compared to 56 kg in a normal hand. Despite this, the difference was statistically insignificant. The average VAS score was 5.0 (4–9) before surgery and 1.0 (0–2) at the last follow-up. The modified Mayo wrist score improved significantly (p-value less than 0.05), going from 65.5 ± 7.5 SD preoperatively to 86.7 ± 9.5 SD postoperatively. Six patients (54.5 %) had excellent results; four patients (36.4 %) had good results; and one patient (9.1 %) had fair results. The scapholunate angle improved significantly, which went from 67 ± 8.5° SD preoperatively to 53.2 ± 4.5° SD, and the radio scaphoid angle also improved significantly to 50.7 ± 4.5° SD, (Table 2).

There were no serious complications for any of the patients. Although two patients complained of minor pain and functional discomfort, he refused to have another procedure. The radiographs of one patient revealed K-wire migration. Despite this, the patient achieved bone union. There was no pain at the surgical site following K-wire removal. The radiological and functional outcomes at the last follow-up have been shown in (Fig. 3a and b).

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Fig. 3 (a) The post-operative radiographs of right wrist at 15 months of follow-up. (b) Functional outcomes at 15 months of follow-up showing range of motion and grip strength.

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5 Discussion

Scaphoid nonunion is a condition caused by a precarious vascular supply and a high incidence of delayed diagnosis. Delayed union is defined as failure to unite within three months, and nonunion is defined as failure to unite within six months. While vascularity may play a role in scaphoid nonunion, stress vectors over the scaphoid during motion might also hamper healing.¹¹

The primary objective of surgical treatment for scaphoid fracture nonunion is to restore wrist function. To improve functionality, bone union and scaphoid alignment must be carried out. Re-establishing scaphoid length has been shown to reduce discomfort, enhance grip strength, and avoid degenerative changes.¹²

Numerous fixation techniques can be employed for scaphoid nonunion, such as screws, staples, plates, and K-wire with bone grafting. The use of compression screw devices may result in further graft splitting or graft shifting, which could lead to malreduction, graft failure, and ultimately nonunion. Despite a biomechanical study demonstrating that compression screws provide greater stability in fixation than K-wires,¹³ various studies have demonstrated equivalent clinical outcomes between compression screws and K-wires.^14,15

According to a study including 151 patients, cortico-cancellous iliac crest bone graft and K-wire fixation have proven to be the most dependable and effective method for achieving bone healing in cases of existing scaphoid non-union, with a 97 % success rate.¹⁴

Studies showed that the union rates with K-wire and bone graft ranged from 55 % to 97 %,¹⁶ whereas 84 % of cases of scaphoid nonunion with compression screws and bone grafts resulted in union.¹⁷ As with previous studies on K-wire and screw, our results (90.9 %) are consistent.

According to Meisel et al., union rates for nonunion scaphoid fractures treated with iliac crest bone grafting and K-wire fixation were either higher or similar to those of other techniques.¹⁸

The scaphoid union rate may also be affected by the type of bone graft that is utilized. Bone grafts harvested from the iliac crest have demonstrated superiority over cortico-cancellous bone grafts derived from the distal radius. The cancellous iliac bone grafts have a higher potential for osteogenesis and encourage rapid incorporation and revascularization at the nonunion site due to their thicker trabecular architecture and larger concentration of osteoblasts and osteocytes.¹⁹

It is commonly recognized that compression of cancellous bone graft by compression screw speeds up the healing process of bones. On the other hand, the use of compression screws may result in a greater amount of bone grafts being compressed or displaced, which could cause loss of scaphoid length and height as well as interfere with appropriate carpal mechanics.¹⁰

As we know, K-wires cannot compress the nonunion site, thus it must be reduced before K-wire insertion.

The advantages of K-wires fixation for treating scaphoid nonunion include the fact that it is a cost-effective technique. K-wires occupied a smaller connecting surface area than compression screws. Because of this, more of the bone graft is in contact with fragment surfaces, providing a more stable bony union. It also allows for the restoration of the upper limits of carpal height and length while avoiding compression.¹⁰

Furthermore, improperly positioned K-wires should be easily adjusted with lesser bone loss. Additionally, in the nonunion site, two or three K-wires can improve rotational stability in comparison to a single compression screw.²⁰

In a study by Chen et al. reduced scaphoid fragments were fixed by using divergent K-wires in 26 patients with nonunion of the scaphoid. Their study showed a 100 % union rate within four months of surgery and good to excellent functional results in all individuals. The follow-up time varied from three to six years.²¹

The study conducted by Hegazy et al. stabilized scaphoid fracture nonunion by placing multiple convergent 1.1-mm K-wires retrogradely, leading to a 98 % union rate.²²

In their study, Holger et al., show that Kirschner wire internal fixation for scaphoid nonunion can be a reliable and safe procedure with good functional results and comparable bone union rates with other surgical techniques.²³

In comparison to other fixation techniques, K-wires are typically easy to insert. Additionally, the temporary nature of K-wire fixation allows for early and easy removal while minimizing long-term hardware problems.²⁴

K-wire fixation does, however, have certain possible disadvantages, including decreased resistance to fracture leading to fixation failure, infection of the pin tract, pin breakage because of metal fatigue, and a longer time of immobilization required due to a weaker fixation strength, which may lead to joint stiffness.²⁵

Despite this, the present study showed that for scaphoid nonunion, K-wire fixation combined with iliac bone grafts may produce favorable radiographic and clinical results.

6 Conclusion

Based on our observational study, we concluded that iliac bone graft with double K-wire fixation for the treatment of scaphoid nonunion is a dependable and efficient surgical procedure. This procedure produces favorable functional and radiological results. It is a reliable and safe substitute for the conventional headless compression screw fixation. However, a larger sample size and longer follow-up period should be required for the conclusion.

CRediT authorship contribution statement

Navin Kumar Yadav: Conceptualization, Methodology, Formal analysis, Investigation, preparation, Writing – original draft, Writing – review & editing, Visualization. Pavan Pradhan: Supervision, Conceptualization, Methodology.

Guardian/patient's consent

Written consent given by patient and patient's guardian.

Ethical statement

Approval from the Institutional Ethics Committee of Baba Raghav Das Medical College and Nehru Hospital (approval number: EC/NEW/INST/2020/1275).

Funding

Nil.