Jie Fang,Hui Zhu,Rongjian Shi,Dawei Zheng,Weiya Qi

Department of Hand Surgery,Clinical Anatomy Laboratory,Xuzhou Renci Hospital,Xuzhou 221004,Jiangsu,China

Keywords:Scaphoid fracture Hook of hamate fracture Carpal fracture Minimally invasive treatment

ABSTRACT Concomitant fractures of the hook of hamate and scaphoid are rare injuries to the wrist.Whenever these fractures cannot be effectively managed,nonunion or osteonecrosis is encountered.Subsequent treatment is thus much more challenging for a hand surgeon or orthopedist.Minimally invasive percutaneous internal fixation is an optimal treatment with the potential to minimize injury and reduce fractures.However,the control of iatrogenic injuries,including possible damage to the adjacent vital tissue,is a challenge that needs to be addressed.Herein,we describe the case of a 26-year-old man who presented with fractures to the scaphoid and hook of hamate in his left wrist.Minimally invasive treatment-with closed reduction and percutaneous fixation of the scaphoid,wrist arthroscopy,and closed reduction and percutaneous fixation of the hook of hamate-was performed at our institution.The Mayo score of the wrist,visual analog scale(VAS)for pain,grip strength,pinch strength,and wrist motion in radial/ulnar and flexion/extension deviation were recorded.Primary healing was achieved in both fractures.At the final follow-up,the Mayo score of the wrist was 100(excellent),the VAS score was 0(no pain),and the grip and pinch strength of his injured hand were 90.9% and 83.3%,respectively,compared with the contralateral hand (grip strength:left,50 kg;right,55 kg.Pinch strength:left,20 kg;right,24 kg).The radialulnar,flexion-extension,and forearm pronation-supination directions were 30°,140°,and 90°,respectively.Minimally invasive closed reduction with percutaneous internal fixation is an optimal technique with satisfactory outcomes for simultaneous fractures of the hook of hamate and scaphoid.Provided in this paper are details of the technique and technical suggestions for performing the procedure.

1.Introduction

The scaphoid is the most commonly fractured carpal bone;the incidence accounts for 90%of carpal bone fractures and approximately 2%-7%of all fractures.1,2This type of fracture is a public health issue,usually presents in young people with a mean age of 25 years,3who are the most active and productive working individuals.Epidemiological investigations indicate approximately 30 scaphoid fractures per 100 000 people per year in Europe.4

Hamate fracture does not occur as commonly as fractures of the scaphoid;these fractures account for approximately 2%of all carpal bone fractures and are more commonly associated with sports-related injuries.5They rarely occur in the general population.5Hamate fracture is of two main types,the hook and body fractures,with the hook fracture occurring more commonly than the body fracture.6

Scaphoid fractures associated with hamate fractures have rarely been reported in the general population;however,there are several case reports available in the literature.7-9The treatment indication of concomitant scaphoid and hamate fractures is limited at present.Herein,we present our treatment for simultaneous fractures of the hook of hamate and scaphoid with minimally invasive percutaneous internal fixation.

2.Case presentation

A 26-year-old man who fell on his left wrist sustained concomitant scaphoid and hook of hamate fractures.He visited our institution 19 hours after the injury(Figs.1 and 2).

Fig.1.The preoperative appearance of the injured hand and X-ray.

Fig.2.Preoperative CT of the patient.

The patient was placed in a supine position under brachial plexus anesthesia,with an electric pneumatic tourniquet on the injured upper arm.The wrist was suspended in a traction tower,and the fingers were suspended in Chinese finger traps.The countertraction on the arm was 4.5 kg.The 3-4 and 4-5 arthroscopic portals were used to evaluate the scaphoid fracture,assess chondral injuries and ligamentous fractures,and reduce the fracture under direct visualization of the joint surface(Fig.3).Once the fracture was optimally reduced,a K-wire was advanced to guide percutaneous fixation through the volar approach,and the position was confirmed by fluoroscopy.While the result was optimal,a cannulated drill was used to drill a hole along the K-wire,and a headless cannulated screw was inserted into the scaphoid under arthroscopic guidance to ensure the quality of the fracture reduction.Finally,the length and position of the screws were confirmed using fluoroscopy(Fig.4).

Fig.3.The direct vision of the scaphoid fracture under wrist arthroscopy.

Subsequently,closed reduction of the hook of hamate fracture was performed under fluoroscopy,using an 8-gauge syringe needle.Once the fragment was optimally reduced,K-wire guidance was inserted into the hook of hamate fracture through the syringe needle.After this,a 0.3-cm incision was made at the anchor point of the K-wire on the dorsal side of the hand while the tip of the K-wire penetrated the subcutaneous tissue.Position and trajectory were inspected using fluoroscopy.Once the results were optimal,a hole along the K-wire was drilled using cannulation through the dorsal approach.A headless compression screw was inserted into the fragments along the trajectory of the K-wire(Fig.5).Finally,the position and length of the screw were evaluated using fluoroscopy.After this,the wound was primarily closed with an absorbable suture and dressed with a self-adhesive bandage.

Fig.4.Reduced and internal fixation of the scaphoid fracture (intraoperative).

Fig.5.Reduced and internal fixation of the hook of hamate fracture(interoperative).

The diameter and length of the headless compression screw for the scaphoid were 3.5 mm and 26 mm,respectively,while those for the hamate were 2.5 mm and 22 mm,respectively.

On the second postoperative day,the physical rehabilitation program for the injured hand included active and passive motions.The self-adhesive bandage was removed two weeks postoperatively.Subsequently,the physical rehabilitation program for the wrist (both active and passive)began.

The patient was regularly examined by our department.The scaphoid and hook of hamate unions were confirmed by radiography and computerized tomography(CT)(Figs.6-8).At the final follow-up(16 months),the Mayo score of the wrist was 100(excellent);with VAS scores of 0(no pain);grip and pinch strength of the injured hand were 90.9% and 83.3%,respectively,compared with the contralateral hand (grip strength:left,50 kg;right,55 kg.Pinch strength:left,20 kg;right,24 kg).The radialulnar,flexion-extension,and forearm pronation-supination directions were 30°,140°,and 90°,respectively (Fig.9).Five months postoperatively,the patient returned to his original occupation.

Fig.6.X-ray of the injured hand at the final follow-up (16 months).Reduced and internal fixation (interoperative).

Fig.7.At the final follow-up (16 months),CT scans show that the primary union of the hook of hamate has been achieved.

Fig.8.At the final follow-up (16 months),CT scans show that the primary union of the scaphoid has been achieved.

3.Discussion

The scaphoid is the keystone of the carpus,which plays a critical role in the function of the wrist and hand,as well as in the function of the entire upper extremity.With factors not limited to anatomical characteristics and poor vascular supply,scaphoid fracture healing fails in approximately 5%-10% of all patients.1,10It often progresses to wrist arthritis within five years,which then leads to scaphoid nonunion advanced collapse.1,11Additionally,incorrect fracture healing can potentially result in dysfunction or disability.

Traditional open surgery requires joint capsule and ligament dissection,often resulting in complications such as joint stiffness,as well as the possibility of sustained injury to the scaphoid and its residual blood supply.12,13Instead of conservative treatment with cast immobilization,Herbert and AO compression screws have been used to fix the scaphoid and hamate for six weeks,and early active functional rehabilitation exercise of the injured wrist has been recommended to facilitate functional recovery.7-9

Wrist arthroscopy is currently the gold standard treatment for a wrist injury.14It can thoroughly evaluate the wrist through magnification,reduce iatrogenic injury,and evaluate accompanying ligament injury in a minimally invasive manner.14,15The treatment of scaphoid fractures by carpal arthroscopy involves limited damage to the dorsal intercarpal ligament and can maximize the protection of the ligament and periosteum,scaphoid vessels,and carpal proprioception.16

While scaphoid fracture is the most common type of carpal bone fracture,fractures of the hook of hamate are rare.5Due to non-specific and subtle clinical symptoms on physical examination as well as standard radiographs,such as inadequacy of the anteroposterior and lateral projections of the wrist,the diagnosis of carpal fractures is sometimes delayed,especially for the hook of hamate fractures.17

Fig.9.The outcomes of the function of the injured hand at the final follow-up (16 months).

Multiple treatments have been reported in the literature,and satisfactory results can be obtained by surgical excision or open reduction and internal fixation (ORIF),whereas iatrogenic trauma is larger in closed reduction and internal fixation.18Surgical excision of the hook of hamate is recommended as the standard procedure for athletes,with the advantage of rapidly returning to activity,such as sport,within six weeks.19Nevertheless,the biomechanical function of the hook of hamate for the flexor tendons of the fourth and fifth fingers may decline,and the grip power of the hand may be decreased.20Additionally,there is a risk of damage to the adjacent vital structures,including the motor branch of the ulnar nerve,the ulnar digital nerve of the fifth digit,and the flexor tendons of the fourth and fifth digits.21The aim of surgery is to adequately reduce fragments in order for the integrity of carpal alignment and the height of the wrist to be retained.However,the relatively small bony fragments and narrow operating space for implant placement add to the difficulty and challenge of treating carpal bone fractures.To date,there is no consensus on the optimal treatment of such fractures.

The management of simultaneous wrist fractures of the hook of hamate and scaphoid is rarely reported.To effectively treat these fractures,an initial and accurate diagnosis is required.CT is recommended as a diagnostic method due to its sensitivity (100%) and specificity(94.4%).22The fractures in our patient were identified by CT.

Minimally invasive fixation has been demonstrated to have a higher union rate than conservative treatment,in addition to relatively few complications.With the assistance of wrist arthroscopy,fractures can be visually and accurately reduced,followed by fixation with a headless cannulation compression screw.As a representative of minimally invasive surgery,it has potential advantages,including allowing assessment of the fracture,necessary debridement,and precise placement along the central axis of the scaphoid.A higher fracture union rate,shorter time to union,and a more rapid recovery are deemed to be the significant merits of percutaneous screw fixation.23Therefore,arthroscopically assisted percutaneous screw fixation was performed to treat the scaphoid,with the advantages of superior visualization and minimum invasiveness.Precise reduction was achieved for the patient,and the screw was accurately inserted along the central axis of the scaphoid.The patient underwent a closed reduction and internal fixation of the hook of hamate fracture.As a result,both minimal invasion and precise reduction were achieved without complications.Healing of the scaphoid and hook of hamate fractures was confirmed by CT,and primary healing was achieved without any complication after three months of follow-up.

Compared with surgical excision of the hook of hamate and ORIF,our procedure for bony union has the advantage of being potentially less invasive and without significant complications.Additionally,wrist and hand functions were satisfactorily recovered.

Following our procedure to treat simultaneous fractures of the hook of hamate and scaphoid,the patient had a favorable functional outcome.Minimal invasion and precise reduction and fixation are considered important contributing factors for favorable outcomes.A less invasive procedure combined with a stable fixation provides a precondition for early rehabilitation,including active and passive motion.Further research,including studies with more patients or a randomized controlled trial,is essential to investigate the statistical differences between surgical excision of the hook of hamate,ORIF,and conservative treatment.

4.Conclusion

Minimally invasive closed reduction with percutaneous internal fixation is an optimal treatment for simultaneous fractures of the hook of hamate and scaphoid to achieve satisfactory functional recovery.

Ethics approval and consent to participate

The need for ethical approval and consent to participate was waived as this is a case report.

Consent for publication

All patients provided written informed consent to publish the data contained within this study.

Competing interests

The authors declare they have no competing interests.

Authors’ contributions

Fang J:Operation,Data curation,Writing-Original draft.Zhu H and Qi W:Conceptualization,Methodology,Operation.Shi R:Visualization,Investigation.Zheng D:Writing-Review and Editing.