Diagnosis of a hamate hook fracture with 3D reconstruction of computed tomography images: A case report and review of literature

Abstract

We report the case of a 19-year old man who presented to our institution with a history of pain of one week in the ulnar side of the left wrist and continuous pressing sensation in the palm. According to patient, there was no history of acute hand trauma. The conventional roentgenograms did not show the fracture and computerized tomographic (CT) scanning demonstrated a complete fracture of the hook of the hamate. The patient was given a surgical intervention and the hamate bone was reduced through a palmar skin incision. After surgery, the operated hand was immobilized in a wrist brace and the patient was put on a rehabilitation protocol. At the last follow-up, the patient was able to return to normal living activities without any symptoms. We reviewed the latest articles of the past 18 years and compared the research studies related to the diagnosis and treatment of the hamate hook fracture. Our conclusion is that CT scan is the most effective diagnostic tool for detecting the hamate hook fracture. Three-dimensionally (3D) reconstructed images based of CT could provide more accurate and insight illustration for better evaluation in surgical planning.

Keywords

Hamate hook fracture open reduction and internal fixation computed tomography 3D reconstruction

1. Introduction

The hook of the hamate fracture constitutes nearly 2–4% of carpal fractures and is typically caused by a direct blow, such as grounding a golf club or checking a baseball bat [1, 2]. Because of the variable and occult presentation of the fracture, the diagnosis can be challenging [3]. Acute fractures of the hook of the hamate are frequently not seen on plain radiography. A carpal tunnel view of plain film tomograms of the wrist and axial CT scanning can be useful for accurately diagnosing and defining the pattern of the lesion [4, 5].

We present a rare case of the hook of the hamulus fracture in a left-hand (non-dominant hand) of a young student. To the best of our knowledge, this is the first case report of a hook of hamate fracture in a Chinese juvenile to date. In this study, a technology was developed to generate a video originated from 3D reconstruction of CT images. With the aid of the 3D video, the fracture was finally diagnosed and treated with open reduction and internal fixation (ORIF) through a Bruner incision. We searched the published literature of the last 18 years and performed a systematic review of the articles about hamate hook fracture. A brief comparison of the diagnosis and treatment of the hamate hook fracture was made with a short demonstration in this study.

2. Case report

A right-handed,19-year-old man presented to us with complaints of pain for one week in the ulnar side of the left wrist and in the hypothenar area; the pain was insidious in onset and gradually progressed in intensity with no definite history of any acute trauma to his hand. The symptoms were hypothenar pain worsening with activities requiring tight griping movement such as griping bottles. On clinical examination we found that he had deep point tenderness over the hook of the hamate region. There was no swelling in the region, but grip strength was reduced compared to the opposite side, with a positive hamate pull test [6]. There were no symptoms of ulnar nerve compression.

Plain radio-graphs revealed a swollen area in the hamate but were largely non-conclusive results (Fig. 1). The plain film x-ray showed no positive signs in the anterior-posterior view. CT scanning demonstrated a complete fracture of hamate hook fracture, and there was no evidence of a vascular necrosis of the ulnar nerve injury (Fig. 2). Further, we integrated all CT data into a 3D fracture model by Mimics software 18.0 (Materialise NV Technologielaan, Leuven, Belgium). The video clearly showed that the hamate hook fragment, which separated from hamate bone (Fig. 3).

Fig. 1

Conventional roentgenograms failed to show the hamate hook fracture with (A) anterior-posterior view and (B) a lateral view.

Fig. 2

Photographs of 3D CT scan showing the hamate hook fracture (the hamate body depicted by arrow and the hamate hook depicted by red frame) including images of (A) horizontal plane, (B) sagittal plane, (C) 3D CT scan image of the anterior-posterior view showing no positive fracture, and (D) 3D CT scan image of the lateral view showing the hamate hook fragment.

Fig. 3

Illustration of a dynamic video section based on 3D reconstruction of CT images.

We treated the patient with open reduction and internal fixation (ORIF) through a Bruner incision (Fig. 4A) [7]. During surgery, we found that the proximity of the hook of the hamate was near to the fifth profundus tendon and the motor branch of the ulnar nerve (Fig. 4B). The hamulus fracture was reduced and fixed with countersink head screws (Fig. 5A and 5B). After surgery, the operated hand was immobilized in a wrist brace and the patient was put on a rehabilitation protocol. The post-operative recovery of the patient was uneventful (Fig. 5C and 5D). After 10 months, the wrist examination showed a range of motion (ROM) of 70° of pronation, 80° of supination, 30° of extension and 70° of flexion. Contralateral wrist ROM was normal. The grip strength of the left hand was 10Kg and pinch was 4.5Kg while the right hand (dominant hand) was 30Kg and 10Kg, respectively. The left hand finger mobility was not limited and DASH score preoperatively was 35 and postoperatively 10. The status of the hand was much better after surgery.

Fig. 4

(A) shows that a Bruner incision is used directly over the hook of the hamate to gain adequate exposure: H, hamate. P, pisiform; while (B) shows that the ulnar neurovascular structures are gently retracted to expose the hook of the hamate.

Fig. 5

It shows a set of intra-operative AP and orthogonal fluoroscopy images recorded after the fracture was reduced and fixated with (A) anterior-posterior view and (B) lateral view, and post-operative radiograms within 10 months after surgery with (C) anterior-posterior view and (D) lateral view.

3. Review of the literature

Literature searches were limited to articles published between January 2000 and September 2018, printed in English, and sampling hamate hook fractures. Relevant articles were sourced from the PubMed, Embase, and Ovid databases from inception through September 20, 2018, while special hand surgery and sports journals, and reference lists of related articles were included if deemed to be of value. Our aim was to compare the diagnosis and treatment of the hamate hook fracture, so the case report was excluded from these search fields. The databases were searched using the following terms: (“hamate hook fracture”) OR (“hook of hamate fracture”) OR (“hamulus ossis hamati fracture”) NOT (“case report”).

Our literature search identified 346 potentially relevant studies, of which 55 were considered for inclusion after title and abstract review. 177 of these 291 studies were excluded after full text review. A total of nine retrospective studies were therefore included in this review [8 –16]. Details of the selected studies are shown in Table 1. These studies were conducted in China (1/9,11 %), Spain (1/9, 11%), Germany (1/9, 11%), UK (1/9, 11%), and USA (5/9, 55%). We were able to extract useful data on the results of the surgical intervention from seven studies.

Table 1
Characteristics of included retrospective analysis of studies published in the last 18 years

Study	Year	Location	Number of patients			Gender		Mean age (years)	Average follow up (months)	Trauma
Study	Year	Location	Conservative	Excision	ORIF	Male	Female	Mean age (years)	Average follow up (months)	Trauma
Scheufler et al.	2005	Germany	6	8	5	11	3	42	3	1 Hockey, 1 tennis, 2 golf, 10 fall and car accident
Xiong et al.	2010	China	3	4	4	NA	NA	27.1	8.4	3 badminton, 1 tennis, 8 golf
Bachoura et al.	2013	USA	0	7	0	7	0	21.7	0.5	7 baseball
Devers et al.	2013	USA	1	12	0	NA	NA	19	1.5	9 baseball, 1 footbal, 1 golf
Tolat et al.	2014	UK	0	7	0	7	0	30.7	2.5	1 golf, 6 unknown
Sarabia et al.	2015	Spain	2	2	0	3	1	32	1–10 years	1 traffic accident, 3 trauma
Guss et al.	2017	USA	0	18 operative intervention		18	0	25.1	3–28 years	18 baseball
Kadar et al.	2017	USA	37	14 operative intervention		NA	NA	34.4	73	17 sports, 25 fall, 3 traffic accident, 6 other
Bansal et al.	2017	USA	NA	NA	NA	74	7	22	96	74 athlete and 7 non-athlete

NA: Data is not available. OFIF: Open reduction and internal fixation.

As the Table 1 showing, in 74 cases the main reason of hamate hook fracture is sports and 33 cases of trauma other than sports. There are 157 males, 25 females and 23 cases not be discerned. The primary etiology of the hamate hook fracture is athletics (74/205,36%), and the second is fall and traffic accident (61/205,30%). In total, the included studies consisted of 205 patients, 44 cases of patients done with excision, 23 cases of patients fixed with ORIF, 40 cases of patients with conservative treatment and 25 cases where the method used could not be discerned. As the Table 2 showing, CT scan is the most used and effective diagnosis tools. Compared to the X-ray group (76/141,53.9%), the accuracy rate of diagnosis by CT was raised in CT scanning group (113/145,77.9%).

Table 2

Diagnostic imaging: Number of positive imaging results/number of imaging performed

Study	X-ray	CT	MRI	Bone scan
Scheufler et al.	9/12(75%)	8/12(67%)	5/12(42%)	NA
Xiong et al.	NA	12/12(100%)	NA	NA
Tolat et al.	2/7(29%)	5/7(71%)	NA	NA
Kadar et al.	5/48(10%)	37/40(92%)	19/19(100%)	10/11(91%)
Bansal et al.	60/74(81%)	51/74(69%)	38/74(51%)	1/74(0.7%)

NA: Data is not available. CT: computerized tomographic. MRI: Magnetic Resonance Imaging.

4. Discussion

Hamulus fractures account for 2% – 4% of all carpal fractures [2, 17]. Within these, fractures involving the hook of the hamate are even less frequent. Most of the occupations of the fracture are cricketers, golfers, tennis players, and rock climbers [17 –19]. In Asia especially in China, these cases are not often reported [20]. The mechanism of injury leading to acute hamulus fracture continues to be an arguable. For this case, no history of severe trauma, ulnar-sided pain and tenderness in young boys must be firstly noted and carefully evaluated. It is predicted that this fracture is caused by a fall on outstretched hands. Fall on an outstretched hand causing sudden forcible dorsi flexion of the wrist, which is associated with severe muscular contraction of the hypothenar intrinsic muscles or the extrinsic flexor tendons of the ring and little fingers, anchored to the hook or by stress upon the pisohamate ligament. It usually fractures the base of the hook. Another reason is a sudden shearing force applied by the flexor tendon of the small finger [21, 22]. It often produces an avulsion of the tip of the hook.

Because of the variable and occult presentation of the fracture, the diagnosis can be challenging. A carpal tunnel view of the wrist, magnetic resonance imaging (MRI), and axial CT scanning can be useful for accurately diagnosing and defining the pattern of the lesion [4 , 23]. Among these diagnosis methods, CT is the best imaging for detecting hamate fractures because of high sensitivity and specificity (100% & 94.4%) [24]. Further, the 3D dynamic videos of target bones can be not only acted as an optimal diagnostic approach for surgery but also be as a better learning tool for residents or medical students. Clinically, patients with hamate fracture have pain and swelling. Radiological diagnosis with postero-anterior and lateral radiographs may not provide adequate images. The hamate hook fracture could be showed on some special slices of the original CT images and noted only by the experienced radiologists. However, with using Mimics software, a trained medical student can easily and accurately define 3D models of lesion for visualization and diagnosis. To the authors’ knowledge, there is no report and study about early diagnosis of the hamate hook fracture with using 3D video method.

With the aid of 3D reconstruction of CT images, we chose the Bruner approach was identical to that described above [25]. The motor branch of the ulnar nerve was identified, protected, and released from the fracture site. The fracture site was cleaned with a dental pick and the fracture was reduced. A cannulated compression screw was inserted under fluoroscopic guidance. The screw was countersink so that the deep motor branch of the ulnar nerve would rest on bone. The extensor tendons were retracted and capsule opened. A guide wire was inserted to the hamate and into the centre of the hook under fluoroscopic guidance. Drilling was performed and the fracture was fixed with two cannulated screws. After 10 months, the fracture was union. The operated hamate bone was evenly union with a good function, grip strength and normal range of motion.

Scheufler had demonstrated nonunion rates greater than 83.3% with conservative treatment [8]. These non-unions are likely multi-factorial, involving poor blood supply, delayed diagnosis, and fragment displacement with continuous movement of the fourth and fifth digits while casted. Therefore, the hamate hook fractures should be referred to a hand surgeon for possible surgical intervention.

5. Conclusion

A review of the literature confirms that CT imaging is the gold standard and essential for diagnosis of hamate fractures. In our case study, we found that three-dimensional(3D) reconstructed images based of CT could provide more accurate and insight illustration for better evaluation in surgical planning.

Funding information

The study was supported by fund from the National Natural Science Foundation of China (Grant No. 81672231).

Footnotes

Acknowledgments

The authors would like to acknowledge Lily Chen for her help in the methodology.

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Diagnosis of a hamate hook fracture with 3D reconstruction of computed tomography images: A case report and review of literature

Abstract

Keywords

1. Introduction

2. Case report

Table 1 Characteristics of included retrospective analysis of studies published in the last 18 years

5. Conclusion

Funding information

Footnotes

Acknowledgments

References

Table 1
Characteristics of included retrospective analysis of studies published in the last 18 years