Abstract
Hamate fractures can be treated nonoperatively, with the percutaneous Kirschner wire (K-wire) fixation, or with excision of a fractured hook of the hamate. Screw fixation is less popular owing to the risk of iatrogenic ulnar nerve injury. The aim of this study was to present the functional results of patients with hamate fractures treated with headless compression screws (HCS). The primary outcome was the Michigan Hand Outcome Questionnaire (MHOQ) after at least 4 months of follow-up. Nine patients were included in this retrospective cohort study. A median MHOQ total score of 67% was reported (interquartile range [IQR]: 44–76). No complications were found during follow-up. HCS fixation is a safe alternative to treat hamate fractures with good functional outcome. This is a Level IV study.
Keywords: hamate fracture, osteosynthesis, headless compression screws, functional outcome
Hamate fractures are rare injuries and account for 2% of carpal bone fractures. 1 2 Despite being rare in the general population, hamate fractures are frequently diagnosed in athletes, such as baseball players, tennis players, and golfers. 3
Fractures of the hook of the hamate (hamulus) usually occur due to direct trauma, such as a fall on the hand or direct pressure by sports equipment as a golf club. 3 Indirect forces may also cause fractures of the hook of hamate due to the insertions of the flexor digiti minimi brevis muscle, opponens digiti muscle, and flexor carpi ulnaris muscle. Moreover, the pisohamate ligament and the retinaculum flexorum also inserts to the hook of hamate and may likewise cause avulsion fractures. 4
The corpus of the hamate typically fractures due to a direct impact of the fifth and fourth metacarpal during a fist blow. Isolated fractures of the corpus of the hamate bone are even more rare than fractures of the hook of the hamate. 1 Injuries associated with fractures of the corpus of the hamate bone are fracture dislocations of the fourth and fifth carpometacarpal (CMC) joints and fractures of the basis of the fourth and fifth metacarpal bases. 2 5 6
Hamate fractures can be classified according to Milch's classification which distinguishes fractures of the hook of the hamate (type 1) and corpus (types 2a and 2b). Type-1 fractures can be divided into three types as follows: (1) fractures of the tip of the hook of the hamate (type 1), (2) fractures of the middle part of the hook of the hamate (type 2), (3) and fractures at the base of the hook of the hamate (type 3). Corpus fractures can be divided into types 2a and 2b which are coronal and transverse fractures of the corpus, respectively.
Complications of inadequately treated fractures include symptomatic nonunion, avascular necrosis (AVN), and CMC posttraumatic arthritis. 1 2 Four types of AVN are distinguished as total, proximal pole, distal pole, and hamate hook. Blood supply to the hamate bone originates via three nonarticular surfaces which are dorsal, volar, and medial on the base of the hamate hook. The proximal pole of the hamate and the hamate hook are most at risk to AVN, especially when fractures cross the blood supply to either the proximal pole or the hamate hook. 7 8
Nondisplaced fractures of the hook of the hamate can be treated with a short-arm cast for 4 to 6 weeks; however, nonunion rates up to 50% are reported. In case of a displaced fracture of the hook of the hamate, excision is regularly performed. Displaced hamate corpus fractures or nondisplaced hook fractures can be treated with headless compression screws (HCS). 9 However, screw fixation is less popular due to the risk of iatrogenic ulnar nerve injury.
The aim of this study is to present the operative technique and postoperative results of patients treated with HCS for the fixation of hamate fractures.
Methods
Study Population
In this retrospective cohort series, all consecutive adult patients with a hamate fracture, treated with HCS between August 2012 and November 2017, were screened for inclusion. Inclusion criteria were (1) patients with 18 years or older and (2) patients with an acute fracture of the hamate including dislocations fractures of the fourth and fifth metacarpals. Only patients with dislocated corpus fractures or nondisplaced hook fractures were included. Patients with other accompanying traumatic injuries and those with poor understanding of the Dutch or English language were excluded.
Outcomes
Primary outcome of this study was the Michigan Hand Outcome Questionnaire (MHOQ). This questionnaire is composed of several subscales which include overall hand function, functioning on daily activities, functioning on work activities, pain, aesthetics, and satisfaction. The total MHOQ ranges from 0 to 100, where a higher score defines a better hand function. 10 For the subscales, a higher value defines a better hand function. For the subscale pain, this outcome is inversed; a lower score defines less pain and therefore a better hand function. Scores are expressed as percentage of the maximum score. Secondary outcomes were complications, and whether or not patients were able to continue their profession following surgical treatment.
Data Collection
Patient characteristics were obtained from the Electronic Patient Record, HIX (Chipsoft 6.1 HF52.2). Questionnaires (the MHO) were sent to the patients' home address. After receiving the completed questionnaires, patients were contacted by phone to clarify answers and to fill out missing answers. If patients did not return the questionnaires within 2 weeks, they were contacted with a reminder. After three written reminders, patients were listed as “nonresponders.”
Statistical Analysis
Statistical analysis was done using the Statistical Package for the Social Sciences (SPSS) version 21 designed for Microsoft Windows. Normality of the continuous data was tested with the Shapiro–Wilk test. All continuous variables showed an abnormal distribution and were, therefore, displayed as median and percentiles (P 25 –P 75 , interquartile range [IQR]). Owing to the descriptive aspect of this study, no tests for statistically significance were performed.
Ethics
Ethical approval for data collection was obtained from the local ethics committee. All included patients signed an informed consent form.
Surgical Technique
All operations were performed by one senior hand surgeon with an expert level of expertise according to the Tang criteria. 11 In all procedures, a dorsal approach was performed. The dorsal branch of the ulnar nerve was identified and mobilized to allow a safe approach to the hamate. For all cases, the same type of screw was used.
In case of a dislocated corpus of the hamate fracture (in dislocation type of fractures), first reduction of the fracture was performed and, when necessary, an additional antirotation or positioning the Kirschner wire (K-wire; 1 mm) fixation was used. For fixation of a nondisplaced hook fracture no additional measures were taken. With the image intensifier the hook of the hamate was projected in such a way that it was represented by a circle in the posterior–anterior (PA) view. Next, the K-wire of the HCS (Acumed Acutrak 2 micro) was positioned slightly ulnar of the center of the circle and drilled in the direction of the hook of the hamate but not penetrating the far cortex ( Fig. 1 ). The position of the K-wire was checked in PA and lateral fluoroscopic images ( Fig. 2 ). In all cases, the appropriate screw length was determined on the preoperative computed tomography (CT) scan. Next, the HCS screw was positioned over the K-wire ( Figs. 3 and 4 ). When in hamate corpus fractures, there was residual instability of the fracture, an additional corpus screw was inserted in some cases ( Figs. 5 6 7 8 9 ). In case of concomitant injuries, such as a luxation of the fourth and/or fifth CMC joint, the additional K-wires were placed percutaneously ( Fig. 10 ). These K-wires can either be kept in situ till the hamate fractures is completely healed or can be replaced by HCS also.
Fig. 1.
K-wire positioning lateral view on X-ray. K-wire, Kirschner wire.
Fig. 2.
K-wire positioning anteroposterior view on X-ray. Note that the hook of hamate was projected as a circle and the K-wire is positioned slightly ulnar of the center of this circle. K-wire, Kirschner wire.
Fig. 3.
Headless compression screw position anteroposterior view on X-ray.
Fig. 4.
Headless compression screw position lateral view on X-ray.
Fig. 5.
Headless compression screw position transversal view on CT scan. CT, computed tomography.
Fig. 6.
Headless compression screw position anteroposterior view on CT scan. CT, computed tomography.
Fig. 7.
Headless compression screw position sagittal view on CT scan. CT, computed tomography.
Fig. 8.
Two headless compression screw position anteroposterior view on X-ray.
Fig. 9.
Two headless compression screw position lateral view on X-ray.
Fig. 10.
Additional K-wire placement position anteroposterior view on X-ray. K-wire, Kirschner wire.
Results
Patient Characteristics
Fifty-nine patients were screened for eligibility for this study of which 16 patients met the inclusion criteria. Nine patients returned a signed informed consent form and were included in the study for further analysis. For demographics see Table 1 . One patient with a bilateral hamate fracture only had HCS for one of the fractures; the other one was treated nonoperatively. The median time to surgery was 14 days (IQR: 12–34). The median follow-up was 23 months (IQR: 8–42), with a range of 4 to 57 months.
Table 1. Individual baseline characteristics.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | |
|---|---|---|---|---|---|---|---|---|---|
| Gender | Male | Male | Male | Female | Male | Male | Female | Male | Female |
| Age (y) | 21 | 20 | 47 | 61 | 70 | 35 | 56 | 50 | 20 |
| Operated side | Right | Right | Right | Left | Left | Right | Right | Left | Right |
| Dominant side | Right | Right | Left | Right | Right | Left | |||
| Milch's classification | 2A | 2A | 2A | 1-III | 2A | 2A | 2A | 1-II | 2A |
| Associated metacarpal luxation | None | Yes | Yes | None | Yes | Yes | No | Yes | |
| Days till surgery | 14 | 15 | 59 | 40 | 14 | 12 | 12 | 10 | |
| Complications | No | No | No | No | No | No | No | No | No |
| Follow-up (mo) | 27 | 23 | 5 | 4 | 29 | 15 | 57 | 55 | 11 |
Primary Outcome
The median MHOQ score was 67% (IQR: 44–76). Data for individual patients are presented in Table 2 . For the overall hand function, a median score of 60% was reported (IQR: 50–85), for functioning on daily activities a median score of 90% (IQR: 53–98), and on work activities a median score of 68% (IQR: 53–98) was reported. For pain, a lower score indicates a better hand function. The median reported pain score was 60% (IQR: 23–75). For aesthetics, a median score of 25% (IQR: 25–44) and for satisfaction a median score of 79% (IQR: 48–88) was reported.
Table 2. Individual outcome measures.
| 1 (%) | 2 (%) | 3 (%) | 4 (%) | 5 (%) | 6 (%) | 7 (%) | 8 (%) | 9 (%) | |
|---|---|---|---|---|---|---|---|---|---|
| MHOQ total score | 75.5 | 74.6 | 40 | 40.6 | 67.4 | 80.8 | 63.75 | 46.5 | 68.8 |
| Overall hand function | 75 | 80 | 50 | 50 | 60 | 90 | 60 | 50 | 90 |
| Daily activities | 90 | 100 | 25 | 55 | 90 | 100 | 85 | 50 | 95 |
| Work activities | 100 | 70 | 50 | 90 | 100 | 60 | 0 | 65 | |
| Pain | 0 | 85 | 25 | 30 | 60 | 70 | 65% | 20 | 80 |
| Aesthetics | 25 | 25 | 75 | 25 | 25 | 25 | 37.5 | 50 | 25 |
| Satisfaction | 87.5 | 87.5 | 25 | 33.3 | 79.2 | 100 | 75 | 62.5 | 87.5 |
Abbreviation: MHOQ, Michigan Hand Outcome Questionnaire.
Secondary Outcome
No complications were found during follow-up. Especially, no ulnar nerve injuries were found during follow-up. All patients returned to the profession of before the surgery or switched to a different job in the same field.
Discussion
This study presents a relatively new view on internal fixation for hamate fractures and shows that open reduction and internal fixation (ORIF) of hamate fractures using HCSs is safe with good clinical outcomes.
In this retrospective cohort of nine patients, a traumatic fracture of the hamate corpus was treated most frequently. Previous publications, however, mostly describe fractures of the hook of the hamate. The hook of the hamate bone carries the greatest fracture risk, since it protrudes volar and radially. 12 Most authors opt for fracture fragment extirpation in treating hook of hamate fractures, since the blood supply in the watershed area, between the hook of the hamate and corpus, is insufficient in most cases and nonunion of the fracture may occur. 12 To lower the chance of symptomatic pseudoarthrosis, prophylactic screw fixation was used for nondisplaced hook fractures in this study. None of the three treated patients with a hook fracture had a nonunion. This study shows a relatively high percentage of simultaneously occurring dislocation fractures of the fourth and fifth metacarpal, an injury that according to earlier publications is rare. 6
In this study, HCS fixation, using two screws, was only used if intraoperative instability of the fracture of the hamate body was eminent. The use of stabilization with two HCSs was compared with one HCS in scaphoid fractures by Quadlbauer et al. This study shows that for unstable B2-type fractures of the scaphoid bone, the use of two HCSs shows higher union rates and equal clinical outcomes compared with one HCS. 13 However, it is unclear if this will also be the case in hamate fractures. In these patients only one screw can be positioned in the hook of hamate due to the confined space. The other was in these cases much shorter and functioned as an additional compression and antirotation screw for the corpus of the hamate.
Iwata et al described a dorsal buttress plate fixation between hamate and capitate as a fixation method for fracture dislocations of the fifth CMC joint. 14
Limitations
One of the limitations of this study is the relatively small study population. However, since hamate fractures are a rare injury, we feel that this cohort is an adequate presentation of the frequency of the injury in a single-medical center. Second, the response rate in this study was low, about 56%. The patients who did not respond were in their early 20's. Therefore, we believe the majority of these patients moved out of the region or had a change in contact details. Besides that, we believe, however, that since these patients were no longer in medical follow-up, no clinically significant postoperative complications occurred. Therefore, we believe that the MHO would have been higher if the response rate was higher. Another limitation is the retrospective design of this study, due to which no conclusions can be drawn about the inferiority or superiority of HCS treatment compared with extirpation of the hook of the hamate. Besides the fact that extirpation of the bone mostly is performed in case of fracture of the hook of the hamate and this cohort composes mostly corpus fractures, proving superiority or inferiority of this treatment was outside the scope of this study. Furthermore, this study has a large range in follow-up, due to which long-term and short-term functional outcome are reported at the same moment. No differences in short- or long-term functional outcome could be drawn from this study.
Conclusion
Operative treatment of fractures of the hamate is a matter of controversy. We tend to treat all acute hamate fractures surgically. Inadequate treatment of these fractures may result in symptomatic nonunion which can cause compression on the ulnar nerve and flexor tendons of the fourth and fifth digits. 3 12 Compression can result in morbidity and reduced hand function due to pain, weakened grip, and paresthesias in case of ulnar compression. 12 Furthermore, direct anatomic restoration of the integrity of the articular surface of the hamate bone restores the dislocation of the metacarpalia and may prevent symptomatic arthritis of the CMC joint. This is why, in our opinion, screw fixation should be considered in case of an acute hamate fracture. Open reduction and internal fixation with use of HCS, as described in this manuscript, is a safe procedure with good clinical outcomes for acute dislocated hamate corpus fractures and nondisplaced fractures of the hook of the hamate bone.
Footnotes
Conflict of Interest None declared.
References
- 1.Suh N, Ek E T, Wolfe S W.Carpal fractures J Hand Surg Am 20143904785–791., quiz 791 [DOI] [PubMed] [Google Scholar]
- 2.Cecava N D, Finn M F, Mansfield L T. Subtle radiographic signs of hamate body fracture: a diagnosis not to miss in the emergency department. Emerg Radiol. 2017;24(06):689–695. doi: 10.1007/s10140-017-1523-5. [DOI] [PubMed] [Google Scholar]
- 3.Kadar A, Bishop A T, Suchyta M A, Moran S L. Diagnosis and management of hook of hamate fractures. J Hand Surg Eur Vol. 2018;43(05):539–545. doi: 10.1177/1753193417729603. [DOI] [PubMed] [Google Scholar]
- 4.Scheufler O, Andresen R, Radmer S, Erdmann D, Exner K, Germann G. Hook of hamate fractures: critical evaluation of different therapeutic procedures. Plast Reconstr Surg. 2005;115(02):488–497. doi: 10.1097/01.prs.0000149480.25248.20. [DOI] [PubMed] [Google Scholar]
- 5.Cano Gala C, Pescador Hernandez D, Rendon Diaz D A, Lopez Olmedo J, Blanco Blanco J. Fracture of the body of hamate associated with a fracture of the base of fourth metacarpal: A case report and review of literature of the last 20 years. International journal of surgery case reports. 2013;4(05):442–445. doi: 10.1016/j.ijscr.2013.01.023. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Brinkman J N, Hartholt K A, de Vries M R.Multiple carpometacarpal dislocations and an associated fracture of the hamate: an uncommon injuryBMJ Case Reports2016. 2016 [DOI] [PMC free article] [PubMed]
- 7.Failla J M. Hook of hamate vascularity: vulnerability to osteonecrosis and nonunion. J Hand Surg Am. 1993;18(06):1075–1079. doi: 10.1016/0363-5023(93)90405-R. [DOI] [PubMed] [Google Scholar]
- 8.Peters S J, Verstappen C, Degreef I, Smet L D. Avascular necrosis of the hamate: three cases and review of the literature. J Wrist Surg. 2014;3(04):269–274. doi: 10.1055/s-0034-1394135. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Snoap T, Habeck J, Ruiter T. Hamate fracture. Eplasty. 2015;15:ic28. [PMC free article] [PubMed] [Google Scholar]
- 10.Chung K C, Pillsbury M S, Walters M R, Hayward R A. Reliability and validity testing of the michigan hand outcomes questionnaire. J Hand Surg Am. 1998;23(04):575–587. doi: 10.1016/S0363-5023(98)80042-7. [DOI] [PubMed] [Google Scholar]
- 11.Tang J B, Giddins G. Why and how to report surgeons' levels of expertise. J Hand Surg Eur Vol. 2016;41(04):365–366. doi: 10.1177/1753193416641590. [DOI] [PubMed] [Google Scholar]
- 12.Bansal A, Carlan D, Moley J, Goodson H, Goldfarb C A. Return to play and complications after hook of the hamate fracture surgery. J Hand Surg Am. 2017;42(10):803–809. doi: 10.1016/j.jhsa.2017.06.108. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Quadlbauer S, Beer T, Pezzei C et al. Stabilization of scaphoid type B2 fractures with one or two headless compression screws. Arch Orthop Trauma Surg. 2017;137(11):1587–1595. doi: 10.1007/s00402-017-2786-8. [DOI] [PubMed] [Google Scholar]
- 14.Iwata N, Komura S, Hirakawa A et al. Dorsal buttress plate fixation for the treatment of fracture-dislocation of the fifth carpometacarpal joint with avulsion fracture of the hamate: a case report. Arch Orthop Trauma Surg. 2019;139(01):135–139. doi: 10.1007/s00402-018-3072-0. [DOI] [PubMed] [Google Scholar]