RESEARCH ARTICLE Open Access

Surgical treatment of avulsion fracturearound joints of extremities using hookplate fixationQudong Yin1†, Yongjun Rui1†, Yongwei Wu1*, Jun Liu1, Yunhong Ma1, Sanjun Gu1, Mingxia Zhou1 and Jiwen Yu2

Abstract

Purpose: This study proposed to access the clinical outcome of avulsion fractures around joints of extremities usingthe hook plate.

Methods: A total of 60 patients with avulsion fractures of joints admitted in our hospital between January 2011 andJune 2016 were performed the surgery of hook plate fixation. Functional recovery was evaluated using the Lysholmknee score, Kaikkonen ankle injury score, Mayo elbow and wrist function score, and Neer shoulder function score.

Results: All the patients were healed within 3 months after surgery with stage I healing incision without vascular ornerve injuries. The average follow-up period was 18.1 months. At the last follow-up, no instability of joints, looseness ofinternal fixation or traumatic arthritis was observed. Mild joint fibrosis occurred in 5 cases. A total of 57 patients werewell recovered with the excellent and good rate of 95%. Three patients with humeral avulsion fracture of the greatertuberosity had shoulder joint adhesion and peri humeral inflammation at the last follow-up due to the poor cooperationfor early rehabilitation exercise. In the last follow-ups, the functional score of the affected limb was markedly greater thanthat in the 3-month follow-ups (p < 0.05).

Conclusion: Hook plate fixation has the therapeutic effect on treating avulsion fractures around joints of extremities withthe advantages of reliable fixation, early rehabilitation after operation, high recovery rates of joint function, wide indications,and convenient uses.

Keywords: Avulsion fractures, Hook plate, Internal fixation

IntroductionJoints are surrounded by articular capsule, ligaments andtendons. Avulsion fractures occur when the capsule,ligaments or tendons are avulsed from the bone due tounexpected contraction of the muscles or mechanicalforce [1]. As reported, the contractile properties ofmuscle and the attachment of tendons and ligaments atboth ends of bone collectively contributed to the musclecontraction, so unexpected contraction of the musclescould lead to avulsion fractures at the site of tendon orligament attachment [2]. Most avulsion fractures wereintra-articular fractures, while relatively small fracture

fragments are commonly attached to the ligament andcapsule, making the joint difficult to return to the nor-mal anatomical position [3]. The conservative treatmentoften has a poor therapeutic effect on avulsion fracturesaround joints, easily leading to fracture nonunion, jointinstability and joint adhesion [4]. There are several fixa-tions used to treat avulsion fractures, mainly includingscrew fixation [5], percutaneous Kirschner wire (K-wire)fixation [6], bone grafting [7], and plating fixation [8].Internal fixation using lag screws or absorbable screws isrecommended to fix large fragments, while K-wire andstainless-steel wire fixation is used to fix small fragmentsin order to avoid fracture nonunion [9]. However, thestability of screw fixation was not sufficient to meet therequirement of early rehabilitation exercise for patientswith osteoporosis [10]. K-wire and stainless-steel wirefixation also shows unfavorable outcome, such as poor

© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

* Correspondence: 13665150065@126.com†Qudong Yin and Yongjun Rui contributed equally to this work.1Department of Orthopaedics, Wuxi No. 9 People’s Hospital Affiliated toSoochow University, No.999 Liangxi Rd, Wuxi 214062, Jiangsu Province,People’s Republic of ChinaFull list of author information is available at the end of the article

Yin et al. BMC Musculoskeletal Disorders (2019) 20:200 https://doi.org/10.1186/s12891-019-2585-1

stability of the joint, which increases the risk of internalfixation failure.Recently, accumulating evidence has strongly implied

that the hook plate fixation has the advantages of morestable fixation of the fragments regardless of the bonequality and high accurate reduction in fracture withsmall fragments in the treatment of avulsion fractures[11]. For example, Shin et al. [12] found that the hookplate fixation provided stronger fixation relative to asuture anchor for thumb ulnar collateral ligament (UCL)fracture-avulsions. Moreover, Mehling et al. [13] havereported the excellent outcomes of mini-hook platetreating for phalangeal fractures. Based on these find-ings, we proposed that the hook plate might be a com-patible fixation instrument for treating avulsion fracturesaround joints.The purpose of the present study was to summarize

clinical data of patients with avulsion fractures aroundjoints of the extremities treated with hook plate fixation.More importantly, it was our goal to assess the necessityof surgery, the flaw of the mainstream internal fixationas well as the specific characteristics and therapeuticoutcomes of hook plate.

Material and methodsParticipantsA total of 60 patients who met the criteria wererecruited for this study from January 2011 to June 2016.Inclusion criteria: (1) Avulsion fractures that were fit forthe treatment of hook plate fixation, including the frac-tures of the humeral greater tuberosity, humeral condyle,ulna olecranon, ulnar styloid, ankle joint, and tibial con-dyle. (2) The width of the avulsed fracture bone isgreater than 10mm, which is larger than the opening ofthe hook plate. (3) The fracture separative shift shown inCT scan or X-ray is more than 5mm. (4) Follow-up datawere completed. Exclusion criteria: (1) Patients withconcurrent severe fractures or vascular and nerve injuryat the same joint, (2) The follow-up time was less than12months, (3) less than 18 years old.There were 35 males and 25 females aged between 20

and 73 years (mean age 43.7). The causes of fracture in-cluded fall injury (n = 24), sports related injury (n = 17),

falling injury (n = 11), and traffic injury (n = 8). Of the 60patients, 19 cases were avulsion fractures of posteriorcruciate ligament (PCL) at the tibial insertion, 6 caseswere avulsion fracture of the humeral medial epicondyle,8 cases were avulsion fractures of the humeral greatertuberosity, 6 cases were lateral malleolus avulsion frac-tures, 17 cases were ulna olecranon avulsion fractures,and 4 cases were ulnar styloid avulsion fractures. Allfractures were fresh and unstable fractures. All patientspresented to the clinic between 2 h to 19 days with themean day of 6.6 days after injury. To confirm the diag-nosis of avulsion fractures, patients received X-ray,

Table 1 The general information of the patients

Fracture Site Case Gender (m/f) Age Hospital stays (days) Preoperative Functional Score

Greater tuberosity of humerus 8 5/3 54.8 ± 19.1 6.9 ± 1.4 42.0 ± 2.1

Medial epicondyle of humerus 6 4/2 27.8 ± 7.7 6.0 ± 1.4 50.5 ± 1.9

Ulna olecranon 17 10/7 43.8 ± 13.8 7.6 ± 3.0 48.4 ± 1.9

Ulnar styloid 4 4/2 42.8 ± 12.7 5.5 ± 0.6 55.5 ± 2.1

Lateral malleolus of tibia 6 3/3 42.0 ± 14.2 6.7 ± 4.4 50.5 ± 2.1

Knee PCL 19 11/8 45.4 ± 14.5 6.4 ± 1.4 50.2 ± 1.4

PCL posterior cruciate ligament

Fig. 1 Diagram of hook plates with two symmetric sharp teeth hooks

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computed tomography (CT) or/and Magnetic resonanceimaging (MRI) examination. The general information ofthe patients was shown in Table 1.

Operative techniqueThe operation was performed in all patients under gen-eral anesthesia. The hook plates used in this study wereAO hook plates (n = 21) or 1/3 titanium plates (n = 39)with two symmetric sharp teeth hooks, as shown inFig. 1. After the removal of soft tissues at broken ends,bones were provisionally fixed with Kirschner wiresprior to placing hook plates. Subsequently, hook plateswere reconstructed to anastomose the bone surface ac-cording to inserted location and anatomical features ofbones. The well-reconstructed hook plates were placedon the bone surface with sharp teeth-hooks fixed in themiddle of the attachment points of ligament or tendon.Afterward, the hook surface was gently clicked to stickto fracture fragments. The Interventional C-Arm X-Rayimaging was used to confirm whether the bones weresatisfactorily recovered and the hook plates were

well-located. A cortical screw was passed through fromthe hole of hook plates for compressive fixation, whileanother cortical screw was inserted to maintain the re-duction. In addition, the other cortical screw could beused to fix the greater fracture fragments by passingthrough from the crotch or lateral of the two hooks. Asshown in Figs. 2, 3 and 4, the fragments of avulsion frac-tures were fixed by a hook plate or/and a screw. Afterthe stability of remaining fracture fragments was main-tained during continuous passive motion, negative pres-sure drainage was put and the skin was sutured.

Postoperative care and functional evaluationThe limbs were treated with the assistance of continuouspressure by elastic bandages within 2 days post oper-ation. Functional rehabilitation training began afteranesthesia failure. One week postoperatively, patientswith avulsion fractures of lower limb ligaments were en-couraged to do some gentle exercise in the case of wear-ing the orthosis. From the 8th week, a free motion andweight bearing were allowed without orthosis. However,

Fig. 2 The radiographs of patients with ulnar styloid avulsion fracture treated with hook plate fixation. a The illustrations showing the hook plateprocedure; (b) Preoperative posteroanterior X-ray films; (c) Lateral X-ray films after 3 months postoperatively

Fig. 3 The radiographs of patients with avulsion fractures of PCL at the tibial insertion treated with hook plate fixation. a Preoperativelateral X-ray films and CT three-dimensional (3D) reconstruction; (b) Diagram of hook plate fixation; (c) Posteroanterior and lateral X-rayfilms after 3 months postoperatively

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on the third day after surgery, patients with avulsionfractures of upper limbs were allowed to do recovery ex-ercise without orthosis. All of the patients were reviewedand examined monthly after the operation and every 2–3 months after fracture union. One year later, the reviewperiod was changed to every 6 months. At the finalfollow-up, the functional recovery was assessed usingthe Lysholm knee scores [14], Kaikkonen ankle injuryscores [15], Mayo elbow and wrist function scores [16],and Neer shoulder function scores [17].

Statistical analysisStatistical significance levels were determined by two-tailedt test or one-way analysis of variance (ANOVA). The pvalues of < 0.05 were considered significant. Data were pre-sented as mean ± standard deviation (SD), and were ana-lyzed using SPSS software (version 20.0; Chicago, IL, USA).

ResultsAll the patients were healed within 3 months after sur-gery with stage I healing incision without vascular ornerve injuries. The mean duration of follow-up was 18.1months (range from 12 to 24 months). The functionalscore of the affected limb was significantly improved 3

months after surgery (Table 2, p < 0.05). No fractureswith dislocation or delayed union were found in all pa-tients. In the last follow-up, 3 cases (average age 55) withavulsion fractures of the humeral greater tuberosity hadshoulder joint adhesion and peri humeral inflammation,and the functional recovery of shoulder joint was poor.Other patients were scored excellent or good of thefunctional recovery results. The total excellent and goodrate was 95%. In addition, no instability of joints, loose-ness of internal fixation or traumatic arthritis was ob-served. Mild joint fibrosis occurred in 5 cases. In the lastfollow-ups, the functional score of the affected limb wasmarkedly greater than that in the 3-month follow-ups(Table 2, p < 0.05). Internal fixation was removed afterone year of surgery in 35 patients. The follow-up datafor functional scores at each site was shown in Table 2.Typical cases were presented in Figs. 2, 3, 4, 5 and 6.

DiscussionAvulsion fracture around joints is a form of ligament ortendon injury, and is also a special type of intra-articularfracture [18, 19]. On the one hand, the traction of liga-ments, tendons, or articular capsules increased theoccurrence of displacement. On the other hand, soft

Fig. 4 The radiographs of patients with lateral malleolus avulsion fracture treated with hook plate fixation. a Preoperative CT 3D reconstruction;(b) Diagram of hook plate fixation; (c) Posteroanterior and lateral X-ray films after 3 months postoperatively

Table 2 The follow-up data for functional scores at each site

Fracture site Case Functional score

Preoperation 3 months post operation Last follow-ups

Greater tuberosity of humerus 8 42.0 ± 2.1 67.9 ± 5.5* 84.8 ± 6.3#

Medial epicondyle of humerus 6 50.5 ± 1.9 73.8 ± 2.9* 92.3 ± 1.6#

Ulna olecranon 17 48.4 ± 1.9 70.5 ± 2.9* 90.7 ± 1.6#

Ulnar styloid 4 55.5 ± 2.1 79.0 ± 1.0* 91.5 ± 1.3#

Lateral malleolus of tibia 6 50.5 ± 2.1 72.5 ± 1.9* 92.0 ± 1.4#

Knee PCL 19 50.2 ± 1.4 70.0 ± 1.7* 91.4 ± 1.9#

*p < 0.05 vs. Preoperation; #p < 0.05 vs. 3 months post operation. PCL: posterior cruciate ligament

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tissues are often embedded in the broken end. Thesetwo points make the fracture reduction become diffi-cult, increasing the incidence of nonunion and affect-ing the functional recovery of ligaments, tendons andjoints [12, 13]. Additionally, patients with defects ofarticular cartilage or articular surface would suffer fromarthritis or joint dysfunction. Commonly, conservativetreatment and surgery are the two major treatments ofavulsion fracture. However, conservative treatment oftencauses some complications, such as synarthrophysis, non-union, joint instability, and arthritis, resulting in an un-stable fixation and an unsatisfactory outcome. Therefore,most avulsion fracture is recommended to be treatedwith internal fixation in the early stage. Indeed, patientswith avulsion fractures without displacement was sug-gested to receive surgical treatment to promote thefunctional recovery [13, 14]. For instance, Huang et al.

[19] found that the anterior arthroscopic-assisted fixationwas a simple and feasible alternative for treating PCLavulsion fractures.At present, the commonly used internal fixation

methods for avulsion fracture include screws, steel wires,K-wire tension band, suture anchors, sutures, straddlenails, and allogeneic bone nails, among which screw fix-ation is the most commonly used. The stability of screwfixation is reliable for larger avulsion fracture fragments,but for patients with osteoporosis, small fracture frag-ments, or severe comminution, it is easy to damage thebone fragments when drilling or screwing. Therefore,screw fixation is more suitable for avulsion fracturepatients with large bone mass and without heavy osteo-porosis [18, 20]. For comminuted fractures that cannotbe fixed with screw, steel wires, K-wire tension band,and sutures can be selected. However, these operationsneed to be performed in the transitional zone betweenthe fragment and ligament, which is inconvenient andrelatively cumbersome. When fixing with fine stainless-steelwire, excessive tension will injure ligaments and damagefracture fragments.The hook plate used in surgical treatment of avulsion

fractures had several advantages as follows [1, 13, 21] Itwas established from AO special hook plate or 1/3 titan-ium plate, which was commonly used in fracture treat-ments. (2) The hook plates established a non-rigid fixationto maintain stability, allowing a longer period for retentionof the implant. (3) Eccentric screws were implanted inde-pendent of fracture fragments through the hook plates forcompress fixation. (4) The hook plates declined boringand cutting damages of fracture fragments in favor ofbone union. (5) The hook plates were performed regard-less of the size of ligaments, tendons and fragments. (6) Ithad wide indications, particularly for hand avulsion frac-ture. In addition, Shin et al. [12] compared the mechanical

Fig. 5 The radiographs of patients with left olecranon avulsion fracture treated with hook plate fixation. a Preoperative lateral X-ray films; bPosteroanterior and lateral X-ray films after 3 months postoperatively

Fig. 6 The radiographs of patients with avulsion fractures of greatertuberosity of humerus treated with hook plate fixation. aPreoperative posteroanterior X-ray films; (b) Posteroanterior X-rayfilms after 3 months postoperatively

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effects of the hook plate and the rivet fixation in the treat-ment of ulnar collateral ligament avulsion fracture ofmetacarpophalangeal joint, and the results showed thatthe stability and strength of the hook plate were betterthan the rivet. Our previous research compared hook platewith traditional method in the treatment of avulsion frac-ture of the olecranon, and found that all fractures healed.There was no significant difference in healing time andincidence of complications between the two groups (P >0.05). However, the former was superior to the controlgroup in terms of functional recovery and range of jointactivity, and the difference was statistically significant (P <0.05) [22].In this study, 3 cases with avulsion fractures of greater

tuberosity of humerus had shoulder joint adhesion andperihumeral inflammation, and the functional recoveryof shoulder was poor. One reason is due to the high ageof the patients (average age was 55). In addition, thepatients did not actively cooperate with the treatmentfor early rehabilitation exercises because of their low re-quirements for shoulder joint function after the oper-ation. Meanwhile, the hook is located above the greatertubercle, which may impact the acromion and affectshoulder joint activity. Therefore, anchor suture andfixation should be the first choice for avulsion fractureof greater tubercle of humerus. Our study was designedto evaluate the outcomes of the hook plate fixation for60 patients with avulsion fractures around joints. All thepatients performed early rehabilitation exercises and theincision healed well without complications, such asscrew loosening, instability of joints and arthritis. Theexcellent and good rate of joint function recovery wasabout 95%, which was higher than traditional internalfixation [12]. Nevertheless, hook plate fixation still hadsome limitations. Firstly, hook plate fixation cannot beused under arthroscope. Secondly, it was unsuitable forsevere comminuted fractures and anterior cruciate liga-ment avulsion fractures. Consequently, we shouldchoose the appropriate internal fixation method accord-ing to different clinical situations.In conclusion, hook plate fixation has the therapeutic

effect on treating avulsion fractures around joints withthe advantages of reliable fixation, early rehabilitationafter operation, high recovery rates of joint function,wide indications, and convenient uses.

AbbreviationsCT: Computed tomography; MRI: Magnetic resonance imaging; PCL: posteriorcruciate ligament; UCL: ulnar collateral ligament

AcknowledgementsNot applicable.

FundingNone.

Availability of data and materialsNot applicable.

Authors’ contributionsQY conceived and designed the study and drafted the manuscript. YR andYW put forward the concept of the study and reviewed the manuscript. JLcollected the data and analyzed them. MZ and JY interpreted the data. YMand SG revised the manuscript. All authors read and approved the finalmanuscript.

Ethics approval and consent to participateThe study was approved by the ethics committee of Wuxi No.9 People’sHospital Affiliated to Soochow University. All the individuals wereparticipating in this study with written informed consent.

Consent for publicationNot applicable.

Competing interestsThe authors declare that they have no competing interests.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims inpublished maps and institutional affiliations.

Author details1Department of Orthopaedics, Wuxi No. 9 People’s Hospital Affiliated toSoochow University, No.999 Liangxi Rd, Wuxi 214062, Jiangsu Province,People’s Republic of China. 2Department of Orthopaedics, LianyungangPeople’s Hospital, Lianyungang 222002, China.

Received: 22 February 2018 Accepted: 23 April 2019

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