The Knee 14 (2007) 245–248

Short communication

Acute injury of anterior cruciate ligament during karate training

Kuo-Chin Huang ⁎, Wei-Hsiu Hsu, Ting-Chung Wang

Department of Orthopaedic Surgery and Neurosurgery, Chang Gung Memorial Hospital at Chiayi, Chang Gung University, College of Medicine,6 Sec. West, Chia-Pu Road, Pu-Tz City, Chia-Yi County 613, Taiwan

Received 27 August 2006; received in revised form 29 November 2006; accepted 14 December 2006

Abstract

A 38-year-old black-belt karate practitioner presented with acute disabling injury of his knee after swift-withdrawal of a reverse-roundhouse-kick. Examination confirmed the diagnosis of grade III ACL tear. Although there are reports documenting injury rate in modernkarate, no previous cases of karate-related ACL injuries have been reported. The trauma mechanism is different than ACL injuries duringother non-contact and contact sports. The current case report indicates that ACL injury can occur without any contact of the lower limb as aresult of dynamic muscular forces during karate training.© 2007 Elsevier B.V. All rights reserved.

Keywords: Karate injury; Martial arts; Anterior cruciate ligament

1. Introduction

Injuries involving the anterior cruciate ligament (ACL) ofthe knee joint present major problems to high-demand (level Ior II activities) athletes [1,2] and usually confine them to levelIII and IVactivities only. The ACL may be injured by contact(e.g. lacrosse, ice hockey, gymnastics, football and rugby) ornon-contact (e.g. basketball, competitive badminton, volley-ball, alpine skiing, football and rugby)mechanisms. Injuries ofthe ACL from martial arts, although possible, occur much lessfrequently than in other sports. Shotokan karate is a high-demand activity but a light-contact style of martial arts [3,4].Techniques are pulled just short of contact to the head, and onlytouch contact to the body is permitted [3]. Generally speaking,karate injuries are fairly common but usually minor [5]. Theyare more likely to occur during competitions than whiletraining [6]. Although there are reports documenting injuryrate in modern karate [4–7], no previous cases of ACL injurieshave been reported. The authors report on a black-belt karatepractitioner with acute injury of ACL during training. Thetrauma mechanism is different than those during other non-contact and contact sports and will be discussed in the text.

⁎ Corresponding author. Tel.: +886 5 3621000x2004; fax: +886 5 3623005.E-mail address: kc2672@adm.cgmh.org.tw (K.-C. Huang).

0968-0160/$ - see front matter © 2007 Elsevier B.V. All rights reserved.doi:10.1016/j.knee.2006.12.002

2. Case report

While practicing, a 38-year-old black-belt (4th Dan; BMI25.5 kg/m2; total body fat percentage 17%, by the skin-foldtest) Shotokan karate practitioner without any other prior kneeinjuries attempted to withdraw his right reverse-roundhouse-kick (Fig. 1) just short of contact to the head of opponent (5thDan). He forcefully extended his right knee with concomitantvalgus and internal rotation and then, unexpectedly, felt apainful pop in the knee joint. The injury was disabling and hewas unable to continue playing. He complained of giving wayand observed mild swelling of the lesion knee several hoursafter injury. Due to persistent knee instability and inability ofreturn-to-play, he was referred to our clinic 3 weeks later.

Upon examination, the Lachman test revealed excessiveanterior translation with a soft end point. The positive pivotshift maneuver indicated a torn ACL. Instrumented arthro-metry testing (Compu KT™, MEDmetric Corporation, SanDiego, CA, USA) demonstrated a grade III anterior knee laxitywith maximum manual side-to-side difference of 5.5 mm andconfirmed the diagnosis of grade III ACL tear (Fig. 2A).Plainradiographs revealed no bone lesion. Oblique sagittal T2-weighted MR images showed direct signs of ACL tear,including high-signal intensity at the femoral attachment withthe distal thickened segment extending to the tibia (Fig. 2B).

Fig. 1. Illustration of reverse roundhouse kick. (A) Facing the opponent in a fighting stance. (B) Turning the body around the pivot of the ground-planted foot. (C)Lifting and rotating the leg and early swinging the foot. (D) Swinging the foot across the centerline, leaning the trunk backwards slightly to gain height, and thenkicking in an upward outward motion to the center line target. (E) Retracting the leg by bending the knee and completing a 360° performance. (F) Returning to thefighting stance. Improper swift-withdraw of reverse-roundhouse-kick (extending the knee with concomitant valgus and internal rotation) in the reported case mayhave been a contributing factor to ACL injury. The combination of maximum quadriceps pull, valgus and internal tibial torque would endanger the athlete's ACLand might result in a major functional disability.

246 K.-C. Huang et al. / The Knee 14 (2007) 245–248

To return to high-level sports, the athlete underwent ACLreconstruction for the grade III injury. Arthroscopic findingsrevealed a completely ruptured ACL at the femoral attach-ment. The arthroscopic reconstructive procedure involved acomposite graft with double-looped semitendinosus andgracilis tendons passed through tibial and femoral tunnelsand fixed with at least double fixation. Range of motion,proprioceptive training and isometric exercises were begun theday following surgery. On the 14th day post-surgery, half-squats with a brace were initiated as a closed-kinetic-chainstrengthening exercise. The patient regained the full range ofmotion in his right knee at 6 weeks after surgery. At 3 monthspost-surgery, instrumented arthrometry testing was re-per-formedanddemonstrated side-to-sidedifference at 134newton(N) of 2.5 mm and maximum manual difference of 0.2 mm

(Fig. 2A). The patient was then permitted to return to athletics.One year post-surgery, he did not experience pain or instabilityin this knee during karate training or at other times.

3. Discussion

Although martial art has been introduced as a sport in theWestern Hemisphere recently, there is incredible interest inthis sport and it is one of the fastest growing sports in theUnited States [1]. Many parents regard martial arts as a formof physical activity and discipline for their children, as wellas a tool for self-defense [3,8,9]. Participation in martial arts,therefore, has increased dramatically since the mid-1980swith approximately 8-million Americans involved [3].Shotokan karate is one of the most popular and traditional

Fig. 2. (A) Quantified document of the amount of knee laxity by the instrumented arthrometry testing (Compu KT™, MEDmetric Corporation, Santiago, CA,USA). Before ACL reconstructive surgery, the instrumented arthrometry testing demonstrated a grade III anterior knee laxity (passive displacement at 134 N,12.5 mm) with maximum manual side-to-side difference of 5.5 mm and confirmed the diagnosis of grade III ACL tear. At 3 months after surgery, instrumentedarthrometry testing was re-performed and demonstrated side-to-side difference at 134 N of 2.5 mm and maximum manual difference of 0.2 mm. (B) Obliquesagittal T2-weighted magnetic resonance (MR) image shows direct signs of ACL tear, including high signal intensity at the femoral attachment (arrow) with thedistal thickened segment (asterisk) extending to the tibia.

247K.-C. Huang et al. / The Knee 14 (2007) 245–248

training, consisting the practice of kihon (basic techniques),kata (predetermined combinations of techniques), andkumite (sparring). From the many studies in the literature[4–7], karate is considered a safe sport, with all injuriesbeing extremely minor in nature [5]. The vast majority ofkarate injuries consist of bruising due to incidental contactduring competitions or training.

The ACL is the primary stabilizer for resisting anteriortranslation of the tibia on the femur. It also serves as asecondary stabilizer to resist internal rotation of the tibia onthe femur as well as varus and valgus rotation [1,2,10]. ACLdeficiency leads to combined anterior and rotatory abnormal

laxity, resulting in functional disability. For those high-demand athletes, grade III ACL injury is usually disablingand may be the reason for declination of their career [1,2].Karate is a good example of high-demand athletics. In spar-ring matches, the practitioners face each other within a 2-mdistance, making offensive and defensive behaviors. In theformer, the assailant takes the initiative to make the distanceshorter and to strike or kick rapidly. The defender forestallsthe opponent's actions in order to dodge, block and, sub-sequently, to counter. Therefore, swiftness in the shiftingdisplacement should be an element of performance [8] andthus depends on knee stability. Complete rupture of ACL

248 K.-C. Huang et al. / The Knee 14 (2007) 245–248

would disable the practitioners, block up the path of return-to-play and, eventually, result in declination of their career.

Athletes of the martial arts will frequently jump and landin positions that stress the ACL. Although there were noprevious cases of karate-related ACL injuries in the literature[3–7], the ACL may be injured by non-contact mechanismsimilar to other sports during competitions or training. Inkeeping with the rule of modern karate, there is a greatemphasis on self-improvement; not injuring one's opponentis the highest expression of the martial art [4,5,7]. Whilstsparring, most trained practitioners aim to deliver strikes orkicks with the maximum speed and power possible, but tostop them at the moment of contact so that the opponent isnot injured [3,8]. However, a swift-withdraw of reverse-roundhouse-kick may lay a great stress on the athlete's ACL.The reverse-roundhouse-kick is an attack in which theassailant swings the leg high up in a backward-circular-motion and hooks the heel into the opponent. To avoiddirectly contacting and injuring the opponent, the assailantoccasionally needs to forcefully extend the knee withconcomitant valgus and internal rotation. The combinationof maximum quadriceps pull, valgus and internal tibialtorque would endanger the ACL and result in functionaldisability [1,10]. The mechanism of this injury is somewhatdifferent than previously reported ACL injury mechanisms.Although ACL injuries have been reported in both non-contact and contact sports, this mechanism appears unusualin that there was no contact between the lower limb and astatic object such as another individual or wall. Therefore,the forces necessary to sustain the injury appear to haveoccurred from momentum of the lower extremity andmuscular forces within the lower limb during the karatetraining activity.

The current case demonstrates a rare but significant injuryin a well-trained karate practitioner and that a thorough

understanding of the trauma mechanism may be importantfor prevention. Improper swift-withdraw of reverse-round-house-kick in this case should have been a contributingfactor. Because kicks play a great part in many martial arts,this case highlights the importance of accurate performanceof reverse-roundhouse-kick. During sparring matches,reverse-roundhouse-kick might be prohibited in consideringsafety.

References

[1] Bergfeld JA, Safran MR. Knee-ligaments. In: Safran MR, McKeagDB, Van Camp SP, editors. Manual of sports medicine. Philadelphia:Lippincott-Raven Publishers; 1998.

[2] Daniel DM, Stone ML, Dobson BE, Fithian DC, Rossman DJ,Kaufman KR. Fate of the ACL injured patient: a prospective outcomestudy. Am J Sports Med 1994;22:632–44.

[3] Zetaruk MN, Violan MA, Zurakowski D, Micheli LJ. Injuries inmartial arts: a comparison of five styles. Br J Sports Med 2005;39:29–33.

[4] Critchley GR, Mannion S, Meredith C. Injury rates in Shotokan karate.Br J Sports Med 1999;33:174–7.

[5] Tuominen R. Injuries in national karate competitions in Finland. ScandJ Med Sci Sports 1995;5:44–8.

[6] Arriaza R, Leyes M. Injury profile in competitive karate: prospectiveanalysis of three consecutive world karate championships. Knee SurgSports Traumatol Arthrosc 2005;13:603–7.

[7] Mc Latchie G. Karate and karate injuries. Br J Sports Med1981;15:84–6.

[8] Mori S, Ohtani Y, Imanaka K. Reaction times and anticipatory skills ofkarate athletes. Hum Mov Sci 2002;21:213–30.

[9] Douris P, Chinan A, Gomez M, Aw A, Steffens D, Weiss S. Fitnesslevels of middle aged martial art practitioners. Br J Sports Med2004;38:143–7.

[10] Hsu WH, Fisk JA, Yamamoto Y, Debski RE, Woo SL. Differences intorsional joint stiffness of the knee between genders. A humancadaveric study. Am J Sports Med 2006;34(5):765–70.