radial extracorporeal shock wave therapy ( rswt ) generates pressure waves through the 
 collision of solid bodies1 . there are a few recent 
 reports regarding the effectiveness of extracorporeal shock wave therapy ( eswt ) on 
 neurogenic heterotopic ossification ( ho ) in the lower extremity , but to our knowledge , the 
 use of eswt or rswt to treat neurogenic ho in the upper extremity has not been reported in 
 the literature4 . we report 2 cases of rswt used to treat neurogenic ho in the upper extremities . in both 
 cases , improvements in pain , range of motion ( rom ) , muscle strength , and hand function were 
 observed . each patient gave their written informed consent and agreed to participate in the 
 treatment . this case report was approved by the ethics committee of the sahmyook medical 
 center . a 49-year - old man was admitted to our physical medicine and rehabilitation ( pmr ) 
 department . a subarachnoid hemorrhage ( sa ) occurred 10 months prior to admission and 
 neurogenic ho of the left shoulder and elbow was diagnosed 2 months before his admission . he 
 had been taking disodium etidronate 800  mg per day ( fig . 1.(a ) in case a , bone scan , x - ray , and musculoskeletal ultrasound demonstrate ho in the 
 left shoulder and elbow . arrows indicate the ho 
 sites.ho : heterotropic ossification ; subs : subscapularis ; cp : coracoid process ; un : ulnar 
 nerve ; me : medial epicondyle ; olec : olecranon ) . in spite of the medication , he continued to complain of constant pain , limited rom , 
 muscle weakness , and impaired hand function . rswt was administered to the inferior portion 
 of the coracoid process of the left shoulder and the medial epicondyle ( me ) of the left 
 elbow using ultrasonographic ( usg ) guidance . the target points of rswt were the ho area that 
 could be seen with usg . ( a ) in case a , bone scan , x - ray , and musculoskeletal ultrasound demonstrate ho in the 
 left shoulder and elbow . : heterotropic ossification ; subs : subscapularis ; cp : coracoid process ; un : ulnar 
 nerve ; me : medial epicondyle ; olec : olecranon a 52-year - old man with a 6-month history of hypoxic brain injury was admitted to our pmr 
 and diagnosed with neurogenic ho of the right elbow ( fig . 
 1 ) . rswt was administered to the ho area including the me and olecranon of the 
 right elbow using usg guidance . medications were not subsequently required due to a good 
 response to rswt . in both cases , rswt was administered using the master plus mp 2000 ( storz , 
 tgerwilen , switzerland ) , and the rswt protocol consisted of 3,000 pulses at a frequency of 
 12  hz during each treatment . the intensity level ranged from 25 bars , and it was 
 administered 5 times a week for 4 weeks , a total of 20 treatments . during rswt , all other 
 treatments , including physical and occupational therapy , were continued as usual . both 
 patients were allowed to take previously prescribed oral medications but additional 
 analgesics or antispastic medications were not permitted . pain assessed with the numerical rating scale ( nrs ) , rom , muscle strength assessed with the 
 manual muscle test ( mmt ) , a hand evaluation test , and the jebsen - taylor hand function test 
 were evaluated prior to each treatment , after treatment , and following 1 month of treatment . pain was reduced from 8 to 0 on the nrs , and the patients remained pain - free 
 for 1 month after treatment . in case a , rom of flexion , abduction , adduction , internal rotation , and external rotation 
 of the left shoulder and additionally , flexion of the left elbow was improved and 
 maintained . the mmt result also showed improvement and the improvement was maintained for 1 
 month ( table 1table 1.range of motion , manual muscle test , hand evaluation test and , jebsen - taylor hand 
 function test resultstestcase acase bbeforeafterfollow up upbeforeafterfollow uprange of motion()shoulderflexion 90140 * 145*extension 202020abduction90130 * 130*adduction1020 * 20*internal rotation6070 * 70*external rotation2060 * 60 * elbowflexion 90100 * 100 * 4080 * 85*extensionfullfullfullfullfullfullsupination7070706065 * 80*pronation7060606062 * 80*manual muscle testshoulderflexionfairfair+*fair+*extensionfairgood*good*abductionfairfair+*fair+*horizontal abductionfairfair+*fair+*horizontal adductionfairgood*good*elbow flexionfairgood*good*fairfairfairextensionfairgood*good*fairfairfairhand evaluation test grasp power ( kg)1420 * 18 * 121212lateral pinch ( kg)3.54.5 * 5.5 * 1.52.5 * 2*tripod pinch ( kg)23.0 * 2.5 * 211.5nine - hole pegboard ( sec)30.625.7 * 25.0 * 13865.1 * 58.7*purdue pegboard test ( number ) 1112 * 12 * 03 * 1*jebson - taylor hand function test 
 ( sec)writing55.3445.00 * 43.71*ntntntcard turning9.317.87 * 8.76 * 11.0411.076.9*small common object12.1610.59 * 10.15*nt47.3 * 19.5*feeding13.8112.25 * 10.94*ntnt25*stacking checkers7.134.50 * 4.12*ntntntlarge light object ( sec)5.845.914.81 * 8.125.71 * 6.34*large heavy object ( sec)6.945.78 * 4.63 * 8.697.12 * 5.06*follow up period was 4 weeks . functional testing of hand strength and speed of hand movement showed 
 improvements that were maintained at least for 1 month after the end of treatment ( table 1 ) . follow up period was 4 weeks . improved score ; nt : not testable ; 
 affected side in case b , right elbow flexion , supination , and pronation were improved , the improvements 
 were maintained for 1 month . in contrast to case a , improvement in the mmt result was not 
 seen ( table 1 ) . in the hand function test , the 
 strength of the hand and speed of hand movement improved , and these improvements were 
 maintained at least for 1 month after the end of treatment ( table 1 ) . ho is a complicated and significant medical problem characterized by abnormal growth of 
 bone in soft tissues , commonly around large joints . in its severe form , the condition causes 
 pain , limited rom , and loss of function in the affected joint . neurogenic ho is associated with injuries to the central nervous 
 system , occurs 24 months after a neurological insult , and mainly affects the major synovial 
 joints between spastic muscles6 . primary treatment is a combination of gentle passive rom exercises and bisphosphonate 
 medication , such as disodium etidronate or nonsteroidal anti - inflammatory drugs . surgical 
 excision may be considered for complicated cases , but surgical complications and 
 postoperative recurrence are common4 . eswt has been described in several case reports as a new treatment strategy for neurogenic 
 ho , but it has been restricted to the lower extremities7 . eswt has been shown to promote bone healing in stress fractures , 
 avascular necrosis , and delayed and/or bony nonunion , and it has been widely used for 
 managing the pain of various musculoskeletal conditions8 . eswt consists of a sequence of single sonic pulses characterized by 
 high peak pressure ( 1001,000 bars ) of short duration ( 0.2 s ) and has a focused pressure 
 field with deep penetration depth . compared with eswt , rswt is characterized by 110 bars of pressure of 0.20.5  ms duration 
 and has a radial pressure field with shallow penetration depth . despite the physical 
 differences , the stimulation effects and therapeutic mechanisms of eswt and rswt are almost 
 the same1 . in our cases , pain , rom , muscle strength , and hand function improved although imaging 
 studies with radiographs and bone scans showed no changes . this result is consistent with 
 previous studies that reported improvement in pain and function without changes in imaging 
 studies7 , 8 . based on the results of these studies , it is our opinion that 
 imaging findings do not accurately reflect the pain and function caused by neurogenic 
 ho . the mechanism of pain reduction with eswt or rswt is not well known and there are several 
 hypotheses9 . eswt or rswt generates 
 oscillations in tissue that lead to improvement of microcirculation and metabolic 
 activity1 . immediate pain reduction 
 after eswt could be the result of a hyperstimulation analgesic effect10 . the improvements observed in rom , mmt , and hand function of the present two cases could be 
 associated with pain reduction , since proper management of pain caused by neurogenic ho with 
 rswt could have been the cause of the improvements in rom and hand function . as reported by previous studies , in our cases , the improvements in pain , rom , mmt , and hand 
 function were maintained for 1 month after the rswt treatment7 . the mechanism of the long - term maintenance of the improvements is 
 not known but rswt in the early phase of neurogenic ho is effective at preventing 
 progression . they were the inferior 
 part of the coracoid process of the left shoulder and the me of the left elbow in case a , 
 and the me and olecranon of the right elbow in case b. imaging guidance when administering 
 rswt for treating neurogenic ho could help to correctly focus on the ho site and avoid the 
 other vulnerable structures such as vessels and nerves2 , 10 . in conclusion , rswt improved the pain , rom , and hand function of two patients with upper 
 extremity neurogenic ho . further studies are needed to support these results and to 
 understand the mechanism behind the effectiveness of rswt , as well as to devise a protocol 
 for rswt for neurogenic ho .
[ purpose ] to report the effects of radial extracorporeal shock wave therapy ( rswt ) on 
 heterotopic ossification ( ho ) . 
 [ subjects and methods ] two cases of neurogenic ho in the 
 upper extremity were administered rswt using the master plus mp 2000 ( storz , 
 tgerwilen , switzerland ) and ultrasonographic guidance . the rswt protocol consisted of 
 3,000 pulses at a frequency of 12  hz during each treatment . 
 the intensity level ranged 
 from 25 bars , and it was administered 5 times a week for 4 weeks , a total of 20 
 treatments . 
 [ results ] rswt improved pain , range of motion , and hand function in 2 patients 
 with neurogenic ho in the upper extremity . 
 [ conclusion ] further studies are needed to 
 support these results and to understand the mechanism and to devise the protocol of rswt 
 for neurogenic ho .