Ajsm298109.qxd

Extracorporeal Shockwave for Chronic Patellar Tendinopathy
Ching-Jen Wang, Jih-Yang Ko, Yi-Sheng Chan, Lin-Hsiu Weng and Shan-Lin Hsu 2007; 35; 972 originally published online Feb 16, 2007; The online version of this article can be found at: http://ajs.sagepub.com/cgi/content/abstract/35/6/972 Additional services and information for
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American Journal of Sports Medicine
(this article cites 34 articles hosted on the Citations
SAGE Journals Online and HighWire Press platforms): 2007 American Orthopaedic Society for Sports Medicine. All rights reserved. Not for commercial use or unauthorized distribution.
Extracorporeal Shockwave for Chronic
Patellar Tendinopathy
Ching-Jen Wang,*† MD, Jih-Yang Ko,† MD, Yi-Sheng Chan,‡ MD,Lin-Hsiu Weng,† MD, and Shan-Lin Hsu,† MDFrom the †Department of Orthopedic Surgery, Chang Gung Memorial Hospital,Chang Gung University College of Medicine, Kaohsiung, Taiwan, andthe ‡Department of Orthopedic Surgery, Chang Gung Memorial Hospital,Chang Gung University College of Medicine, Taoyuan, Taiwan Background: Chronic patellar tendinopathy is an overuse syndrome with pathologic changes similar to tendinopathies of the
shoulder, elbow, and heel. Extracorporeal shockwave was shown effective in many tendinopathies.
Hypothesis: Extracorporeal shockwave therapy may be more effective than conservative treatment for chronic patellar
tendinopathy.
Study Design: Randomized controlled clinical trial; Level of evidence, 2.
Methods: This study consisted of 27 patients (30 knees) in the study group and 23 patients (24 knees) in the control group. In
the study group, patients were treated with 1500 impulses of extracorporeal shockwave at 14 KV (equivalent to 0.18 mJ/mm²
energy flux density) to the affected knee at a single session. Patients in the control group were treated with conservative treat-
ments including nonsteroidal anti-inflammatory drugs, physiotherapy, exercise program, and the use of a knee strap. The eval-
uation parameters included pain score, Victorian Institute of Sports Assessment score, and ultrasonographic examination at 1,
3, 6, and 12 months and then once a year.
Results: At the 2- to 3-year follow-up, the overall results for the study group were 43% excellent, 47% good, 10% fair, and none
poor. For the control group, the results were none excellent, 50% good, 25% fair, and 25% poor. The mean Victorian Institute of
Sports Assessment scores were 42.57 ± 10.22 and 39.25 ± 10.85, respectively, before treatment (P = .129) and 92.0 ± 10.17 and
41.04 ± 10.96, respectively, after treatment (P < .001). Satisfactory results were observed in 90% of the study group versus 50%
of the control group (P < .001). Recurrence of symptoms occurred in 13% of the study group and 50% of the control group
(P = .014). Ultrasonographic examination showed a significant increase in the vascularity of the patellar tendon and a trend of
reduction in the patellar tendon thickness after shockwave treatment compared with conservative treatments. However, no sig-
nificant difference in the appearance, arrangement, and homogeneity of tendon fibers was noted between the 2 groups. There
were no systemic or local complications or device-related problems.
Conclusion: Extracorporeal shockwave therapy appeared to be more effective and safer than traditional conservative treatments
in the management of patients with chronic patellar tendinopathy.
Keywords: patellar; tendinopathy; chronic; shockwave; conservative treatment
Patellar tendinopathy is a common orthopaedic problem in activities that require repetitive knee extension and flex- characterized by pain and tenderness just below or, less ion, the patellar tendon can develop microtears at the commonly, above the patella.1,6,34 With an increase in fre- attachment site to the inferior pole of the patella. The quency, duration, and intensity of quadriceps contraction pathologic changes seen in this condition are similar tothose of other overuse injuries, including lateral epicondyli-tis (tennis elbow) or plantar fasciitis (painful heel syn- *Address correspondence to Ching-Jen Wang, MD, Department of drome).8,11,12 Conservative treatments have been proposed Orthopedic Surgery, Chang Gung Memorial Hospital, Chang GungUniversity College of Medicine, 123 Ta-Pei Road, Niao-Sung Hsiang, as the initial choice for patellar tendinopathy, including ces- Kaohsiung, Taiwan 833 (e-mail: w281211@adm.cgmh.org.tw).
sation of the offending activity until symptoms subside; No potential conflict of interest declared.
stretching and strengthening exercises for the quadriceps,hamstrings, and patellar tendon; applying heat before and The American Journal of Sports Medicine, Vol. 35, No. 6DOI: 10.1177/0363546506298109 ice after exercise; the use of nonsteroidal anti-inflammatory 2007 American Orthopaedic Society for Sports Medicine drugs (NSAIDs); and the use of a patellar strap to reduce 2007 American Orthopaedic Society for Sports Medicine. All rights reserved. Not for commercial use or unauthorized distribution.
Extracorporeal Shockwave for Chronic Patellar Tendinopathy stress on the patellar tendon. The results of conservative 3. Patients with diabetes mellitus, occlusive vascular treatment have been irregular and inconsistent, and the disease, collagen disease, osteoarthritis or rheuma- symptoms frequently recur.1,4 Surgery has been suggested toid arthritis, coagulopathy, or infection as the alternative method of treatment for severe cases 4. Patients with radiographic fractures around the knee that do not respond to conservative treatments. However, 5. Patients with cardiac arrhythmia or cardiac pace- the results of surgery are unpredictable, and it is associ- ated with surgical risks and complications.5,7,19 Recently, extracorporeal shockwave has been shown The Institutional Review Board of our hospital approved effective in alleviating pain and restoring function attrib- this study. All patients were required to sign an informed utable to tendinopathies of the shoulder, elbow, and heel consent form before study participation. Between October and for promoting bone healing.16,20,21,23-28,31,33 The clinical 2001 and May 2005, 53 patients with 58 injured knees results showed approximately 90% good or excellent were initially assessed for eligibility and enrolled in the results with 5% to 7% recurrence rate in shoulder, elbow, study. Patients were randomly divided into 2 groups by and heel and 80% success in nonunions of long bone frac- assigning patients with an odd medical record number to tures.3,13,26,27,31,33 In animal experiments, some studies the study group and patients with an even number to the reported that shockwave therapy significantly decreased control group. During the course of treatment, 3 patients (4 the nonmyelinated sensory fibers and loss of calcitonin knees) were lost to follow-up and were excluded from the gene-related peptide and reduction in substance P study. The remaining 50 patients (54 knees) completed the release.15,18 Others demonstrated that shockwave stimu- analyses in this study. The flow diagram of patient recruit- lates the ingrowth of neovascularization at the tendon- ment is shown in Figure 1. The study group consisted of 27 bone junction and in bone.29,30,32 Because the pathologic patients (30 knees) and the control group of 23 patients (24 changes of patellar tendinopathy are similar to other over- knees). Three patients in the study group and 1 patient in use injuries, including tennis elbow and plantar fasci- the control group were treated for bilateral knee injuries.
itis,11,12 we hypothesized that shockwave treatment may Patellar tendinopathy involved the proximal end of the produce similar results in patients with patellar patellar tendon in all knees. The average duration of the tendinopathy. The purpose of this study was to evaluate disease was 16.2 ± 17.2 months (range, 6-64 months) ver- the efficacy and safety of shockwave treatment and to com- sus 11.3 ± 10.9 months (range, 6-46 months), and the aver- pare the result with that of conservative treatment for age follow-up was 32.7 ± 10.8 months (range, 10-53 patients with chronic patellar tendinopathy.
months) versus 28.6 ± 9.8 months (range, 10-48 months)for the study group and the control group, respectively.
Some patients were initially treated at another institutionand subsequently referred to our hospital, whereas others Chronic patellar tendinopathy is defined as recurrent pain came to our outpatient clinic at the onset of symptoms. The and tenderness attributable to degenerative changes of the duration of the disease included the time while patients patellar tendon for at least 6 months. The inclusion and were treated elsewhere, whereas the length of follow-up exclusion patient selection criteria are shown below.
only included the time of treatment at our hospital. Therewere 29 recreational athletes including 15 in the study group and 14 in the control group. Their sports and num-bers of participants were 9 basketball, 2 jogging, 2 hand- 1. Patients with a diagnosis of chronic patellar ball, 1 weight lifting, and 1 wrestling for the study group, tendinopathy established by medical history and and 8 basketball, 2 jogging, 2 handball, 1 weight lifting, and 1 wrestling for the control group. The patient demo- 2. Patients who experienced pain of 5.0 or greater on graphic characteristics are summarized in Table 1.
a 0-to-10 visual analog scale while walking up and Patients in the study group received shockwave treatment as outpatients with no local or regional anesthesia. The 3. Patients who understood and complied with the source of shockwave was from an OssaTron (High Medical Technology, Kreuzlingen, Switzerland). Each knee was 4. Patients who were 21 years and older and skele- treated with 1500 impulses of shockwave at 14 KV (equiva- lent to 0.18 mJ/mm² energy flux density) in a single session.
5. Patients who were physically and mentally compe- The dosage was chosen based on our previous experience in shockwave application for other tendinopathies.3,13,26,28,31,33 6. Patients who were in good general health The point of maximal tenderness was elicited by palpation,and the location of the lesion was focused with the laser con- trol guide of the device. The depth of treatment was estimatedclinically and confirmed with an ultrasound guide. Surgical 1. Patients who received a cortisone injection within lubricant was applied to the skin in contact with the shock- wave tube. Treatment began with slow frequency at 1 impulse 2. Patients on immunosuppressant agents and/or cor- of shock per second and gradually increased to 2 shocks per second as the patient could tolerate the procedure.
2007 American Orthopaedic Society for Sports Medicine. All rights reserved. Not for commercial use or unauthorized distribution.
The American Journal of Sports Medicine Allocation
Follow-up
Analysis
Figure 1. The flow diagram showing patient selection. NSAID, nonsteroidal anti-inflammatory drug.
Immediately after treatment, the area was inspected for out with the administration of NSAIDs. A Cox-2 specific swelling, ecchymosis, and hematoma. Postoperative manage- inhibitor (celecoxib) was prescribed to patients who devel- ment included ice pack to the treatment site and a prescrip- oped allergic reaction or gastrointestinal toxicity to tion of nonnarcotic analgesic, such as acetaminophen.
NSAIDs. Patients were then treated with multiple modal- Patients were allowed to resume light activity; however, ities when they failed to respond adequately to treatment heavy activities including sports were not permitted for 4 with a single modality. Nearly all patients eventually received multiple modalities during the course of treat- Three patients (4 knees) also received a second treatment ment. None received local cortisone injection.
because of either inadequate response or recurrent symp-toms 4 to 6 weeks after the first treatment. Inadequate response was defined when the patient showed less than50% improvement and experienced pain at 5.0 or greater on The follow-up examinations were scheduled at 1, 3, 6, and a 0-to-10 visual analog scale (VAS) on stairs and palpation.
12 months and then once a year. Evaluations were carried The dosage of the second shockwave application was the out by telephone interview in 9 patients (10 knees), includ- ing 4 patients (4 knees) in the study group and 5 patients Patients in the control group were treated with conser- (6 knees) in the control group. The remaining evaluations vative treatments including NSAIDs, physiotherapy, an were performed in person by an independent examiner exercise program, the use of a knee strap, and modification blinded to the nature of the study protocol. The evaluation of activity levels. Physiotherapy modalities included hot parameters included pain score, Victorian Institute of Sport and cold packs, phonophoresis, and friction massage. The Assessment (VISA)4,12 score for symptoms and function of exercise program included a primarily eccentric stretching the knee, and ultrasonographic examination. The intensity of exercise of the patellar tendon and strengthening exercises pain was measured on a visual analog scale from 0 to 10, of the quadriceps and hamstrings. Most patients started with 0 for no pain and 10 for severe pain on palpation and on 2007 American Orthopaedic Society for Sports Medicine. All rights reserved. Not for commercial use or unauthorized distribution.
Extracorporeal Shockwave for Chronic Patellar Tendinopathy Patient Demographic Characteristicsa Pain Score, VISA Score, and Functional Improvement walking upstairs and downstairs, and the consumption of pain medication. The symptoms and function of the knee were graded with a 100-point VISA scale.4,12 The functional improvement of the knee was subjectively assessed by the patients and measured by the performance of activities of daily living, including sports. The result was considered sat- isfactory if patients had 75% or more improvement in pain with 4.0 or less on a VAS scale while walking up and down stairs and did not take any pain medication. The clinical out- comes were graded excellent, good, fair, or poor. An excellent result was defined as the knee having no pain in all activitiesincluding sports. A good result was defined as the knee hav- aVISA, Victorian Institute of Sports Assessment score; VAS, visual ing 75% or more improvement and mild pain with a VAS less analog scale from 0 to 10; P value (1), Comparison of data before and than 4 in all activities including sports. A fair result was after treatment of the same group; P value (2), Comparison of data defined as the knee having 50% or more improvement and between the study group and the control group.
moderate pain with a VAS less than 4 in any activities bThe percentage of functional improvement of the knee was including sports. A poor result was defined as the knee hav- based on the overall subjective assessment by comparing with the ing less than 50% improvement and significant pain with a VAS greater than 4 in any activities including sports.
Ultrasonographic examinations of the proximal patellar and power = 0.8, with calculation based on the outcomes of tendon were performed before and after treatment. High- extracorporeal shockwave and conservative treatment for resolution sonography was performed by using a Sequoia chronic patellar tendinopathy in this study. The data before 512 scanner (Acuson, Mountain View, Calif) with a linear and after treatment within the same group were compared 8L5 transducer with the setting at 8 MHz. Routine color statistically using a paired t test, the data between the study Doppler study was also performed to evaluate the vascu- and control groups were compared with the Mann-Whitney larity of the patellar tendon. A radiologist blinded to the test, and the overall results and the changes in the vascu- study protocol interpreted the results of ultrasonographic larity on ultrasonography between the 2 groups were com- study. Ultrasound studies were used to evaluate the pared with the χ2 test with statistical significance at P < .05.
dimension and thickness of the proximal patellar tendon;the presence of edema or swelling within the tendon; the appearance, arrangement, and homogeneity of tendonfibers; and the vascularity of the patellar tendon.
The results of the pain score, VISA score, range of kneemotion, and functional improvement are summarized in Table 2. Significant improvements in pain score, VISAscore, and knee motion after treatment were noted in the A power analysis revealed that a sample size of 23 would be study group (P < .001). However, the improvements in the required to establish the statistical significance with α = .05 control group were statistically not significant (P > .05).
2007 American Orthopaedic Society for Sports Medicine. All rights reserved. Not for commercial use or unauthorized distribution.
The American Journal of Sports Medicine Results of Ultrasonographic Examinationa aValues are % (n). Excellent, No pain in all activities of daily living including sports; good, >75% improvement and had mild pain with visual analog scale less than 4 in any activities including sports; fair, >50% improvement and had moderate pain with visual analog scale less than 4 in any activities including sports; poor, <50% improve- ment and had significant pain with visual analog scale greater than 4 in any activities including sports. P value was calculated based on The differences in pain score, VISA score, and knee motion aThe data of patellar tendon thickness were obtained from the between the 2 groups were statistically not significant (P > proximal end of the patellar tendon near the insertion to the infe- .05) before treatment. However, the differences became sta- rior pole of the patella. P value (1), comparison of data before and tistically significant after treatment, favoring the study after treatment within the same group; P value (2), comparison of group (P < .05). The subjective assessment for functional data between the study group and the control group.
improvement of the knee after treatment was 84.8% for thestudy group versus 56.7% for the control group (P < .001).
The overall clinical outcomes are summarized in Table 3.
showed an increase in 4 and no change in 20 before treat- The overall results were excellent in 43%, good in 47%, fair ment versus an increase in 5 and no change in 19 after in 10%, and poor in none for the study group, and excellent treatment (P = .712). The difference in the vascularity of the in 0%, good in 50%, fair in 25%, and poor in 25% for the patellar tendon between the 2 groups was statistically not control group (P < .001). Satisfactory results were observed significant before treatment (P = .546); however, the differ- in 90% of the study group versus 50% of the control group ence was statistically significant after treatment (P = .027).
(P < .001). Recurrent symptoms were noted in 13% (4 of 30) There was no significant difference in the appearance, of the study group and 50% (12 of 24) of the control group arrangement, and homogeneity of the tendon fibers between (P = .014). Three patients (4 knees) in the study group had a second shockwave treatment for either recurrent symp-toms or inadequate response from the first treatment, and the results were excellent in 1, good in 1, and fair in 2.
For athletic participation, 10 of 15 patients in the study One patient from the study group developed transient group were able to return to the same level of sports activ- numbness and hypoesthesia around the anteromedial ities including basketball in 5, jogging in 2, handball in 1, aspect of the knee that resolved spontaneously with ice weight lifting in 1, and wrestling in 1, and the other 5 pack and observation. There were no systemic or local patients were able to return at lower levels including bas- complications directly or indirectly related to the use of the ketball in 4 and handball in 1. For the control group, 14 of device. There was no device-related problem.
14 athletic patients were able to return to sports activitiesat lower levels and none at the same level of sports activi- The results of ultrasonographic examination of the Patellar tendinopathy is defined as a degenerative process of patellar tendon are summarized in Table 4. There was a the patellar tendon of unknown origin. Chronic patellar 6% decrease in the proximal patellar tendon thickness tendinopathy is an overuse syndrome manifested with pain after shockwave treatment versus a 10% increase in the and tenderness attributable to mucoid and chondroid degen- control group. However, the difference in the changes of eration, formation of plump tenocytes, increased fibroblastic patellar tendon thickness between the 2 groups was sta- and myofibroblastic cells, and absent inflammatory cells.11,12,19 tistically not significant after treatment (P = .219). In the Some studies reported that a chronic painful patellar tendon study group, the vascularity of the patellar tendon showed exhibits increased occurrence of sprouting nonvascular sen- an increase in 7 and was unchanged in 23 before treatment sory, substance P–positive nerve fibers, and decreased occur- versus an increase in 15 and no change in 15 after treat- rence of vascular sympathetic nerve fibers and suggested that ment (P = .032). In the control group, the vascularity the altered sensory-sympathetic innervation may play a role 2007 American Orthopaedic Society for Sports Medicine. All rights reserved. Not for commercial use or unauthorized distribution.
Extracorporeal Shockwave for Chronic Patellar Tendinopathy in the pathogenesis of tendinopathy.14 Conservative treat- gene-related peptide after shockwave application. Maier ments including modification of activity; stretching and et al15 showed that high-energy extracorporeal shockwave strengthening exercises for the quadriceps, hamstrings, and to the distal rabbit femur resulted in a reduced concentra- patellar tendon; physiotherapy with heat and cold compres- tion of substance P in the femoral periosteum 6 weeks after sions and transfriction massage; and the use of a patellar shockwave application. These studies indicated that shock- strap to reduce stress on the patellar tendon are recom- wave may selectively lead to dysfunction of peripheral mended as the initial treatments of choice for chronic patel- sensory unmyelinated nerve fibers without affecting large lar tendinopathy.1,5,6 The results of conservative treatment myelinated nerve fibers responsible for motor function.
were inconsistent, and pain and tenderness frequently Other studies in animal experiments demonstrated that recurred.1,5 Surgery is indicated for cases with failure to con- shockwave stimulated the ingrowth of neovascularization servative treatments.7,8 However, the results of surgical associated with increased expressions of angiogenic growth treatment are unpredictable and inconsistent.4,5,7,19 Some factors including endothelial nitric oxide synthase, vessel studies reported that sclerosing injections with polidocanol endothelial growth factor, and proliferating cell nuclear resulted in significant improvement in knee function and antigen.30,32 Neovascularization may play a role in the reduced pain in patients with patellar tendinopathy.10 The improvement of blood supply leading to tissue regeneration results of the current study showed that extracorporeal in tendinopathy. Chronic patellar tendinopathy manifested shockwave treatment produced superior results to tradi- as mucoid and chondroid degeneration of the tendon fibers, tional conservative treatments for patients with chronic increased fibroblastic and myofibroblastic cells, and altered patellar tendinitis. The recurrent rate was lower, and the sensory-sympathetic innervation.11,12,14,19 In this study, a significant increase in the vascularity of the patellar tendon Currently, Food and Drug Administration–approved was noted after shockwave treatment. It appeared that shockwave devices included Sanuwave OssaTron, Dornier shockwave treatment resulted in an increase in microscopic Epos, Siemens Sonocur, and Medscape Orthospec. High- and neovascularity in animal experiment as well as an increase low-energy shockwave devices are manufactured by differ- in macroscopic vascularity of the patellar tendon on ultra- ent sources of shockwave generators including electrohy- sonographic study. It is reasonable to believe that shock- draulic, electromagnetic, and piezoelectric. In clinical wave relieved pain by hyperstimulation analgesia, application, multiple treatments are required with low- improvement in blood supply, and promotion of tissue regen- energy devices, whereas single treatment is recommended eration in chronic patellar tendinopathy.
with high-energy machines. In this study, the high-energy There are limitations in this study. The number of patients OssaTron (High Medical Technology) orthotriptor was used, was small even though they met the power requirement. The and patients received a single session of treatment. The length of follow-up was relatively short. The functional majority of the published papers showed positive effects of improvement of the knee was assessed subjectively on the high-energy shockwave in various tendinopathies of the performance of daily activities including sports participation.
shoulder, elbow, knee, and heel.3,13,16,20,21,23-28,31,33 Only a few The grading method on the clinical outcome of excellent, studies reported less favorable results comparable with good, fair, and poor in this study is not validated. In addition, placebo effect.2,9 The discrepancy was attributed to bias in the method of patient randomization by medical record num- patient selection, the use of low-dose shockwave in the con- ber potentially compromised the concealment of patient trol group, the use of different low-energy devices, and a Many studies reported the cumulative effects of shock- wave in the treatment of tendinopathies of the shoulder,elbow, and heel.3,13,26,28,31,33 In this study, 3 patients (4 Extracorporeal shockwave treatment appeared to be more knees) also received a second treatment, and the results effective and safer than traditional conservative treatment were 1 excellent, 1 good, and 2 fair. It appeared that shock- in the management of patients with chronic patellar wave treatment showed a cumulative effect in chronic patellar tendinopathy similar to other tendinopathies.
Some authors reported that repetitive low-energy shock- wave application without local anesthesia is more effectivethan repetitive low-energy shockwave application with Funds were received in total or partial support for the local anesthesia in the treatment of chronic plantar fasci- research or clinical study presented in this article. The itis.22 In this study, no local or regional anesthesia was funding source was from Chang Gung Research Fund given, and all patients tolerated the procedure well with- (CMRP 8015) and National Health Research Institute (NHRI-EX95-9423EP). No benefits in any form have been The mechanism of shockwave remains unknown. Some received or will be received from a commercial party studies speculated that shockwave relieves pain caused by related directly or indirectly to the subject of this article.
tendinopathy through hyperstimulation analgesia by increas-ing the painful level of stimulation.17 Ohtori et al18 demon- REFERENCES
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