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  • Corticosteroid injections, eccentric decline squat training and heavyslow resistance training in patellar tendinopathy

    M. Kongsgaard1, V. Kovanen2, P. Aagaard1,3, S. Doessing1, P. Hansen1, A. H. Laursen1, N. C. Kaldau1, M. Kjaer1,

    S. P. Magnusson1

    1Institute of Sports Medicine, Department 8, Bispebjerg Hospital and Faculty of Health Sciences, University of Copenhagen,Copenhagen, Denmark, 2Department of Health Sciences, University of Jyvaskyla, Jyvaskyla, Finland, 3Institute of Sports Exerciseand Clinical Biomechanics, University of Southern Denmark, Odense, DenmarkCorresponding author: Mads Kongsgaard, PhD, MSc, Department 8, Institute of Sports Medicine, Bispebjerg Hospital andFaculty of Health Sciences, University of Copenhagen, 1st Floor, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark. Tel:145-3531 2599, Fax: 145-3531 2733, E-mail:

    Accepted for publication 24 February 2009

    A randomized-controlled single-blind trial was conducted toinvestigate the clinical, structural and functional effects ofperitendinous corticosteroid injections (CORT), eccentricdecline squat training (ECC) and heavy slow resistancetraining (HSR) in patellar tendinopathy. Thirty-nine malepatients were randomized to CORT, ECC or HSR for 12weeks. We assessed function and symptoms (VISA-p ques-tionnaire), tendon pain during activity (VAS), treatmentsatisfaction, tendon swelling, tendon vascularization, tendonmechanical properties and collagen crosslink properties.Assessments were made at 0 weeks, 12 weeks and atfollow-up (half-year). All groups improved in VISA-p andVAS from 0 to 12 weeks (Po0.05). VISA-p and VAS

    improvements were maintained at follow-up in ECC andHSR but deteriorated in CORT (Po0.05). In CORT andHSR, tendon swelling decreased ( 13 9% and 1213%, Po0.05) and so did vascularization ( 52 49% and 45 23%, Po0.01) at 12 weeks. Tendon mechanicalproperties were similar in healthy and injured tendons andwere unaffected by treatment. HSR yielded an elevated col-lagen network turnover. At the half-year follow-up, treatmentsatisfaction differed between groups, with HSR being mostsatisfied. Conclusively, CORT has good short-term but poorlong-term clinical effects, in patellar tendinopathy. HSR hasgood short- and long-term clinical effects accompanied bypathology improvement and increased collagen turnover.

    Patellar tendinopathy is a disabling overload injuryof the patellar tendon that may persist for 415 years(Kettunen et al., 2002). It has been reported thatjumping athletes and recreational athletes have aprevalence rate of 40% and 14%, respectively (Fer-retti, 1986; Lian et al., 2005). Tendinopathy has beenassociated with pathological extracellular matrix(ECM) changes (Cook et al., 1997), but specificstructural, functional and mechanical properties ofthe tensile-bearing component in tendinopathy re-main to be identified.Patellar tendinopathy lacks an obvious treatment

    of choice (Cook et al., 1997). Corticosteroid injec-tions are commonly used clinically, but recent histo-pathological data indicate that tendinopathy is anon-inflammatory condition (Cook et al., 1997; Al-fredson et al., 2001). Moreover, studies on tendinoustissue samples suggest that corticosteroids have de-leterious effects (Wong et al., 2004; Haraldsson et al.,2006). Yet, studies have reported reduced tendonpain, swelling and vascularization following corti-costeroid injections in patellar tendinopathy (Fred-berg, 1997; Fredberg et al., 2004). Thus, the effect of

    corticosteroid injections in patellar tendinopathyremains elusive.Conservative treatment for patellar tendinopathy

    in the form of eccentric training performed twicedaily has gained popularity, and some (Purdam et al.,2004; Jonsson & Alfredson, 2005), but not all (Visneset al., 2005), studies report a positive short-termclinical outcome. However, the explanatory mechan-isms of eccentric training in tendinopathy remainelusive, and the treatment has seldom been comparedwith that of other management therapies.The magnitude of load in exercise-based manage-

    ment of patellar tendinopathy appears to be funda-mental (Purdam et al., 2004; Kongsgaard et al., 2006;Frohm et al., 2007). Because heavy resistance train-ing can produce both tendon hypertrophy and aug-mented tendon mechanical properties (Kongsgaardet al., 2007), we hypothesized that heavy slow resis-tance training would be advantageous in the treat-ment of patellar tendinopathy.Existing clinical studies on tendon overload inju-

    ries have more or less exclusively focused on theclinical outcome, which precludes any explanation

    Scand J Med Sci Sports 2009: 19: 790802& 2009 John Wiley & Sons A/Sdoi: 10.1111/j.1600-0838.2009.00949.x


  • for the reported benefits, and therefore limits thepossibility of developing new and more effectivetreatment options.We investigated, in a single-blind randomized-

    controlled trial, the clinical, structural and functionaleffects of peritendinous corticosteroid injections(CORT), eccentric decline squat training (ECC)and heavy slow resistance training (HSR) in patellartendinopathy. The present study was conducted tocompare the three management options in additionto investigating some of the associated underlyingmechanisms of these managements.

    Materials and methodsPatients and design

    From January 2006 through June 2006, 52 recreational maleathletes (1850 years) diagnosed with chronic patellar tendi-nopathy applied for trial submission (self-selection followingadvertisement). An experienced physician confirmed the diag-nosis based on defined clinical findings. A pain duration of43months was required to qualify as a chronic condition(Leadbetter, 1992). The clinical diagnosis required confirmationby ultrasonography: local anteriorposterior (AP) thickening ofthe tendon of at least 1mm compared with the mid-tendonlevel, and a hypo-echoic area and presence of a color Dopplersignal within the hypo-echoic area (Cook et al., 2001). A4-week wash-out period from any previous treatment wasrequired. The exclusion criteria were as follows: (1) corticoster-oid injections within 12 months, (2) previous knee surgery, (3)arthritis, (4) diabetes or (5) any confounding diagnosis to theknee joint. Thirty-nine subjects fulfilled the inclusion criteriaand 13 subjects were randomly allocated to each group (Fig. 1).

    A prospective randomized single-blind clinical trial designwith a 12-week intervention period and a half-year follow-upperiod was applied and carried out at the Institute of SportsMedicine, Copenhagen. Following baseline assessments, sub-jects were allocated to one of the three intervention groups(CORT, ECC or HSR) using a computer-generated minimiza-tion randomization procedure (Jensen, 1991). The minimiza-

    tion randomization procedure was performed according toactivity level, symptom duration and age.

    Subjects with bilateral symptoms received the same treat-ment on both sides, but only the tendon with the greatestsymptoms was selected for analysis to preclude biased reduc-tion of the variance. Tendons without any clinical symptoms,sonographical hypoechoic abnormalities or detectable colorDoppler signal were used as a healthy tendon sub-sample forbaseline comparison (n5 26). Two subjects (one CORT and oneECC) withdrew from the study. One withdrew due to reasonsrelated to vacation and one withdrew due to an ankle sprain(week 2). The subject characteristics are shown in Table 1.

    The study complied with the Declaration of Helsinki, wasapproved by the local ethics committee for medical research (KF256131) and was registered at (NCT00404469).All subjects gave their written informed consent to participate.


    CORT subjects received ultrasound-guided (gray scale) injec-tions of 1mL of 40mg/mL methylprednisolon in 0.5mLlidocain (1%) into the peritendinous tissue posterior to thehypoechoic area of the patellar tendon. Injections were ad-ministered from the medial side of the knee. A second injectionwas administered 4 weeks later according to normal clinicalpractice. The same physician administered all the injections.Subjects were instructed to refrain from training and sportingactivities the first week after the injections.


    The eccentric exercise program has been described in detailpreviously (Purdam et al., 2004). Subjects performed three setsof 15 slow repetitions of eccentric unilateral squats on a 251decline board twice daily (morning and evening) for 12 con-secutive weeks (Fig. 2(a)). Subjects were instructed to spendapproximately 3 s completing each repetition and to have a 2-min rest period between sets. Subjects with a bilateral conditionused the arms and both legs during the concentric phase. Toensure compliance and correct performance of the exercises, asupervised training was conducted once a week. Pain duringexercises was acceptable, but pain and discomfort was not toincrease following cessation of training. Load was increasedusing an incrementally loaded backpack as pain diminished.


    Three weekly sessions, including one supervised session, wereperformed. Each session consisted of three bilateral exercises:squat, leg press and hack squat (Fig. 2(b)(d)). Subjectscompleted four sets in each exercises with a 23-min restbetween sets. The repetitions/loads were: 15 repetition max-imum (RM) week 1, 12RM weeks 23, 10RM weeks 45,8RM weeks 68 and 6RM weeks 912. All exercises wereperformed from complete extension to 901 of knee flexion andback again. Subjects were instructed to spend three secondscompleting each of the eccentric and concentric phases,respectively (i.e. 6 s/repetition). Pain during exercises wasacceptable but pain and discomfort was not to increasefollowing cessation of training.

    Subjects in all groups were allowed to perform sportingactivities througho