Comparing Rest Alone to Bandaging and Rest in Horses With Superficial Digital Flexor Tendinopathy

a Knowledge Summary by

Rafael Alzola BVMS, MSc, Cert AVP (EP, ESST, ESO, VDI) MRCVS ^1*

Sarah L. Freeman BVetMed, PhD, CertVA, CertVR, CertES, DipECVS, FHEA, FRCVS ²

¹Oakham Veterinary Hospital, Nottingham University, Ashwell Road, Oakham, Rutland, LE15 7QH
²School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Leicestershire, LE12 5RD
^*Corresponding Author (rafael.alzola@oakhamvethospital.co.uk)

Clinical scenario

The evidence

There is no evidence within the literature to support that any type of bandaging enhances tendon healing during the resting period following a tendon injury. However, bandaging (cast bandage) has a significant effect limiting lesion propagation during the initial inflammatory phase in SDF tendinopathies. The quality of the evidence comparing rigid versus nonrigid bandages to limit lesion propagation is of moderate quality and reliability. In different randomised controlled trials lesion propagation was significantly reduced using a short period (10 days) of cast immobilisation compared to a two layer Robert Jones bandage or no bandage. However, the studies only included either surgically or collagenase-induced lesions and need validating in naturally occurring injuries. Potential short or long-term detrimental effects of immobilisation (cast) were not investigated in these studies.

Summary of the evidence

Appraisal, application and reflection

This PICO question focuses on the benefits of bandaging and rest versus rest alone for treating superficial digital tendonitis in equids. The four relevant studies found to fit the PICO criteria were prospective experimental studies and the evidence gained from them is reported above. This represents evidence of moderate quality and reliability as only one of the two in vivo studies, contrary to the in vitro, mimic the naturally occurring injuries.

Superficial digital flexor (SDF) tendinopathy is a common injury in equine athletes, following undefined periods of accumulation of exercise and age related microdamage without any preceding clinical signs. Complete tendon healing is a long process, re-injury rates are high, and these injuries are potentially career ending for the most severe cases. Lesion size is directly linked to prognosis, with poorer prognosis for larger SDFT injuries (Alzola et al., 2018). Therefore, tendinopathy is a significant health and welfare concern in horses.

In clinical situations, SDF tendinopathies have a tendency to propagate (length and width) significantly during the first few weeks after initial injury due to the combination of enzymatic and biomechanical stimulation (Bosch et al., 2010). The tendon healing process follows the general pattern of wound healing with overlapping phases: inflammatory, proliferative and maturation phase. Lesion propagation occurs during the initial inflammatory phase (approx. 10–21 days) when the disrupted tendon fibres are digested by proteolytic enzymes like metalloproteinases and then removed by phagocytosis ( Leadbetter, 1992 and Palmer et al., 1994). Biomechanical loading, even at very low levels, induces propagation but only in conjunction with the activity of proteolytic enzymes (Bosch et al., 2010). Therefore, results from ex vivo cadaveric studies should be interpreted with caution as inflammation cannot be reproduced.

There is no evidence within the literature to support that any type of bandaging promotes tendon healing during the resting period. However, bandaging has a significant effect on limiting lesion propagation. Ex vivo (Bosch et al., 2010) and in vivo (David et al., 2012) studies have proven that motion restriction of the lower limb with a rigid bandage (cast bandage) significantly reduces lesion propagation during the acute phase improving prognosis. Nonsteroidal anti-inflammatory drugs (NSAIDs) also influence lesion propagation by inhibiting inflammation and concomitantly proteolytic enzyme activity (Mehallo et al., 2006), but review of this evidence is beyond the scope of this knowledge summary.

Flexor tendons (SDFT and DDFT) and the suspensory ligament remain loaded for as long as the limb is weight-bearing, even in box rested horses. Biomechanical loading on the SDFT is maximal during hyperextension of the metacarpophalangeal (MCP) joint. In the standing horse, resistance to extension of the MCP joint is a passive process; an increase in MCP joint angle will result in an increase strain in the tendons and ligaments (Bartel et al., 1978 and Shoemaker et al., 1991).

Multiple external support techniques (rigid/nonrigid) have been used to resist overextension of the MCP joint to reduce potentially damaging peak loads and strains to the SDFT after injury or to reduce re-injury risk. Contrary to rigid bandages, in an ex vivo study, nonrigid support systems (conventional bandages) did not provide significant resistance to MCP joint extension during the stance phase or walk (Smith et al., 2002). Reducing MCP joint extension is essential in the box rest period for tendon healing. Controversially in an in vivo study, support boots did reduce significantly MCP joint extension during walk and trot (Kicker et al., 2004). Using ultrasonography in an ex vivo equine model of acute SDFT injury (collagenase-induced model), lesion length was significantly greater (P<0.05) in the repetitively loaded forelimbs compared to the cast (half forelimb cast) or unloaded forelimbs that were almost identical (Bosch et al., 2010). In this study, there was no difference in lesion width or in the force at rupture (F failure) between uncast and cast limbs. In a more recent in vivo study using computerised ultrasonographic tissue characterisation to evaluate surgically induced SDFT lesions, limb casting reduced significantly lesion size (length and width) compared to bandaging with a 2-layer Robert Jones bandage (P≤0.04). These findings were also corroborated during macroscopic evaluation of the lesions. In this study, cast immobilisation for ten days during the early phase of tendon healing effectively reduced lesion propagation compared to bandaging (David et al., 2012). Although there is no evidence in equids regarding the optimal immobilisation time during the rest period, ten day cast immobilisation is in accordance with the human literature that recommends casting only during the acute phase of tendon injuries for about 5–7 days (Buckwalter, 1995).

Cast immobilisation during the acute inflammatory phase provides constant counter-pressure to longitudinal, transverse and rotational forces and avoids MCP hyperextension (Smith et al., 2002) avoiding lengthening of injured structures and slowing down the “pump” phenomenon at the tendon level (Cribb & Scott, 1995), hence preventing lesion propagation. In addition, cast immobilisation will also limit secondary SDFT injuries (Kannus et al., 2003).

Some human studies have shown that stress deprivation of the SDF tendon induced by long-term cast immobilisation could negatively affect tendon biochemical and biomechanic properties, as well as tendon repair (Yasuda & Hayashi, 1999 and Aspenberg, 2007). However, the former effects are time dependent and, therefore, reversible with remobilisation. Short term immobilisation does not result in significant reduction of physiological properties in healthy tendons (Christensen et al., 2008). Likewise, half limb casting does not seem to produce a complete stress shielding effect in equids, providing some degree of mechanical stimulation (David et al., 2012), which is known to avoid tendon degeneration (Nabeshima et al., 1996).

An early and gradual increase in physical load improves healing by enhancing synthesis of collagen during the proliferation phase and alignment of collagen fibres in the remodelling phase (Dowling et al., 2000 and Aspenberg, 2007). After cast removal, the support provided to the MCP joint should be reduced gradually using less rigid support systems: modified Robert Jones distal limb bandage with a contoured palmar splint, Dalmar tendon support boot (Smith et al., 2010) or some support boots (Eskadron or TSM AED Reha- and Sportsbandages) (Kicker et al., 2004). This will avoid sudden increase in tissue loading throughout healing tissues. Unfortunately, not all of these systems will be practical to use in exercising horses during rehabilitation. Lesion length and lesion width is bound to increase after support removal in both cast and bandage, although these changes were significantly shorter and smaller in casted lesions (David et al., 2012). After cast removal, rest should be continued until the initial inflammatory response subsides (approx. 4–6 weeks in total) and followed by a well designed exercise programme to achieve optimal alignment of collagen fibres (Kicker et al., 2004).

In conclusion, bandaging does not enhance tendon healing during the rest period (acute inflammatory phase) but a short period (ten days) of cast immobilisation improves prognosis for SDF tendinopathies by preventing lesion propagation with minimal negative effects to the tendon. Cast immobilisation period must be followed by early functional therapy to enhance tendon healing using support systems to reduce extension MCP joint and subsequently tension in the SDFT.

Methodology Section

Search Strategy
Databases searched and dates covered:	CAB Abstracts on OVID Platform (1973–2018 Week 35) PubMed via the NCBI website (1910–September 2018)
Search terms:	CAB Abstracts: (equine or equines or horse or horses or equus or equid or equids or mare or mares or broodmare or broodmares or pony or ponies or filly or fillies or colt or colts or yearling or yearlings or stallion or stallions or thoroughbred or thoroughbreds or Standardbred or Standardbreds or racehorse or racehorses or race horse or race horses).mp. or exp horses/ or exp equus/ or exp equidae/ or exp mares/ or exp colts/ or exp foals/ or exp stallions/ or exp thoroughbred/ or exp racehorses/. ("superficial digital flexor tendon" or "superficial digital flexor tendons" or "digital flexor tendon" or "digital flexor tendons" or "superficial digital flexor tendonitis" or "superficial digital flexor tendinitis" or "superficial digital flexor tendinopathy" or SDFT or "superficial digital tendon" or "superficial digital tendonitis" or "superficial digital tendinitis" or "superficial digital tendinopathy" or SDF or tendonitis or tendinitis). (bandages or bandaging or bandaged or bandage or binding or bind or bound or binds or dresses or dressing or dressed or dressings or cast or casting).mp. or exp bandages/. (rest or resting or rested or rests). 1 and 2 and (3 or 4). PubMed  equine OR equines OR horse OR horses OR equus OR equid OR equids OR mare OR mares OR broodmare OR broodmares OR pony OR ponies OR filly OR fillies OR colt OR colts OR yearling OR yearlings OR stallion OR stallions OR thoroughbred OR thoroughbreds OR Standardbred OR Standardbreds OR racehorse OR racehorses OR race horse OR race horses. ‘superficial digital flexor tendon’ OR ‘superficial digital flexor tendons’ OR ‘digital flexor tendon’ OR ‘digital flexor tendons’ OR ‘superficial digital flexor tendonitis’ OR ‘superficial digital flexor tendinitis’ OR ‘superficial digital flexor tendinopathy’ OR SDFT OR ‘superficial digital tendon’ OR ‘superficial digital tendonitis’ OR ‘superficial digital tendinitis’ OR ‘superficial digital tendinopathy’ OR SDF OR tendonitis OR tendinitis bandages OR bandaging OR bandaged OR bandage OR binding OR bind OR bound OR binds OR dresses OR dressing OR dressed OR dressings OR cast OR casting. rest OR resting OR rested OR rests. 1 AND 2 AND (3 OR 4)
Dates searches performed:	11th September 2018

Exclusion / Inclusion Criteria
Exclusion:	Non English or Spanish language publications or articles not relevant to the PICO. No study was excluded based on the study type.
Inclusion:	Studies available in English or Spanish relevant to the PICO

Search Outcome
Database	Number of results	Excluded – Not in English or Spanish lan-guage	Excluded – did not address the PICO question	Excluded – duplication	Total relevant papers
CAB Abstracts	77	16	58	0	3
PubMed	32	1	28	2	1
Total relevant papers when duplicates removed					4

The authors extend their thanks to Myai Du for doing the abstract search to answer this PICO question.

1. Alzola, R., Riggs, C.M., Gardner, D.S., and Freeman, S.L. (2017). “Ultrasonographic scoring system for superficial digital flexor tendon injuries in horses: Intra- and inter- rater variability”. Vet Rec 181(24): 1– DOI: http://dx.doi.org/10.1136/vr.104233
2. Alzola, R., Easter, C., Riggs, C.M., Gardner, D.S., and Freeman, S.L. (2018). "Ultrasonographic-based predictive factors influencing successful return to racing after superficial digital flexor tendon injuries in flat racehorses: A retrospective cohort study in 469 Thoroughbred racehorses in Hong Kong." Equine Vet J 50(5): 602– DOI: 10.1111/evj.12810
3. Aspenberg, P. (2007). "Stimulation of tendon repair: mechanical loading, GDFs and platelets. A mini-review." Int Orthop 31(6): 783– DOI: 10.1007/s00264-007-0398-6
4. Bartel, D.L., Schryver, H.F., Lowe, J.E., and Parker, R.A. (1978). "Locomotion in the horse: a procedure for computing the internal forces in the digit." Am J Vet Res 39(11): 1721–
5. Bosch, G., Lameris, M.C., van den Belt, A.J., Barneveld, A., and van Weeren, P.R. (2010). "The propagation of induced tendon lesions in the equine superficial digital flexor tendon: an ex vivo study." Equine Vet J 42(5): 407– DOI: 10.1111/j.2042-3306.2010.00099.x
6. Buckwalter, J.A. (1995). "Should bone, soft-tissue, and joint injuries be treated with rest or activity?" J Orthop Res 13(2): 155– DOI: 10.1002/jor.1100130202
7. Christensen, B., Dyrberg, E., Aagaard, P., Kjaer, M., and Langberg, H. (2008). "Short-term immobilization and recovery affect skeletal muscle but not collagen tissue turnover in humans." J Appl Physiol (1985) 105(6): 1845– DOI: 10.1152/japplphysiol.90445.2008
8. Cribb, A.M. and Scott, J.E. (1995). "Tendon response to tensile stress: an ultrastructural investigation of collagen:proteoglycan interactions in stressed tendon." J Anat 187(Pt 2): 423–
9. David, F., Cadby, J., Bosch, G., Brama, P., van Weeren, R., and van Schie, H. (2012). "Short-term cast immobilisation is effective in reducing lesion propagation in a surgical model of equine superficial digital flexor tendon injury." Equine Vet J 44(5): 570– DOI: 10.1111/j.2042-3306.2011.00513.x
10. Dowling, B.A., Dart, A.J., Hodgson, D.R., and Smith, R.K., (2000). "Superficial digital flexor tendonitis in the horse." Equine Vet J 32(5): 369– DOI: https://doi.org/10.2746/042516400777591138
11. Kannus, P., Parkkari, J., Jarvinen, T.L., Jarvinen, T.A., and Jarvinen, M. (2003). "Basic science and clinical studies coincide: active treatment approach is needed after a sports injury." Scand J Med Sci Sports 13(3): 150– DOI: https://doi.org/10.1034/j.1600-0838.2003.02225.x
12. Kicker, C.J., Peham, C., Girtler, D., and Licka, T. (2004). "Influence of support boots on fetlock joint angle of the forelimb of the horse at walk and trot." Equine Vet J 36(8): 769– DOI: https://doi.org/10.2746/0425164044848208
13. Leadbetter, W.B. (1992). "Cell-matrix response in tendon injury." Clin Sports Med 11(3): 533–
14. Mehallo, C.J., Drezner, J.A., and Bytomski, J.R. (2006). "Practical management: nonsteroidal antiinflammatory drug (NSAID) use in athletic injuries." Clin J Sport Med 16(2): 170– DOI: 10.1097/00042752-200603000-00015
15. Nabeshima, Y., Grood, E.S., Sakurai, A., and Herman, J.H. (1996). "Uniaxial tension inhibits tendon collagen degradation by collagenase in vitro." J Orthop Res 14(1): 123– DOI: https://doi.org/10.1002/jor.1100140120
16. Palmer, S.E., Genovese, R., Longo, K.L., Goodman, N., and Dyson, S. (1994). "Practical management of superficial digital flexor tendinitis in the performance horse." Vet Clin North Am Equine Pract 10(2): 425– DOI: https://doi.org/10.1016/S0749-0739(17)30363-2
17. Shoemaker, R.S., Bertone, A.L., Mohammad, L.N., and Arms, S.W. (1991). "Desmotomy of the accessory ligament of the superficial digital flexor muscle in equine cadaver limbs." Vet Surg 20(4): 245– DOI: https://doi.org/10.1111/j.1532-950X.1991.tb01254.x
18. Smith, R.K., McGuigan, M.P., Hyde, J.T., Daly, A.S., Pardoe, C.H., Lock, A.N., and Wilson, A.M. (2002). "In vitro evaluation of nonrigid support systems for the equine metacarpophalangeal joint." Equine Vet J 34(7): 726– DOI: https://doi.org/10.2746/042516402776250423
19. Yasuda, K. and Hayashi, K. (1999). "Changes in biomechanical properties of tendons and ligaments from joint disuse." Osteoarthritis Cartilage 7(1): 122– DOI: 10.1053/joca.1998.0167

RCVS Knowledge was supported in producing this Knowledge Summary by an educational grant from Petplan Charitable Trust.