FREE ELECTRONIC LIBRARY - Theses, dissertations, documentation

Pages:   || 2 |

«Delayed Patellar Release (Also described as: intermittent upward fixation of the patella (IUFP), upward fixation of the patella (UFP), ‘stifled,’ ...»

-- [ Page 1 ] --

Your Horse's Health

Veterinary Medicine with

Matt Durham, DVM

Published in Bay Area Equestrian Network September 2007

Delayed Patellar Release

(Also described as: intermittent upward fixation of the patella (IUFP), upward fixation of the patella (UFP),

‘stifled,’ catching stifles, locked stifles, sticky kneecaps…)

Horses, as we all know, have many special abilities. Among the less dramatic,

but no less important, of these abilities is their ability to sleep standing up. Horses have a complex system called the passive stay apparatus that allows them to do this while using minimal muscular effort. One of the keys to this system is the ability to lock the kneecap (patella) in place, which keeps the stifle extended. Normally, the horse can lock and unlock the patella with no resistance. Horses affected with delayed patellar release (DLP) have an alteration to their hind limb movement that can affect performance.

Anatomy Without the passive stay apparatus, the quadriceps muscle would be in constant use. Figure 1 shows the alignment of a normal stifle, which is analogous to the human knee. Imagine standing with your knees bent at this angle and trying to relax, or even rest one leg the way a horse does. We would fatigue very quickly in this position.

Humans minimize muscular effort at rest by bringing our knees back so that the thigh and shin are in a straight line. This takes minimal muscular effort to maintain, and allows the downward forces to travel straight through the bony column.

Horses have three ligaments connecting the patella to the tibia (shin bone), while humans and most other species have one ligament right in front. The end of the femur (thigh bone) in horses and in Figure 1 humans has a smooth, cartilage covered, pulley-shaped structure at the Skeletal anatomy showing femur lower end where the patella glides. This structure is called the (red arrow), trochlea (which means ‘pulley’ in Latin). In horses, the groove and patella (black the ridges are fairly pronounced (Figure 2) when compared with other arrow), and Tibia species, which is part of the reason why patellar luxation (where the (blue arrow).

patella slips out of the trochlear groove to the side) is not common in horses except the miniature horse. The top of the medial trochlear ridge in the horse is very pronounced, giving the patella a place to latch on.

The medial patellar

–  –  –

The Chicken or the Egg Horses with delayed patellar release often have lameness originating from the hind limb. Delayed patellar release itself can lead to lameness in the stifle: the increased friction of the patella against the trochlea of the femur can cause joint inflammation, and the patellar ligaments are sometimes strained. The joint inflammation can be treated, but unless the delayed patellar release is resolved, the lameness component will continue to resurface as a problem.

It is also common to have a lameness problem somewhere else in the limb, such as the hocks, which can be a contributing factor in the development of delayed patellar release.

Because there can be a mixture of factors occurring at the same time, it can sometimes be difficult to determine which is the ‘chicken’ and which is the ‘egg.’ In these cases, treatment directed at several areas may be necessary to resolve the issues.

Causes Upright conformation (Figure 5) through the stifle is an important risk factor. This causes the patella to sit higher above the trochlea, and for the prominent medial trochlear ridge to be directed somewhat more forward instead of mainly upward.

Overlong patellar ligaments have also been blamed, with the possibility of strain and repeated stretching as a potential risk factor.

Decreased muscle tone in the quadriceps muscles is known to be a factor. The other muscle that is important for patellar function is the biceps femoris, which helps to pull the patella to the side, releasing it from the trochlea.

Lack of fitness is often blamed as the cause. While unfit horses are definitely at risk, it is also not uncommon to see very fit horses affected. However, these fit horses often have what could be Figure 5 considered a hidden fitness issue: decreased or altered range of motion Upright stifle in the hind limb. Horses with an altered range of motion probably do conformation not develop normal coordinated movement in the quadriceps and biceps femoris muscles.

Contributing Factors

• Lack of fitness- This includes rapidly growing horses that have not developed the muscling and coordination to fit their bodies yet. Retired and other sedentary horses comprise another group at risk. Horses in lay-up for an injury will sometimes develop delayed patellar release as they are starting back into work. The common thread is decreased muscle tone.

• Concurrent lameness- Horses with lameness issues, particularly originating in the hind end and/or back, may develop delayed patellar release. Horses with sore hocks, for example, often have an altered range of motion, sparing their hind ends. This limited effort from the hind end probably causes deconditioning in the quadriceps and biceps femoris muscles.

• Neurologic disease- Wobblers and horses with other causes of neurologic disease can be affected. Neurologic disease can contribute directly and indirectly to delayed patellar release. If the nerve supply to the quadriceps or biceps femoris is affected, there is a direct effect on patellar release. Neurologic horses often lose overall muscle tone and coordination as well.

• Training factors- Fatigue is thought to contribute to delayed patellar release, particularly in young horses. Horses that use the hind end heavily, such as in cutting and dressage, particularly if in heavy training, may become fatigued. Fatigue may lead to uncoordinated movement. These are the classic horses that do not fall into the ‘unfit’ category. Some believe that these horses may be affected because of stretching of the patellar ligaments.

Horses with jobs that limit motion may also be affected. Western pleasure horses are often trained without doing any significant extended trot. This limited range of motion can contribute to delayed patellar release.

Keeping the horse in an ‘inverted’ or ‘hollowed out’ position during exercise are also thought to lead to poor patellar function.

• Mechanical factors- Hind foot balance is an often-overlooked factor. Horses with a long toe/ low heel conformation in the hind feet have an altered footflight: stride length does not tend to be affected, but the forward part of the stride is exaggerated and the back part of the stride is limited. These horses tend to overreach or forge, and tend to stumble. This alteration of range of motion probably changes the development in the quadriceps and biceps femoris muscles.

Horses with this conformation often have a bullnosed appearance to the foot.

When viewing the horse from the side, imagine a line following the coronary band of the hind foot up to the front leg of the horse. This line should hit around the chestnut of the front limb. In affected horses, this line will hit closer to the elbow or even back to the girth area. Some horses, when standing squarely on hard footing may be seen to have their heels slightly off of the ground. Some horses appear to have normal foot conformation when viewed from the side. X-rays of the hind foot (figure 6) can define the angulation of the coffin bone most precisely, and can be used to measure sole depth. Often, this can be corrected through trimming alone. At times, if sole depth at the toe is minimal, wedges can be used.

• OCD- Osteochondrosis in the stifle can affect the gliding surface of the patella.

Osteochondrosis dissecans (OCD) is a condition where the cartilage and underlying Figure 6. X-ray image of the hind foot in a bone on the surface of certain joints horse with delayed patellar release, showing very low heels, a bullnosed appearance to the develops abnormally. The trochlear ridges front of the foot, lack of contact in the heels, of the femur and sometimes the patella itself and negative P3 angle.

can be affected in the stifle.

Diagnosis In severely affected horses, diagnosis is obvious: the hind leg gets completely stuck in extension. Far more commonly, the patella is not completely locked, but hesitates in release, causing a gait abnormality that varies from barely perceptible to relatively obvious. While observing the horse at rest, rocking the hind end from side to side causes the stifle to engage and disengage. Affected horses have a snapping movement to the patella that can be seen, felt, and occasionally even heard as a ‘clunk’ as it snaps back into place.

While watching the horse in movement, affected horses tend to have a mechanical movement in the hind end at the walk. Some will drag the hind toes. Some affected horses move well at the trot, although there is sometimes an exaggerated snapping movement that can be seen along the Achilles’ tendon at the attachment to the hock.

Some affected horses may prefer the trot to the canter. The canter may be affected in one or both leads, and may appear awkward or mechanical. Canter-trot and canter-walk transitions are often very awkward in affected horses.

Because delayed patellar release is primarily a mechanical issue, nerve blocks and joint blocks typically do not change the patellar function. However, lameness is often present, so it is important to determine the source(s) of lameness, whether the lameness is a cause or a result of delayed patellar release.

X-rays of the stifle are helpful to rule out OCD and other bony abnormalities in the stifle. Radiographs of the hind feet are also useful to measure angles if low heels are a potential contributing factor.

Ultrasound can be useful in evaluating the patellar ligaments and other soft tissue structures of the stifle, including subtle OCD lesions not visible on x-rays.


• Conditioning- In some horses, resolution of delayed patellar release can be as simple as improving fitness level. This is often effective in horses that are obviously out of shape. Conditioning exercises are important for all affected horses, but exercise alone may be inadequate to resolve the issue in many horses. Helpful exercises include extended trot, trotting up hills, trotting over poles, and (with the right horse and a Western saddle) dragging objects such as hay bales or railroad ties.

• Resolution of underlying issues- When possible, underlying lameness issues should be resolved. Similarly, horses with neurologic disease will typically improve if the neurologic disease is treatable. Horses with low heel angles should have their balance corrected.

• Hormone injections- A series of injections of estrone sulfate (similar to estrogen) can be used to treat the condition. Estrogen causes relaxation of ligaments. One theory is that these injections relax some of the pelvic ligaments, altering the angulation of the pelvis and stifle. Another theory is that the patellar ligaments themselves relax. In some horses, this can be a very effective treatment.

Disadvantages include the need for repeated injections and hormonal behavioral changes, particularly in mares.

• Internal blistering- Injections of Iodine in oil in the medial patellar ligament or the medial and middle patellar ligaments can be an effective treatment.

• Medial patellar ligament transection- In this procedure, the medial patellar ligament is cut all the way through. This procedure has fallen from favor with most veterinarians because of the potential for development of arthritis in the joint and/or fragmentation in the patella due to rotation of the patella relative to the trochlea. This is the treatment of last resort for most veterinarians, reserved for those rare severely affected horses that become completely locked and do not resolve with other treatments.

• Medial patellar ligament splitting- In this newer procedure, instead of cutting through the ligament, multiple very small incisions are made into the ligament parallel to the fibers. This procedure is considered much safer for the joint than complete transection. This procedure was initially only done under general anesthesia, but some veterinarians prefer to perform the procedure with the horse standing under sedation.

• Joint therapy- Because many horses develop inflammatory joint disease from the increased friction in the joint, treatment for joint disease can be helpful. As with other joint issues, there are many levels of treatment. Because the inflammation is often not arising from the cartilage, but with the tissue that produces the joint fluid, IV hyaluronic acid (Legend®) can be effective, particularly in mildly affected horses.

Joint fluid in an inflamed joint becomes watery, and is a less effective lubricant.

Horses with lameness originating from the stifle may benefit from injections into the joint itself. The use of nutraceuticals may also be of some benefit.

One clinic’s approach to treatment At our clinic, the typical approach to treatment for a horse with delayed patellar release is to define as many risk factors as possible, including underlying lameness, neurologic, or shoeing issues, and attempt to remedy these. Depending on the severity, some horses may do well with conditioning exercises once the underlying issues are resolved. Horses affected more significantly will be started on intravenous Legend® and sometimes intramuscular Adequan®. Horses with stifle lameness may also receive stifle injections. We have moved away from hormone therapy and iodine injections, in favor of the patellar ligament splitting procedure, which we feel is very safe and very effective.

We prefer to perform the procedure with the horse standing. Arthroscopic surgery is typically recommended for horses with OCD lesions.

Conclusion Although delayed patellar release is a relatively common cause of decreased performance in horses, most cases can be treated effectively, allowing horses to return to full performance.

Image sources: Figures 1, 2 (left), 3, & 4: Sisson and Grossman’s Anatomy of the Domestic Animals.

Figure 2 (right: Michigan State University School of Veterinary Medicine. Figures 5 & 6: Steinbeck Country Equine Clinic.

Pages:   || 2 |

Similar works:

«Resource Guide for Internationally Educated Nurses Resource Guide for Internationally Educated Nurses The development of this Resource Guide is an initiative of the Provincial Chief Nurse, Department of Health and Community Services Production of this document has been made possible through a financial contribution from The views expressed herein do not necessarily represent the views of Health Canada. Developed by: Louanne Kinsella Produced by: Professional Development and Conferencing...»

«Association Liability Insurance Policy Association Liability Insurance Policy Notices 1 Preamble 3 1. Insuring clauses 3 Insuring clause 1: Civil liability professional indemnity insurance 3 Insuring clause 2: Office bearer’s liability 3 Insuring clause 3: Association reimbursement 3 Insuring clause 4: Association liability 3 Insuring clause 5: Employment practice liability 3 Insuring clause 6: Fidelity 3 Insuring clause 7: Tax audit 3 Insuring clause 8: Legal consultation 4 2. Extensions 4...»


«FROM THE 15th NOVEMBER LIFEQUOTE WILL MAKE ARRANGING LIFE INSURANCE EASIER THAN IT HAS EVER BEEN BEFORE BRIEFING PACK Attached: • Press Release • Background to the development of Express Underwriting • Sample sensitive ‘point of sale’ medical questions required by insurers online systems • What the ‘experts’ say about Express Underwriting • What customers say about their Express Underwriting experience • Sample Express Underwriting proposal • Sample standard proposal •...»

«Louisiana College Athletic Training Educational Program Policy and Procedure Manual PREFACE The following list of policies and procedures have been designed for the Louisiana College Athletic Training Educational Program. This manual is intended to set the guidelines and framework for which this athletic training student program stands on. With its detailed policies and procedures, it will act as a guide to assist our athletic training students in becoming certified athletic trainers. The...»

«1 11 April 2016 2 EMA/CHMP/QWP/834816/2015 3 Committee for Medicinal Products for Human Use (CHMP) Guideline on the requirements to the chemical and pharmaceutical quality documentation concerning investigational medicinal products in clinical trials Draft Draft agreed by Quality Working Party December 2015 December 2015 Adopted by CHMP for release for consultation February 2016 Consultation of European Commission ad hoc group on clinical trials 12 April 2016 Start of public consultation 12...»

«Help Wanted? Providing and Paying for Long-Term Care © OECD 2011 Chapter 9 Where To? Providing Fair Protection Against Long-term Care Costs and Financial Sustainability For most individuals, it is difficult to foresee whether long-term care (LTC) will be required in the future, and if so, the type, the duration and the cost of that care. Over the next decades, public expenditure in most OECD countries is expected to grow rapidly, in most part because of the expected increase in age-related...»

«American Recovery and Reinvestment Act Homelessness Prevention and Homelessness Prevention & Rapid Re-housing: Community Perspectives Homelessness Prevention Beth Stokes, Hamilton Family Center Rapid Re-Housing Tanya Tull & Ryan Macy-Hurley, Beyond Shelter Homelessness Prevention Beth Stokes, Executive Director Hamilton Family Center First Avenues: Housing Solutions for Families Homeless Prevention: Problem Statement Too often, evicted families enter shelter system. More cost „ effective to...»

«Alcorn State University Student Athletic Trainer Policy and Procedure Handbook 2015-2016 INTRODUCTION Athletic training is a part of the Sports Medicine profession that may require many hours of total dedication, hard work, self-discipline, and work. The NATABOC certified athletic trainer, ATC, is a highly educated, trained and skilled professional whose specialty is in athletic heath care. The ATC is recognized as an Allied Health Professional. As a sports medicine expert and member of the...»

«March 2015 ANNOTATED BIBLIOGRAPHY ON HEALTH POLICY IMPLEMENTATION AND EVALUATION This publication was prepared by Laili Irani, Karen Hardee, Stephanie Welsh, Mariela Rodriguez, and Matthew Hamilton of the Health Policy Project. H E A LT H POLICY PROJECT Suggested citation: Irani, L., K. Hardee, S. W elsh, M. Rodríguez, and M. Hamilton. 2015. Annotated Bibliography on Health Policy Im plem entation and Evaluation. W ashington, DC: Futures Group, Health Policy Project. ISBN: 978-1-59560-078-3...»

«DIRECTORS’ MEETING MONDAY, MAY 2, 2011 CITY-COUNTY BUILDING, ROOM 113 2:00 P.M. I. CITY CLERK II. MAYOR 1. NEWS RELEASE. Recycling office to sponsor “Shredding Day” Saturday.2. NEWS RELEASE. Task Force to train in Kansas this weekend.3. NEWS RELEASE. Public invited to celebrate Arbor Day.4. NEWS RELEASE. Mayor selects Assistant Fire Chief John Huff as Interim Fire Chief. 5. NEWS RELEASE. Lincoln is Tree City USA for 34th year. 6. Memo from Rick Hoppe, Chief of Staff, on City Council...»

«Candlelight Group: a pilot project for people with dementia Patricia Higgins RMN, Rev. Richard Allen, Dr. Samina Karamat, Dr. Robert Lawrence Introduction Religion is important to older people 1,2 and most individuals over 70 years of age who were born in the United Kingdom are from a generation for whom attending church and going to Sunday school was an integral part of everyday life. Those who have been active members of their parish and regular churchgoers may no longer be able to...»

<<  HOME   |    CONTACTS
2016 www.theses.xlibx.info - Theses, dissertations, documentation

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.