veterinarians continue cruciate unproven new knee surgery

[guest]

TIBIAL PLATEAU LEVELING PROCEDURE

Loïc M. Déjardin, DVM, MS, Diplomate ACVS, Michigan State University, East Lansing, Michigan
ACVS Symposium Equine and Small Animal Proceedings
October 1, 2002


<snip>

Loïc M. Déjardin, DVM, MS, Diplomate ACVS, Michigan State University, East Lansing, Michigan

TIBIAL PLATEAU LEVELING PROCEDURE

Loïc M. Déjardin, DVM, MS, Diplomate ACVS, Michigan State University, East Lansing, Michigan

2002 ACVS Veterinary Symposium Equine and Small Animal Proceedings

Small Animal Seminar

Orthopedic New Procedures – New Concepts Track

Keywords: Cruciate ligament failure, tibial ostetomies, biomechanics, orthopedic

Over the last 50 years, extra- and intra-articular techniques have been devised to restore joint stability secondary to CrCL rupture. Regardless of the technique, 85 to 90% of good to excellent results have been reported, despite the inability of either type of procedure to consistently maintain long term stifle stability, stop arthritis progression and prevent secondary meniscal tears. In an attempt to circumvent these limitations, a new approach to CrCL rupture has been introduced with the tibial plateau leveling osteotomy (TPLO) procedure. Unlike previous approaches, TPLO does not attempt to stabilize the joint throughout its range of motion (ROM), but rather provides functional stability during weight bearing by reducing the cranial tibial thrust (CrTT).

Effects of Tibial Plateau Leveling on Stifle Biomechanics

Rupture of the CrCL occurs when the tensile strength of the CrCL has been overcome as a result trauma and/or degenerative CrCL weakening. The stifle joint reaction force magnitude dependents on the combination of ground reaction forces (GRF) and muscle forces generated during the gait cycle and largely exceeds body weight, thus inducing high stresses on passive restraints such as the CrCL. Because of the tibial plateau slope orientation, tibial compression (during weight bearing or tibial compression test) generates a cranially oriented shear force that induces cranial tibial translation in CrCL deficient stifles. This shear force, the cranial tibial thrust (CrTT), is in part opposed by the CrCL. Accordingly, it has been suggested that CrTT magnitude depends on GRF magnitude and is likely amplified by greater tibial plateau slope angles (TPA). In a recent study, the mean TPA of dogs with CrCL rupture was significantly greater (by only 5.7°) than the mean TPA of dogs with intact CrCL. Considering the wide variation in natural TPA in both humans and dogs, and the influence of radiographic technique in TPA measurements, future prospective studies may be needed to confirm this data. Similarly, the influence of the knee flexors in protecting the CrCL has been suggested. Feeble flexors may be overpowered by the knee extensors, which could increase the CrCL contribution in preventing cranial tibial translation.

The actual mechanism by which tibial plateau leveling (TPL) provides functional stifle stability under load was recently investigated in vitro. The study demonstrated 1) that TPL stabilizes CrCL deficient stifles by converting CrTT into caudal tibial thrust (CaTT), making stifle stability depending on CaCL integrity, and 2) that CaCL strains increases with the magnitude of correction in cranial tibial plateau slope angle. This in turn may predispose the CaCL to fatigue failure. That study also showed that tibial plateau leveling is not necessary to restore functional stifle stability (the mean minimal tibial rotation angle providing stifle stability was 6.5° smaller than the mean pre-operative TPA). Because tibial plateau over-rotation increases CaCL stress, this smaller angle may represent the optimal angle of tibial plateau rotation providing joint stability in CrCL deficient stifles, while sparing the CaCL from excessive strains. This agrees with a recent report recommending that the tibial plateau rotation angle be 5° smaller than the original pre-operative TPA.



Pre-operative Measurement of the Tibial Plateau Angle

Measurement of the TPA is performed on lateral radiographs of the limb centered on the stifle joint. Radiographs should include the tibio-tarsal joint. A line joining the cranial and caudal edges of the medial tibial condyle materializes the tibial plateau slope. Next, the tibial functional axis is established from the center of the tibial plateau to the center of the talocrural joint. The TPA is the angle between the tibial slope and the perpendicular to the tibial functional axis.

Surgical Technique

Tibial Plateau Leveling Osteotomy: The following is a limited description of this patented surgical procedure. After routine anesthesia, joint exploration and CrCL debridement is conducted via a limited arthrotomy or arthroscopy. When appropriate, medial meniscal release is recommended to prevent secondary post-operative meniscal damages. The medial and caudal aspects of the proximal tibia are exposed through careful muscle retraction. A specialized patented armamentarium (Slocum Enterprises, Eugene OR), including a tibial jig and bi-radial saw blades, is then used to create a proximal tibial crescentic osteotomy. Saws of different diameters (24mm to 60mm) may be used to accommodate for a wide range of sizes of the proximal tibial metaphysis, without compromising the integrity of the tibial tuberosity. The orientation of the osteotomy may vary to address tibial torsional alignment as well as valgus or varus deformities according to pre-operative clinical and radiographic evaluation. The magnitude of the tibial plateau rotation is based on pre-operative TPA measurement. The TPA is converted into a chord length using the following formula: C = 2R(sin[a/2]), where C is the length of the chord intercepted by an angle a equal to the measured TPA, and R is the radius of the saw. Experimentally, a post-operative TPA of 6.5° was sufficient to provide stifle stability, while limiting excessive stresses on the CaCL (currently, the actual angle of tibial rotation recommended clinically is such that the post-operative TPA is 5°). Once the chord length corresponding to the TPA has been computed, matching reference marks can be etched on either side of the osteotomy line. The proximal tibial fragment is then rotated until the reference marks are aligned. Using a specially designed patented plate (Slocum Enterprises, Eugene OR) the tibial fragments are stabilized in the desired relationship. Routine closure in layers, including the arthrotomy, concludes the procedure.

Cranial Tibial Wedge Osteotomy: Since the TPLO is a patented procedure not readily available, this proceeding includes a description of the cranial tibial wedge osteotomy (CTWO), an early (not patented) version of this technique. The procedure is conducted as described above, until the tibial osteotomy step. Using a protractor, a tibial wedge (opening cranially) is etched immediately below the medial aspect of the tibial crest, then removed with a bone saw. The wedge angle equals the preoperative TPA reduced by 5° or 6° (e.g. ~ 20° for a preoperative TPA of 25°). The tibial fragments are then stabilized with a 2.7mm or 3.5mm, 6 or 7-hole DCP placed over the medial tibial surface. Careful contouring and pre-stressing are necessary to ensure proper limb alignment and fragment compression especially on the lateral surface. Routine closure in layers concludes the procedure.

Although CTWO is meant to neutralize the CrTT, and therefore should prevent cranial tibial subluxation under loading conditions, the relative effectiveness of this procedure vs. TPLO and its effect on CaCL stresses have yet to be reported. The long-term clinical outcome of CTWO was recently evaluated. Interestingly, the percentage of good/excellent results was 86%, which compares with reported results of more traditional intra-or extra-articular procedures. Complications however, were potentially more serious including tibial fracture and implant failure in 5% of the cases. One of the reported advantages of CTWO is faster return to weight bearing and performance despite a distinct tendency for post-operative stifle hyperextension. Unlike TPLO, the CTWO alters the normal femoro-patellar joint relationship, potentially causing patella baja unless the stifle is hyperextended. The clinical relevance of chronic stifle hyperextension after CWTO has yet to be determined.

Postoperative Management

Patients are discharged within 24 hours of surgery and post-operative pain is managed with NSAIDS as needed. Strict in-house confinement, along with short leash walks is recommended until radiographic evidence of clinical union. As with any other joint surgery, implementation of a controlled post-operative rehabilitation regimen is recommended to hasten recovery. Such protocols include passive ROM and stretching exercises, massage, as well as local application of heat and/or ultrasound. Similarly, swimming promotes muscle function and joint ROM. In order to address potential post-operative complications in a timely manner routine radiographic evaluation should be scheduled on a monthly basis until healing of the osteotomy site.

Complications

The TPLO procedure is somewhat more challenging than traditional procedures and may result in intra-operative complications including, popliteal artery laceration, iatrogenic fibular fracture, and intra-articular placement of the most proximal plate screw. Accurate tibial plateau correction is mandatory to prevent long-term complications. Indeed, while under-correction will fail to provide adequate postoperative joint stability, over-rotation may increase the risk of CaCL injury. Because such complications may be difficult to address, great attention should be paid to pre-operative TPA measurement as well as to intra-operative technical details. As with any osteosynthesis, postoperative complications include implant failure, non-union or mal-union and osteomyelitis. Other TPLO-related complications may be more challenging and include tibial crest fractures, patellar fracture, rotary instability and patellar luxation.

Anticipated Outcome

To date, most anecdotal reports have emphasized the rapid return to pre-injury limb function after TPLO. Based on subjective evaluations, functional recovery appears somewhat faster after TPLO than with other cruciate ligament procedures. Toe touching is usually observed within 2 weeks after surgery, followed by rapid improvement of limb function by 2 months. In a recent prospective clinical trial comparing TPLO and extra-articular techniques at 6 months, TPLO consistently yielded subjectively better outcomes for all parameters evaluated, including time to recovery, ROM, dog’s ability to sit normally, and postoperative complications. The effect of TPLO on limb function has been evaluated using force plate analysis. In contrast to previous clinical reports, no differences in peak vertical force at 2 and 6 months were found between intra-articular, extra-articular and TPLO techniques, suggesting no clear superiority of any procedure in restoring limb function. Reportedly, one of the most significant advantages of the TPLO procedure resides in its ability to control, unlike any other procedure before, the long-term progression of DJD. Additional comparative clinical studies are needed to confirm this remarkable observation.



1. Henderson RA, Milton JL: The tibial compression mechanism: A diagnostic aid in stifle injuries. J Am Anim Hosp Assoc 14:474-479, 1978

2. Read RA: Deformity of the proximal tibia in dogs. Vet Rec 111:295-298, 1982

3. Reif U, Hulse DA, Hauptman JG: Effect of tibial plateau leveling osteotomy on joint stability in the canine cruciate deficient stifle under axial tibial load – an in vitro study. Vet Surg 31(2):147-154, 2002

4 .Slocum B, Devine T: Cranial tibial thrust: A primary force in the canine stifle. J Am Vet Med Assoc 183:456-459, 1983

5. Slocum B, Devine T: Cranial tibial wedge osteotomy: A technique for eliminating cranial tibial thrust in cranial cruciate ligament repair. J Am Vet Med Assoc 184:564-569, 1984

6 .Slocum B, Devine T: Tibial plateau leveling osteotomy for repair of cranial cruciate ligament rupture in the canine. Vet Clin North Am 23:777-795, 1993

7. Watt PR, Sommerlad SM, Robins GM: Tibial wedge osteotomy for treatment of cranial cruciate rupture. Vet Surg 29(5):478, 2001

8. Warzee CC, Dejardin LM, Arnoczky SP, Perry RL: Effect of tibial plateau leveling on cranial and caudal tibial thrusts in canine cranial cruciate ligament deficient stifles - An in vitro experimental study. Vet Surg 30(3):278-286, 2001

[kelly]

Why do you call this procedure "unproven"?

[guest]

APPLICATIONS OF EVIDENCE-BASED MEDICINE: CRANIAL CRUCIATE LIGAMENT INJURY

Steven C. Budsberg, DVM, MS, Diplomate ACVS, University of Georgia, Athens, Georgia
ACVS Symposium Equine and Small Animal Proceedings
October 9, 2003


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The full text of the article is below.

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APPLICATIONS OF EVIDENCE-BASED MEDICINE: CRANIAL CRUCIATE LIGAMENT INJURY

Steven C. Budsberg, DVM, MS, Diplomate ACVS, University of Georgia, Athens, Georgia

Small Animal Proceedings

Evidence Based Medicine Track

Keywords: evidence, canine, studies, ligament, guidelines

From earlier papers, one can see that evidence-based medicine attempts to take the results of population studies and apply them to an individual animal. This is in stark contrast to traditional medical practice in which clinical experience (often from individual patients) is commonly used to define and defend the treatment of an entire group of patients with a similar problem. Nowhere can this paradox be seen more commonly than in surgical practice. Certainly, within veterinary orthopedics, clinical experience is still the driving force behind the vast majority of decisions made on the use of specific surgical procedures. This holds true for procedures recommended for cruciate injuries.

The process of constructing clinical practice guidelines from evidence-based medicine is to first define the question you would like to answer. Certainly, in this case while formulating a single question regarding cruciate injuries would appear easy, further examination reveals several significant questions that do need to be addressed. The first question to be asked for the sake of this discussion will be:

In dogs with cranial cruciate injuries and instability (patient or problem), which surgical procedure (intervention considered) will allow consistent return to normal clinical function postoperatively (intervention outcome) and is that procedure superior to other current techniques (comparison population)?

This question is probably too broad to answer fully at the present time, but we will use it as an example as it is the question that everyone really wants to know the answer to in veterinary orthopedic practice today. Other questions that need to be answered include: what is the best treatment recommendation for suspected or proven partial cruciate tears without instability? What is the best postoperative physical therapy regimen for dogs undergoing cruciate stabilization? Etc.

Next, we must find the evidence to attempt to answer the question. Searches were done through VIN, MEDLINE and CAB ABSTRACTS. While greater than 200 journal articles, proceedings and abstracts were evaluated, less than 20 provided relevant data for answering the aforementioned question.



Analysis of the Evidence

Limited evidence was available to help develop an answer to the question posed or providing data to construct any clinical practice guidelines. As stated previously when high-quality evidence is still not available for a given clinical question, explicit criteria for judging the quality of a study is mandatory. Each of these classes was used to catalog and evaluate the current available data.

Class I – Evidence derived from multiple, randomized, blinded, placebo-controlled trials: None available.

Class II – Evidence derived from high quality clinical trials using historical controls: Limited to none depending on the strictness of the criteria you apply. To my definition, no studies made it into this category.

Class III – Evidence derived from uncontrolled case series: This category is the majority of “peer reviewed data” available to the clinician today who attempts to understand the reasons for current recommendations stated for cruciate injuries. These studies varied from a study that a prospective comparison, but is not truly randomized, with limited subjective outcome measurements to uncontrolled case series with outcome measurements that ran the gambit from objective gait analysis to clinical impressions.

Class IV – Evidence derived from expert opinion, and/or extrapolated from bench research or physiologic studies: This category is unfortunately the most prominent source of information available today in regard to cruciate injuries and repair. In this review I have listed some of the more complete retrospective studies done to date, but none should be construed as providing extremely useful information to this discussion. Unfortunately, clinical practice has and will continue to be guided by these data in the absence of more reliable evidence. This review underscores the need for funding sources to support large, time consuming and expensive clinical trials.

In summarizing the evidence available, it is clear than no single procedure has enough data that allows any statements about potential for long term success in terms of clinical outcome. Furthermore, given the data available today, it is impossible to favor one procedure (TPLO, fibular head transposition, extracapsular suture stabilization, intracapsular ligament replacement) over another at this time.



Beckman SL, Wadsworth PL, Hunt CA, et al.: Technique for stabilizing the stifle with nylon bands in cases of ruptured anterior cruciate ligaments in dogs. J Am Anim Hosp Assoc 28:539-544, 1992

Budsberg SC, Verstraete MC, Soutas‑Little RWm, et al.: Force plate evaluation before and after stabilization of the stifle for cruciate injury. Am J Vet Res 49:1522-1524, 1988

Chauvet AE, Johnson AL, Pijanowski GJ, et al.: Evaluation of fibular head transposition, lateral fabellar suture, and conservative treatment of cranial cruciate ligament rupture in large dogs: a retrospective study. J Am Anim Hosp Assoc 32: 62-463, 1996

Conzemius MG, Gordon WJ, Besancon MF, et al.: The effect of surgical technique on limb function after surgery for cranial cruciate ligament disease in the labrador retriever. Vet Surg 31:479, 2002

Denny HR, Barr Ars: An evaluation of two ‘Over the Top’ techniques for anterior cruciate replacement in the dog. J Small Anim Prac 25:759-769, 1984

Denny HR, Goodship AE: Replacement of the anterior cruciate ligament with carbon fibre in the dog. J Small Anim Pract 21:279-286, 1980

Elkins AD, Pechman R, Kearney MT, et al: A retrospective study evaluating the degree of degenerative joint disease in the stifle joint of dogs following surgical repair of anterior cruciate ligament rupture. J Am Anim Hosp Assoc 27:533-540, 1991

Goetzee GL, Lubbe AM: A prospective study comparing two fascial reconstruction techniques to stabilize the cranial cruciate deficient stifle in the dog. Vet Comp Orth Trauma 8:82-90, 1995

Innes JF, Bacon D, Lynch C, et al: Long-term outcome of surgery for dogs with cranial cruciate ligament deficiency. Vet Rec 147:325-328, 2000

Innes JF, Barr ARS. Clinical natural history of the post surgical cruciate deficient canine stifle joint: Year 1. J. Small Anim Prac 39:325-332, 1998

Laitinen O.: Prospective clinical study of biodegradable poly-l-lactide implant as an augmentation device with fascia lata in cranial cruciate ligament repair in the dog: early results. Vet Comp Ortho Trauma 7:1-55, 1994

Lazar TP, Berry CR, deHaan JJ, et al.: Long-term comparison of stifle osteoarthritis in dogs with surgical repair of cranial cruciate ligament injury utilizing tibial plateau leveling osteotomy versus extracapsular stabilization. Vet Surg 30:498, 2001

Moore KW, Read RA: Cranial cruciate ligament rupture in the dog - a retrospective study comparing surgical techniques. Aus Vet J 72:281-285, 1995

Shires PK, Hulse DA, Liu W: The under-and-over fascial replacement technique for anterior cruciate ligament rupture in dogs: A retrospective study. J Am Anim Hosp Assoc 20:69-77, 1984

Slocum B, Slocum TD: Tibial plateau leveling osteotomy for repair of cranial cruciate ligament rupture in the canine. Vet Clin North Am [Sm An Prac] 23:777-795, 1993

Smith GK, Torq JS: Fibular head transposition for repair of cruciate-deficient stifles in the dog. J Am Vet Med Assoc 187:375-384, 1985








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Copyrighted for personal use only

[malernee]

FYI. This is the citation from a study that we did in experimental dogs comparing the MRIT (Flo) procedure with open arthrotomy versus arthroscopic debridement and minimally invasive suture placement. In a nutshell, the dogs with less invasive surgery weight-bear sooner. A result you would expect if cruciate surgery does not work.

Results of arthroscopic versus open arthrotomy for surgical management of cranial cruciate ligament deficiency in dogs.
Vet Surg 33[2]:146-53 2004 Mar-Apr

Hoelzler MG, Millis DL, Francis DA, Weigel JP
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37901-1071, USA. hoelzer@yahoo.com
OBJECTIVE: To evaluate postoperative morbidity in dogs after experimental cranial cruciate ligament transection and immediate stifle stabilization using an arthroscopically assisted or open arthrotomy technique. STUDY DESIGN: Experimental, prospective study. ANIMALS: Thirteen mature, healthy dogs. METHODS: Dogs were randomly assigned to 1 of 2 groups. Seven underwent open arthrotomy while 6 underwent arthroscopy of 1 stifle joint. Cranial cruciate ligaments were transected and debrided and all stifles were stabilized using 2 lateral extracapsular fabellar-tibial sutures. Minimally invasive suture placement was employed in the arthroscopy group. All animals were evaluated for 9 weeks using kinetic gait assessments, comfortable stifle range of motion measurements, thigh girth measurements, differential cell counts of synovial fluid, and subjective scores of behavior, limb use, and lameness. RESULTS: Significant differences in postoperative morbidity were observed during the 9-week postoperative period. Greater peak vertical force for 8 weeks (P=.015), vertical impulse for 6 weeks (P=.044), comfortable stifle range of motion for 9 weeks (P=.017), comfortable stifle flexion for 4 weeks (P=.005), and operative limb thigh circumference (P=.020) for 9 weeks were observed for the arthroscopy group. A trend towards a lower differential mean synovial polymorphonuclear cell count in the arthroscopy group was seen at 4 and 8 weeks postoperatively. No differences in subjective evaluation scores were noted. CONCLUSIONS: In this study population, significant differences were seen between the arthroscopy and arthrotomy groups for peak vertical force, vertical impulse, comfortable stifle range of motion, comfortable stifle flexion, and thigh circumference data. CLINICAL RELEVANCE: The results of this study suggest that short-term postoperative morbidity may be reduced in dogs receiving arthroscopic joint surgery with a limited approach for stifle stabilization as compared with a traditional open arthrotomy technique.

[malernee]

Comparison of Radiographic Arthritic Changes Associated with Two Variations of Tibial Plateau Leveling Osteotomy. A Retrospective Clinical Study
Vet Comp Ortho Trauma 18[1]:13-17 Feb'05 Retrospective Study 23 Refs

* J. A. Lineberger, D. A. Allen, E. R. Wilson, T A. Tobias, L. G. Shaiken, J. T. Shiroma, D. S. Biller, T W. Lehenbauer
* Mission MedVet, Mission, Kansas, U.S.A.
Osteoarthritis (OA) progresses in the canine cranial cruciate ligament (CCL) deficient stifle. Progression of OA is also documented in canine patients after various surgical repair techniques for this injury. We evaluated the radiographic arthritic changes in canine stifle joints that have sustained a CCL injury, and compared radiographic OA scores between Tibial Plateau Leveling Osteotomy (TPLO) surgery patients receiving a medial parapatellar exploratory arthrotomy for CCL remnant removal versus those receiving a limited caudal medial arthrotomy without removal of the CCL remnants. Medial/lateral and caudal/cranial stifle radiographs were obtained before surgery, immediately following TPLO surgery and at 7-38 months (mean 20.5) after surgery. Sixty-eight patients (72 stifles) were included in the study. The cases were divided into two groups. The patients in group 1 (n = 49 patients, 51 stifles) had a limited caudal medial arthrotomy, and patients in group 2 (n = 19 patients, 21 stifles) had a medial parapatellar open arthrotomy. A previously described radiographic osteoarthritis scoring system was used to quantify changes in both of the groups. The age, weight, OA scores, initial tibial plateau angle, final tibial plateau angle, and the change in angle were compared between the groups. The results showed that there was significantly less progression of OA in the group that had the limited caudal medial, arthrotomy, versus a medial parapatellar open arthrotomy. There was a significant advancement of the OA scores of patients that had TPLO surgery. [Summary]

[guest]

Stifle stabilization is a 1 billion dollar per year industry, but yet no method has been carefully investigated!


surgeons are often passionate about the specific technique they use. The most common procedures are TPLO, extra-capsular or intra-capsular. There is a fairly large literature on the subject of surgical technique, but the interesting thing is that most of the papers have almost no evidentiary value! Many are not clinical (e.g.; they are bench science) so that there is no direct relationship between the research and patient outcomes. Other papers have no control groups, artificially induced lameness or very small sample sizes.

When I say critical evaluation I mean of the scientific methodology. For example: Are the reviews of only clinical papers or do they include in vitro work? Randomized blinded trial beat observational studies independent of the subject matter. In human EBM reviews cost about $70,000 and are done mostly by a team that may have only one subject matter expert. The focus of EBM is the patient. The original developers wanted to do better by their patients, so their work has been to develop EBM to bring clinical researcher into the clinics that makes sense.

The Aragon and Budsberg study (below) has a very explicit (and repeatable) search strategy for finding papers. Their initial search netted 240 information sources, and 28 were relevant to the stifle stabilization technique. They used a classification system different and more general than the ADA primary research instrument we described . They focused primarily on the study design to classify studies into evidence categories. That was a reasonable approach in this case, as most of the 28 studies didn't warrant the more in-depth analysis of the ADA assessment. Their ranking, from best to worst is:

1. Evidence from multiple, RDBCT in the target species

2. Evidence from clinical trials with historical controls

3. Evidence form uncontrolled case series

4. Evidence from expert opinion or physiologic studies.

I suspect that the original intention of the paper was to do a meta analysis, that is, combine results from various studies to come to a conclusion about the best treatment method. However, the studies, by their scale didn't have much evidence so the goal of the paper was to evaluate the literature to get a summary of what was out there.
There have been discussions by professional about why Stifle treatment research has not been randomized , blinded, large sample sizes, etc and there are those that believe that EBM is not possible due to lake of money to make these studies possible. I don't think it is $$$. I think that it is an excuse. At least to some degree. There are grants and sources of money; also consumers are educating themselves and will soon demand scientific evidence behind recommendations for treating ACL.. I think the goal of most research in vet med has been "jumping hoops" - finishing a residency or academic advancement rather than quality answering of important clinical questions. It is easier to scan hospital records for a retrospective study than to obtain funding and do a randomized trial. Vets should stop using all the retrospective stuff for clinical decisions. It is really only good for designing larger, better studies. Getting back to the Aragon paper... Aragon and Budsberg found no level 1 or 2 studies in their literature search, and concluded that the use of evidence-based medicine in answering the current question yielded very little data to support any single ACL treatment. Although this doesn't tell us which ACL treatment to choose; it does tell us there is no scientific support for much of the propaganda that 1 single treatment is far superior to all others. As evidence-based medicine gains in popularity, the level of research expectations will increase producing more studies with evidentiary value. Likely, as the demand increases, more reviews will be published with overall recommendations to help with treatment recommendations on a day to day basis.

*****
Applications of Evidence-Based Medicine: Cranial Cruciate Ligament Injury Repair in the Dog; Carlos L. Aragon, DVM and Steven C. Budsberg, DVM, MS, Diplomate ACVS
Objective: To evaluate the literature reporting surgical interventions pertaining to canine cranial cruciate ligament (CCL) injury using an evidence-based medicine paradigm.

Study Design: Systematic literature review.

Methods: An on-line bibliographic search through Medline, PubMed, Veterinary Information Network, and Commonwealth Agricultural Bureau Abstracts was performed during August 2004. Two hundred and forty resources of information were identified. Studies were compared and evaluated with regard to study design (retrospective, prospective, randomization), surgical technique, short- and long-term follow-up, and evidence classification.

Results: Twenty-eight resources qualified to assist with evidence classification. No class I or class II studies were present, 5 studies were categorized as a class III and 23 studies were categorized as a class IV. Seventeen studies were retrospectively designed and 11 studies were prospectively designed. Proposed results ranged from a wide variety of subjective findings including clinical impression, radiographic analysis, synovial fluid analysis, gross pathology, and histopathology. Objective results, although infrequent, included force plate analysis and cadaveric biomechanical

Conclusions: At this time, the application of evidence-based medicine in analyzing the current available evidence suggests that there is not a single surgical procedure that has enough data to recommend that it can consistently return dogs to normal function after CCL injury. The requirement for assessing and categorizing the available evidence becomes increasingly important as more data becomes available and the quality of research improves.

Clinical Relevance: An evidence-based medicine paradigm did not provide sufficient evidence favoring 1 surgical technique for management of canine CCL injury.

[malernee]

Dogs face epidemic of knee-ligament injuries
Tuesday, April 11, 2006

By Kevin Helliker, The Wall Street Journal


A dog named Paddi was chasing a cat through a suburban Seattle neighborhood when suddenly she pulled up lame. So tender was Paddi's hind leg that her owner, physician Kevin Bulley, had to carry her home.

The diagnosis turned out to be a ruptured cruciate ligament, an injury that Dr. Bulley, a family practitioner, had associated only with humans. Cruciate ligaments hold in place the parts of the knee, and wrong turns on the athletic field often injure these cords.

The cost of fixing Paddi's knee was about $3,000. She had barely recovered from that surgery when the cruciate ligament in her other knee ruptured, prompting a second $3,000 procedure -- all for a mutt that Dr. Bulley and his family had adopted and grown to love. "She's the most expensive free dog I've ever heard of," says the physician.

Being an athlete is a well-known risk factor for cruciate-ligament injury. A larger -- but lesser-known -- risk factor is being a dog. The number of dog knees undergoing cruciate-ligament repair each year in America is estimated to now exceed 1.2 million. That's about five times the number of human procedures -- even though humans outnumber dogs in the U.S. by nearly five to one. And it's not as though dogs have more knees: The joint on their front legs are elbows that aren't vulnerable to the problem.

Dog owners often have no idea that this danger exists. Pennsylvania engineer Martin Yester, for example, investigated the medical history of his yellow Labrador, Sarah, before purchasing her as a puppy. Knee risks didn't come up -- until her cruciate ligament ruptured in December. Even though certain larger breeds have been shown to be more susceptible, "nobody talks about knee problems," says Mr. Yester.

The extraordinary rate of failure in dog knees is mystifying even to veterinarians. Is the prevalence of such canine injuries rising -- or are people less willing to let their pets hobble on three legs? "It's a bit of a mystery as to the cause," says Steven Budsberg, a veterinary surgeon who is director of clinical research at the University of Georgia College of Veterinary Medicine.

Today, cruciate-ligament repairs are the most common surgical procedures for injured or diseased dogs. And inside veterinary medicine, controversy is raging over the best treatments.

A relatively new technique, called tibial plateau leveling osteotomy, or TPLO, involves breaking and resetting the tibia, the long bone below the knee, in such a way as to obviate the need for a cruciate ligament. The surgery costs from about $2,500 to $5,000 per knee. That's about twice the cost of the conventional procedure, which like the human equivalent involves constructing a replacement ligament.

Many respected academic veterinary experts believe that TPLO offers a faster and fuller return of function. But published proof of that theory is lacking, prompting some to avoid the procedure. For instance, surgeons don't perform it at the University of Pennsylvania School of Veterinary Medicine, says Gail Smith, chairman of the department of clinical research. He calls TPLO "a fashionable procedure."

Still, TPLO now is used for an estimated 50 percent of cruciate-ligament procedures in the U.S., and by all accounts that percentage is growing.

Such treatments have helped fuel a doubling of the number of veterinary surgeons in the U.S. in the last decade to 1,219 from 660. It is also the largest factor in a near doubling of the average annual cost of veterinary surgery visits -- to $574 in 2004 from $289 in 2000, says the American Pet Products Manufacturers Association.

Like Dr. Bulley, hundreds of thousands of Americans are digging deep into their pockets each year for a surgery most never realized a dog might need. A November article in the Journal of the American Veterinary Medical Association estimated that Americans spent $1.32 billion to fix dog knees in 2003.

Without surgery, only 20 percent of dogs will regain normal function, says Dr. Michael Conzemius, an Iowa State University veterinary surgeon and a co-author of the November JAVMA article.

Even if Americans increasingly consider dogs to be part of the family, health insurers don't. According to the pet products industry and insurers, fewer than 3 percent of dog owners have purchased a medical policy for their pet.

A spokesman for the largest pet insurer, Veterinary Pet Insurance of Brea, Calif., says that cruciate-ligament problems in dogs accounted for nearly $4 million in claims in 2004, and that no other condition had a higher cost per claim.

One claimant was David Wright, a San Jose software engineer who several years ago bought two Labrador Retriever mixes for $80 each. The male, Sage, tore the cruciate ligaments in both of his knees in 2002. "The $80 dog became the $6,000 dog," says Mr. Wright.

Then the female, Kenya, wrecked both of her knees. Of the $12,000 that Mr. Wright spent on those surgeries, he says Veterinary Pet Insurance reimbursed him about $5,000. "Thank God I had that insurance," says Mr. Wright, adding that reimbursement for other, non-knee-related medical expenses already had exceeded the premiums he'd paid.

Unlike human knees, dog knees don't lock -- their back legs are always bent. That means the ligaments of the joint are tense whenever the animal is standing.

This helps explain why canine cruciate tears often occur over time in middle-aged dogs, while human ruptures can happen at any age, and almost always result from an acute twisting or turning of the joint. As in humans, the dog knee contains two cruciate ligaments, and the front-most ligament is likeliest to tear. In humans this is called the anterior ligament, in dogs the cranial ligament.

Few warnings exist for puppy purchasers or dog owners. The Web sites of breeding clubs typically make no mention of cruciate-ligament injuries while offering warnings and advice about screening for hip problems in dogs. The Web site of PetSmart Inc., the nation's largest retailer of pet supplies and services, offers advice about problematic hips in dogs, but not knees.

Diane Dahm, an orthopedic surgeon at the Mayo Clinic renowned for her knowledge of cruciate-ligament troubles in humans, says she isn't familiar with similar canine issues. "I'm aware of hip dysplasia in dogs," she says.

In fact, hips troubles aren't as common as canine knee problems. But hip problems have received attention in part because of a proven genetic component. Puppy buyers can demand certification of a family history free of hip dysplasia, a debilitating condition in which the ball and socket don't fit well together.

Some research suggests that cruciate-ligament tears also bear a genetic component. There always had been anecdotal evidence: For instance, Mr. Wright's two affected dogs are half siblings. An article in the January issue of the Journal of the American Veterinary Medical Association identified a gene that appears to predispose Newfoundlands to cruciate tears. Eventually, this discovery could lead to a test that would identify carriers of that gene, ideally enabling breeders to screen out problematic dogs.

Even now, some doctors say purchasers of puppies belonging to the larger, more at-risk breeds -- Labrador Retrievers, German Shepherds and such -- should ask about family history of cruciate-ligament disease. "Unfortunately, there's little you can do at this point except ask about it," says Dr. Conzemius.

For many pet owners, the thought of spending thousands of dollars on a dog knee remains laughable. "I'd never spend more than $300 on a dog, no matter how much I loved it," says Roger Holwick, whose eastern Kansas farm is home to eight dogs.

The fastest, an Australian Shepherd, has a bum leg that Mr. Holwick never considered getting fixed. "She rules the roost, and she doesn't even know she has a disability," he says.

[malernee]

Biomechanics of tibial plateau leveling of the canine cruciate-deficient stifle joint: a theoretical model
Vet Surg. February 2006;35(2):144-9.
Ron Shahar, Joshua Milgram
Laboratory of Biomechanics and Applied Anatomy, Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel. shahar@agri.huji.ac.il

Abstract
OBJECTIVE: To evaluate the effect of tibial plateau leveling on the biomechanics of the canine stifle. STUDY DESIGN: Analysis of a 3-dimensional (3-D) anatomically accurate theoretical model of the canine stifle. METHODS: A 3-D, 3-segment mathematical model of the normal canine stifle was modified to simulate the effect of rotation of the tibial plateau during tibial plateau leveling osteotomy (TPLO). The model examined the normal stifle, the stifle with a tibial plateau angle (TPA) of 0 degrees, and the stifle with a TPA of 5 degrees. Analysis of the models at 10 consecutive equally spaced positions during the stance phase yielded data such as ligament forces and joint reaction forces at each position. RESULTS: Rotation of the tibial plateau to a TPA of 0 degrees almost eliminates forces in the cranial cruciate ligament (CCL) throughout the stance phase. Rotation to a TPA of 5 degrees did not, however, substantially decrease the load in the CCL. Both procedures increased the load in the caudal cruciate ligament (CaCL). CONCLUSIONS: Cranial tibial thrust (CTT) is converted into caudal tibial thrust when the TPA is 0 degrees ; however, rotating the plateau to a TPA of 5 degrees does not eliminate the CTT. CLINICAL RELEVANCE: The TPLO procedure performed as currently recommended (rotating the tibial plateau to a TPA of 5 degrees) may not eliminate the CTT, but only reduce it. Both TPLO procedures evaluated here were found to increase the load in the CaCL.