Kaplan Lab - Recent Talks

Recent Talks

Prevalence and Variance of Knee Injuries in Elite College American Football Players – Presented at the International Society of Arthroscopy, Knee Surgery, and Orthopedic Sports Medicine (ISAKOS) (Florence, Italy 5/2007)

There is a high prevalence of knee injuries in elite intercollegiate American Football
players, with the most common type of injury varying by position. 332 elite American football players were evaluated at the NFL combine. All players had radiographic examinations including plain radiographs and/or MRI when necessary. Players were categorized by position for analysis and specific trends.

53.9% of players had history of knee injury (total of 201 knee injuries). 25.9% of players had a history of knee surgery (total of 86 players with knee surgery). Most common injuries were: MCL injury (22%), ACL/PCL injury (11.4%), meniscal injury (10.5%) and tendonitis (5.7%). Knee injuries were most common in lineman and tight ends. Knee surgery was most common in running backs and linebackers.

Knee injuries are common injuries in elite collegiate football players with a quarter undergoing surgical procedures. Definitive trends are seen in the types of injuries/ player position.

Knee Injury Chart

Assessment of Articular Cartilage Damage from Mechanical Chondroplasty – Presented at the European Society of Sports Tramatology, Knee Surgery, and Arthroscopy (ESSKA) (Innsbruck, AU 5/2006) and American Orthopedic Society for Sports Medicine (AOSSM) (Hershey, PA 6/2006)

The purpose of this study was to determine the depth of penetration from mechanical chondroplasty and metabolic consequences of this procedure on the remaining articular cartilage. Mechanical chondroplasty was performed in-vitro on a portion of fresh, grade 1 or 2, articular cartilage from eight human knee arthroplasty specimens. Treated and control (untreated) explants (~30 mg) were cut from the cartilage. The explants were divided into day 1 and day 4 groups, placed separately in a 48 well plate containing media and incubated at 37°C for 24 hours. After the 24 hour incubation, the explants were weighed on day 1 and 4 explant media was removed, and tested for total proteoglycan synthesis and aggrecan synthesis. At time zero, two sets (2.6mm each) of treated and control cartilage slices were cut using a precision saw. One set was stained for confocal laser microscopy using a cytotoxicity stain to determine cell viability. The second set was stained with H&E to determine depth of penetration.

The average depth of penetration was 252.8µ ± 78. There was no significant difference (p>0.25) between total proteoglycan synthesis for control versus treatment groups at day 1 or 4. Aggrecan synthesis was significantly reduced at day 1 when normalized for tissue weight (p=0.019) and dsDNA (p=0.004). At day 4, no significant difference was detected. Confocal laser microscopy did not show cell death below the zone of treatment. There was no significant metabolic consequence caused by chondroplasty to the remaining articular cartilage and the zone of injury was limited to the treatment area.

Clinical Relevance: Mechanical chondroplasty causes no significant metabolic consequences to articular cartilage under these conditions.

Hip versus Knee Articular Cartilage: Differences in Proliferative and Metabolic Activity – Presented at the International Cartilage Research Society (ICRS) (San Diego, CA 1/2006)

Arthroscopy has only recently been significantly implemented for hip pathology. In addition, there has been an increase in the demand for articular cartilage by research centers, which are currently limited to utilizing only knee articular cartilage. In spite of this demand for knowledge about hip articular cartilage, differences in metabolic and proliferative activity of osteoarthritic articular cartilage from femoral heads and femoral condyles, remains relatively unexplored.

Grade zero to one (ICRS grade) articular cartilage was harvested from less involved areas within hip and knee specimens following arthroplasty. Glycosaminoglycan (GAG) synthesis of explants and cell cultures was assessed using 35S incorporation. Cultured proliferation was also evaluated.

Knee chondrocytes showed a 24.7% increase in proliferation over hip chondrocytes in monolayer (p=.0003). The GAG synthesis in monolayer hip chondrocytes was 346.7% greater than knee chondrocytes (p=.0006). In explant cultures, there was a 62.3% difference in GAG synthesis when adjusted for explant cellularity (p =.07). The cellularity (cells/mg of tissue) of the explants, however, did not show relevant differences (p = .26).

The results indicate that the histological composition of the articular cartilage may be similar in the two joints, but metabolic and proliferative characteristics are distinct. In addition, there are significant differences in osteoarthritic hip and knee cartilage metabolism in vitro, and nearly significant differences ex vivo. These differences are important when utilizing these sources for articular cartilage research in addition to being clinically important.

Arthoscopic Capsular Plication: A Cadaveric Analysis of Volume Reduction – Presented at the Arthroscopy Association of North America (AANA) Annual Meeting (Vancouver, Canada 5/2005)

Surgical procedures for multidirectional instability attempt to reduce capsular redundancy and volume. Arthroscopically, this can be accomplished with thermal capsular shrinkage or capsular plication. Previous studies have started to quantify the amount of volume reduction with various techniques, open or arthroscopic. This study quantifies the volume reduction obtained with varying amounts of capsular plication preformed arthroscopically.

Six fresh frozen cadaveric specimens were obtained. Specimens were rejected if a rotator cuff tear was present. The volume of each shoulder joint will be measured under three conditions: no capsular shift, 5 mm capsular shift, and 10 mm capsular shift. For each shift, four sutures were be placed arthroscopically, two anteriorly and two posteriorly. Repeated measures were used to confirm the validity of the measurements. Data will be analyzed with parametric and non-parametric tests.

The average percentage of volume reduction at 5 mm of capsular plication from control was 14.5 % (range 8.6-19.2). Percentage reduction of between the 5 mm and 10 mm plication groups averaged 18.3 % (range 13-27.9). The percentage of volume reduction from control to 10 mm of capsular plication averaged 30.2% (range 23 – 39.7). Statistical significance was found with both parametric (p<0.0001) and non-parametric tests (p<0.0313). From the capsular reduction data, an equation of capsular reduction per amount of capsulorhaphy was computed.

The current study found that capsular volume reduction was related to the amount of capsular plication with reproducible results. A linear relationship between volume and plication was determined. This information may have clinical implication in the surgical setting to determine the potential number of sutures and amount of tissue plication needed for the presenting amount of laxity.

Metabolic Changes on Articular Cartilage on Thermal Environment – Presented at the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Hollywood, FL 4/2005

Thermal treatment modalities including laser and radiofrequency methods have been utilized to perform chondroplasty on partial thickness articular cartilage defects. The ability to clearly define the amount of thermal stress necessary to achieve the desired clinical response of the tissue is critical to establishing whether a “thermal safe zone” exists which would enable safe and efficacious treatment. The purpose of this experiment was to visualize the thermal “smoothing” (change in fibrillation) in actual time sequence and evaluate the metabolic consequence (Figure 1) of this thermal exposure.

With the approval of our institutional review board (IRB) for this project, six arthritic articular cartilage (grade 2 and 3 Outerbridge classification) specimens were obtained secondary to total knee arthroplasty and sectioned. A thermally-regulated tissue culture dish was programmed to ramp from 45 to 60 degrees C over 90 seconds, and then to hold the temperature at 60 degrees for 10 seconds. This thermal exposure (10 seconds at 60 degrees) was determined to elicit a visual change of cartilage fibrillation (Figure 2). Red-green histological staining was used to identify cell death, and metabolic testing (performed in triplicate) included MTT conversion, and proteoglycan synthesis. Specimens were tested at time zero and one week after treatment. The greatest decrease in metabolism of heated specimens versus control was in proteoglycan synthesis at time 0. Based on a repeated measures analysis of variance we found that there was a difference between the heated and control groups of 95.5% (p=0.0003) at time 0, and 78.3% (p=0.0008) at day 7 for proteoglycan synthesis. MTT conversion was reduced by 34.9% (p=0.0299) at time 0, and 50.6% (p=0.0073) at day 7.

There was a marked decrease in metabolic viability both at time zero and one week following treatment at this thermal exposure. However, there was no significant change observed in viability indicators over the one week period. At this degree of thermal exposure, there was definitive metabolic change under these experimental conditions.

In Vivo Imaging in Orthopedics and Tissue Engineering Applications - Presented at University of Pittsburgh, Pittsburgh, PA

The talk described quantitative in vivo imaging for orthopedic and tissue engineering applications. The purpose and use of thermal energy along with different techniques and probes was described. The talk reviewed the effect of distance, temperature and thermal stress studies on articular cartilage and their metabolic effects. A new robotic protocol was introduced that may be used to quantify these parameters.

Effects of Temperature at Variable Times on Arthritic Vs Non Arthritic Cartilage- Presented at University of Pittsburgh, Pittsburgh, PA

The talk focused on the effect of temperature and exposure time on articular cartilage. The study of thermal stress and smoothing due to different temperatures and times constraints, using both arthritic and non-arthritic cartilage was discussed.

Thermally-induced Morphological Change in Fibrillated Articular Cartilage- Presented at the UW-Madison Medical School.

The thermal chondroplasty literature was reviewed, including both lasers and radiofrequency techniques. Many studies are presented including, evaluating the time-temperature relationship of monopolar and bipolar radio frequency probes and their individual characteristics, distance of these probes to cartilage and how it effects thermal stress, time and temperature effects of thermal stress, thermal recovery, smoothing study and arthritic compared to non-arthritic cartilage.

The Effect of Thermal Stress on Articular Cartilage

The literature was reviewed that related to effect of radiofrequency-generated thermal energy on arthritic and non-arthritic articular cartilage. Metabolic activity after thermal stress (exposure time and varied temperature) was discussed.