Hollis G. Potter

The Microfracture Technique For The Treatment Of Articular Cartilage Lesions In The Knee: A Prospective Cohort Study

BACKGROUND Microfracture is a frequently used technique for the repair of articular cartilage lesions of the knee. Despite the popularity of the technique, prospective information about the clinical results after microfracture is still limited. The purpose of our study was to identify the factors that affect the clinical outcome from this cartilage repair technique. METHODS Forty-eight symptomatic patients with isolated full-thickness articular cartilage defects of the femur in a stable knee were treated with the microfracture technique. Prospective evaluation of patient outcome was performed for a minimum follow-up of twenty-four months with a combination of validated outcome scores, subjective clinical rating, and cartilage-sensitive magnetic resonance imaging. RESULTS At the time of the latest follow-up, knee function was rated good to excellent for thirty-two patients (67%), fair for twelve patients (25%), and poor for four (8%). Significant increases in the activities of daily living scores, International Knee Documentation Committee scores, and the physical component score of the Short Form-36 were demonstrated after microfracture (p < 0.05). A lower body-mass index correlated with higher scores for the activities of daily living and SF-36 physical component, with the worst results for patients with a body-mass index of >30 kg/m(2). Significant improvement in the activities of daily living score was more frequent with a preoperative duration of symptoms of less than twelve months (p < 0.05). Magnetic resonance imaging in twenty-four knees demonstrated good repair-tissue fill in the defect in thirteen patients (54%), moderate fill in seven (29%), and poor fill in four patients (17%). The fill grade correlated with the knee function scores. All knees with good fill demonstrated improved knee function, whereas poor fill grade was associated with limited improvement and decreasing functional scores after twenty-four months. CONCLUSIONS Microfracture repair of articular cartilage lesions in the knee results in significant functional improvement at a minimum follow-up of two years. The best short-term results are observed with good fill grade, low body-mass index, and a short duration of preoperative symptoms. A high body-mass index adversely affects short-term outcome, and a poor fill grade is associated with limited short-term durability.

Magnetic Resonance Imaging of Articular Cartilage in the Knee. An Evaluation with Use of Fast-spin-echo Imaging*

The purpose of this study was to demonstrate that specialized magnetic resonance imaging provides an accurate assessment of lesions of the articular cartilage of the knee. Arthroscopy was used as the comparative standard.Eighty-eight patients who had an average age of thirty-eight years were evaluated with magnetic resonance imaging and subsequent arthroscopy because of a suspected meniscal or ligamentous injury. The magnetic resonance imaging was performed with a specialized sequence in the sagittal, coronal, and axial planes. Seven articular surfaces (the patellar facets, the trochlea, the femoral condyles, and the tibial plateaus) were graded prospectively on the magnetic resonance images by two independent readers with use of the 5-point classification system of Outerbridge, which was also used at arthroscopy.Six hundred and sixteen articular surfaces were assessed, and 248 lesions were identified at arthroscopy. Eighty-two surfaces had chondral softening; seventy-five, mild ulceration; fifty-three, deep ulceration, fibrillation, or a flap without exposure of subchondral bone; and thirty-eight, full-thickness wear. To simplify the statistical analysis, grades 0 and 1 were regarded as disease-negative status and grades 2, 3, and 4 were regarded as disease-positive status. When the grades that had been assigned by reader 1 were used for the analysis, magnetic resonance imaging had a sensitivity of 87 per cent (144 of 166), a specificity of 94 per cent (424 of 450), an accuracy of 92 per cent (568 of 616), a positive predictive value of 85 per cent (144 of 170), and a negative predictive value of 95 per cent (424 of 446) for the detection of a chondral lesion. Interobserver variability was minimum, as indicated by a weighted kappa statistic of 0.93 (almost perfect agreement).With use of this readily available modified magnetic resonance imaging sequence, it is possible to assess all articular surfaces of the knee accurately and thereby identify lesions that are amenable to arthroscopic treatment.

Concentrated Bone Marrow Aspirate Improves Full-thickness Cartilage Repair Compared with Microfracture in the Equine Model

BACKGROUND The purpose of this study was to compare the outcomes of treatment with bone marrow aspirate concentrate, a simple, one-step, autogenous, and arthroscopically applicable method, with the outcomes of microfracture with regard to the repair of full-thickness cartilage defects in an equine model. METHODS Extensive (15-mm-diameter) full-thickness cartilage defects were created on the lateral trochlear ridge of the femur in twelve horses. Bone marrow was aspirated from the sternum and centrifuged to generate the bone marrow concentrate. The defects were treated with bone marrow concentrate and microfracture or with microfracture alone. Second-look arthroscopy was performed at three months, and the horses were killed at eight months. Repair was assessed with use of macroscopic and histological scoring systems as well as with quantitative magnetic resonance imaging. RESULTS No adverse reactions due to the microfracture or the bone marrow concentrate were observed. At eight months, macroscopic scores (mean and standard error of the mean, 9.4 + or - 1.2 compared with 4.4 + or - 1.2; p = 0.009) and histological scores (11.1 + or - 1.6 compared with 6.4 + or - 1.2; p = 0.02) indicated improvement in the repair tissue in the bone marrow concentrate group compared with that in the microfracture group. All scoring systems and magnetic resonance imaging data indicated that delivery of the bone marrow concentrate resulted in increased fill of the defects and improved integration of repair tissue into surrounding normal cartilage. In addition, there was greater type-II collagen content and improved orientation of the collagen as well as significantly more glycosaminoglycan in the bone marrow concentrate-treated defects than in the microfracture-treated defects. CONCLUSIONS Delivery of bone marrow concentrate can result in healing of acute full-thickness cartilage defects that is superior to that after microfracture alone in an equine model. CLINICAL RELEVANCE Delivery of bone marrow concentrate to cartilage defects has the clinical potential to improve cartilage healing, providing a simple, cost-effective, arthroscopically applicable, and clinically effective approach for cartilage repair.

Traumatic Tears of the Subscapularis Tendon Clinical Diagnosis, Magnetic Resonance Imaging Findings, and Operative Treatment

The study population consisted of 14 shoulders in 13 consecutive patients with surgically confirmed isolated subscapularis tendon tears. In all but three patients, the mechanism of injury was traumatic hyperextension or external rotation of the abducted arm. All patients reported pain and weakness in the affected shoulder. Physical findings revealed limited passive range of motion at maximal internal and external rotation due to pain, weakness of internal rotation of the shoulder, and tenderness in the region of the intertubercular groove. However, these findings did not conclusively point to the subscapularis tendon as the site of injury. Preop erative interpretation of magnetic resonance imaging studies was used to diagnose tears of the subscapu laris tendon in 14 shoulders and biceps tendon sublux ation or dislocation in 6 shoulders. On arthroscopic examination, one patient was found to have a partial- thickness tear that was treated with arthroscopic de bridement. Six shoulders had full-thickness tears of the subscapularis tendon, and seven shoulders had full- thickness tears associated with concomitant biceps tendon pathologic conditions, including subluxation, dislocation, or rupture. The full-thickness subscapu laris tendon tears were repaired via an open anterior approach to the shoulder through the deltopectoral groove. Associated biceps tendon injuries were treated with tenodesis of the tendon to the intertubercular groove. Our early followup results have shown that, with proper diagnoses and surgical treatments, pa tients have greatly decreased pain and marked im provement in shoulder function.

Biologic augmentation of rotator cuff tendon-healing with use of a mixture of osteoinductive growth factors.

BACKGROUND Clinical studies have demonstrated a high rate of incomplete healing of rotator cuff tendon repair. Since healing of such a repair is dependent on bone ingrowth into the repaired tendon, we hypothesized that osteoinductive growth factors would improve rotator cuff tendon-healing. METHODS Seventy-two skeletally mature sheep underwent detachment of the infraspinatus tendon followed by immediate repair. The animals received one of three treatments at the tendon-bone interface: (1) an osteoinductive bone protein extract on a Type-I collagen sponge carrier, (2) the collagen sponge carrier alone, and (3) no implant. The animals were killed at six and twelve weeks, and the repaired rotator cuff was evaluated with use of magnetic resonance imaging, plain radiographs, histologic analysis, and biomechanical testing. RESULTS A gap consistently formed between the end of the repaired tendon and bone in this model, with reparative scar tissue and new bone spanning the gap. Magnetic resonance imaging showed that the volume of newly formed bone (p < 0.05) and soft tissue (p < 0.05) in the tendon-bone gap were greater in the growth factor-treated animals compared with the collagen sponge control group at both time-points. Histologic analysis showed a fibrovascular tissue in the interface between tendon and bone, with a more robust fibrocartilage zone between the bone and the tendon in the growth factor-treated animals. The repairs that were treated with the osteoinductive growth factors had significantly greater failure loads at six weeks and twelve weeks (p < 0.05); however, when the data were normalized by tissue volume, there were no differences between the groups, suggesting that the treatment with growth factor results in the formation of poor-quality scar tissue rather than true tissue regeneration. The repairs that were treated with the collagen sponge carrier alone had significantly greater stiffness than the growth factor-treated group at twelve weeks (p = 0.005). CONCLUSIONS This model tests the effects of growth factors on scar tissue formation in a gap between tendon and bone. The administration of osteoinductive growth factors resulted in greater formation of new bone, fibrocartilage, and soft tissue, with a concomitant increase in tendon attachment strength but less stiffness than repairs treated with the collagen sponge carrier alone.

Magnetic Resonance Imaging After Total Hip Arthroplasty: Evaluation of Periprosthetic Soft Tissue

BACKGROUND The evaluation of periprosthetic osteolysis in patients who have had a total hip arthroplasty is challenging, and traditional imaging techniques, including magnetic resonance imaging and computerized tomography, are limited by metallic artifact. The purpose of the present study was to investigate the use of modified magnetic resonance imaging techniques involving commercially available software to visualize periprosthetic soft tissues, to define the bone-implant interface, and to detect the location and extent of osteolysis. METHODS Twenty-eight hips in twenty-seven patients were examined to assess the extent of osteolysis (nineteen hips), enigmatic pain (five), heterotopic ossification (two), suspected tumor (one), or femoral nerve palsy (one). The results were correlated with conventional radiographic findings as well as with intraoperative findings (when available). RESULTS Magnetic resonance imaging demonstrated the bone-implant interface and the surrounding soft-tissue envelope in all hips. Radiographs consistently underestimated the extent and location of acetabular osteolysis when compared with magnetic resonance imaging. Magnetic resonance imaging also disclosed radiographically occult extraosseous soft-tissue deposits that were similar in signal intensity to areas of osteolysis, demonstrated the relationship of these deposits to adjacent neurovascular structures, and allowed further visualization of hypertrophic synovial deposits that accompanied the bone resorption in twenty-five of the twenty-eight hips. CONCLUSIONS Magnetic resonance imaging is effective for the assessment of the periprosthetic soft tissues in patients who have had a total hip arthroplasty. While not indicated for every patient who has pain at the site of an arthroplasty, these techniques can be effective for the evaluation of the surrounding soft-tissue envelope as well as intracapsular synovial deposits and are more effective than radiographs for the detection and evaluation of osteolysis, thus aiding in clinical management.

T2 quantitation of articular cartilage at 1.5 T.

To evaluate sources of error when using a multiecho sequence for quantitative T2 mapping of articular cartilage at 1.5 T.

Cartilage Injury After Acute, Isolated Anterior Cruciate Ligament Tear Immediate and Longitudinal Effect With Clinical/MRI Follow-up

Background: Anterior cruciate ligament (ACL) tears have been implicated in the development of osteoarthritis. Limited data exist on longitudinal follow-up of isolated ACL injury. Hypotheses: All isolated ACL tears are associated with some degree of cartilage injury that will deteriorate over time. There is a threshold of magnetic resonance imaging (MRI)–detectable cartilage injury that will correlate with adverse change in subjective patient-reported outcome measures. Study Design: Cohort study, Level of evidence, 2. Methods: The authors conducted a prospective, observational analysis of 42 knees in 40 patients with acute, isolated ACL injury (14 treated nonoperatively, 28 by reconstruction) with imaging at the time of injury and yearly follow-up for a maximum of 11 years. Morphologic MRI and quantitative T2 mapping was performed with validated outcome measures. Results: All patients sustained chondral damage at initial injury. The adjusted risk of cartilage loss doubled from year 1 for the lateral compartment and medial femoral condyle (MFC) and tripled for the patella. By years 7 to 11, the risk for the lateral femoral condyle was 50 times baseline, 30 times for the patella, and 19 times for the MFC. There was increased risk of cartilage degeneration over the medial tibial plateau (MTP) (P = .047; odds ratio = 6.23; 95% confidence interval [CI], 1.03-37.90) and patella (P = .032; odds ratio = 4.88; 95% CI, 1.14-20.80) in nonsurgical patients compared with surgically treated patients. Size of the bone-marrow edema pattern was associated with cartilage degeneration from baseline to year 3 (P = .001 to .039). Each increase in the MFC Outerbridge score resulted in a 13-point decrease in the International Knee Documentation Committee subjective knee score (P = .0002). Each increase in the MTP resulted in a 2.4-point decrease in the activity rating scale (P = .002). Conclusion: All patients with acute, traumatic ACL disruption sustained a chondral injury at the time of initial impact with subsequent longitudinal chondral degradation in compartments unaffected by the initial “bone bruise,” a process that is accelerated at 5 to 7 years’ follow-up.

Augmentation of Tendon Healing in an Intraarticular Bone Tunnel with Use of a Bone Growth Factor

We hypothesized that an exogenous bone growth factor could augment healing of a tendon graft in a bone tunnel in a rabbit anterior cruciate ligament-reconstruction model. Seventy rabbits underwent bilateral anterior cruciate ligament reconstructions with a semitendinosus tendon graft. One limb received a collagen sponge carrier vehicle containing a mixture of bone-derived proteins while the contralateral limb was treated with either no sponge or a sponge without bone-derived proteins. The reconstruction was evaluated at 2, 4, or 8 weeks with histologic, biomechanical, and magnetic resonance imaging analysis. Histologic analysis demonstrated that specimens treated with bone-derived proteins had a more consistent, dense interface tissue and closer apposition of new bone to the graft, with occasional formation of a fibrocartilaginous interface, when compared with control specimens. The treated specimens had significantly higher load-to-failure rates than did control specimens. Treatment with bone-derived proteins resulted in an average increase in tensile strength of 65%. The treated specimens were stronger than control specimens at each time point, but the difference was greatest at 8 weeks. On the basis of signal characteristics and new bone formation, magnetic resonance imaging was useful for predicting which limb was treated, the site of failure, and the limbs with higher load-to-failure values. This study demonstrates the potential for augmenting tendon healing in an intraarticular bone tunnel using an osteoinductive growth factor.

Fresh stored allografts for the treatment of osteochondral defects of the knee.

BACKGROUND Osteochondral allograft reconstruction of articular cartilage defects is a well-established cartilage repair strategy. Currently, fresh osteochondral allograft tissue is commercially available to clinicians approximately thirty days following graft harvest. Little clinical information is available on the outcome of patients who have been treated with fresh allografts stored for several weeks or more. The purpose of this study was to prospectively analyze the clinical outcome and graft morphology of patients who received fresh, hypothermically stored, allograft tissue for the treatment of symptomatic chondral and osteochondral defects of the knee. METHODS Nineteen patients with symptomatic chondral and osteochondral lesions of the knee who were treated with fresh osteochondral allografts between 1999 and 2002 were prospectively followed. The mean age at the time of surgery was thirty-four years. Validated outcomes instruments (the Activities of Daily Living Scale and the Short Form-36) were used; all patients must have had a baseline functional score prior to surgery and a minimum two-year follow-up evaluation. All grafts were obtained from commercial vendors; the mean preimplantation storage time of the graft was thirty days (range, seventeen to forty-two days). The mean lesion size was 602 mm(2). Magnetic resonance imaging was used to evaluate the morphologic characteristics of the implanted grafts. RESULTS The mean duration of clinical follow-up was forty-eight months (range, twenty-one to sixty-eight months). The mean score (and standard deviation) on the Activities of Daily Living Scale increased from a baseline of 56 +/- 24 to 70 +/- 22 at the time of the final follow-up (p < 0.05). The mean Short Form-36 score increased from a baseline of 51 +/- 23 to 66 +/- 24 at the time of final follow-up (p < 0.005). With the numbers studied, we could not correlate graft storage time, body mass index, lesion size, lesion location, or patient age with the functional outcome scores. At a mean follow-up interval of twenty-five months, cartilage-sensitive magnetic resonance imaging demonstrated that the normal articular cartilage thickness was preserved in eighteen implanted grafts, and allograft cartilage signal properties were isointense relative to normal articular cartilage in eight of the eighteen grafts. Osseous trabecular incorporation of the allograft was complete or partial in fourteen patients and poor in four patients. Complete or partial trabecular incorporation positively correlated with Short Form-36 scores at the time of follow-up (r = 0.487, p < 0.05). CONCLUSIONS Fresh osteochondral allografts that were hypothermically stored between seventeen and forty-two days were effective in the short term both structurally and functionally in reconstructing symptomatic chondral and osteochondral lesions of the knee. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.