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Biomedical subjects

Patrick E Greis

Publications and source records attributed to Patrick E Greis.

At least 19 recordsLinked to original sources
PubMed2006

Effect of lateral meniscal allograft sizing on contact mechanics of the lateral tibial plateau: an experimental study in human cadaveric knee joints.

BACKGROUND: A mismatch of the original lateral meniscus and a lateral meniscus allograft by inaccurate preoperative radiographic sizing can have significant consequences on ultimate function. HYPOTHESIS: The size of a lateral meniscal allograft affects the contact mechanics of the femoral condyle on the tibial plateau. STUDY DESIGN: Controlled laboratory study. METHODS: Four right and 2 left knees were tested as intact joints, after meniscectomy, and after replantation with the original menisci and 16 right or 9 left human, fresh-frozen lateral meniscal allografts, respectively. The allografts were allocated into 7 groups according to their outer and inner anteroposterior and mediolateral diameters. Biomechanical testing was performed as compressive loadings with constrained motions in extension and 30 degrees of flexion. Measurements were done with Fuji pressure-sensitive films for contact parameters of the direct femorotibial and meniscotibial contact. RESULTS: Oversized lateral meniscal allografts led to greater forces across the articular cartilage, whereas undersized allografts resulted in normal forces across the articular cartilage but greater forces across the meniscus. Two undersized transplants failed. Most of the contact parameters of allografts 10% smaller or larger than the original menisci were in the range of the intact knees. The knees after meniscectomy showed greater forces of the direct femorotibial contact areas than did the intact knees and the knees with the replanted original menisci. The contact mechanics of the knees with the replanted original menisci were close to normal. CONCLUSION: The size of a lateral meniscal allograft has a significant effect on the contact mechanics of the tibial plateau. CLINICAL RELEVANCE: Preoperative radiographic sizing needs to be performed precisely to identify a suitable lateral meniscal allograft. A mismatch may be the reason for failure of the allograft or subsequent development of degenerative changes. A mismatch on graft selection of less than 10% of the size of the original meniscus may be acceptable.

Aged↗
PubMed2006

Clinical outcomes following osteochondral autologous transplantation (OATS).

This study evaluated the clinical outcome in 21 patients (22 knees) undergoing osteochondral autologous transplantation (OATS) in the knee over a 5-year period. Sixteen knees in 15 patients were available for follow-up at an average of 40 months after the procedure. The clinical outcome was analyzed using the IKDC and Knee and Osteoarthritis Outcome Score (KOOS) evaluation forms, a subjective questionnaire, and a clinical examination. At final follow-up, the average KOOS result for pain was 80.6 (range: 56-94), symptoms 53.6 (range: 25-71), function of activities of daily living 93.4 (range: 79-100), function of sports and recreational activities 65.3 (range: 20-100), and quality of life 51.0 (range: 6-88). The average IKDC score was 68.2. On our subjective questionnaire, the average preoperative grade given was 3.1 (range: 1-7) with an improvement at the most recent follow-up to a grade of 8.0 (range: 5-10) (P < .00001). Thirteen (86%) patients reported that they would have the surgery again if they had to make the decision a second time. Age did not correlate with subjective results on the IKDC evaluation (P = .7048) or score difference on our questionnaire (P = .9175). This procedure provides an option for articular resurfacing of the femoral condyles for focal areas of chondral defects with promising results regarding subjective improvement.

Activities of Daily Living↗
PubMed2006

Outpatient management of continuous peripheral nerve catheters placed using ultrasound guidance: an experience in 620 patients.

BACKGROUND: Continuous peripheral nerve block (CPNB) is an optimal choice for analgesia after orthopedic procedures, but is not commonly used in outpatients because of concern regarding the possibility of catheter-related complications. In addition, it may be difficult to provide adequate patient access to physicians in this setting. We present 620 outpatients who were treated with CPNB using an established protocol. METHODS: All catheters were placed using direct ultrasound visualization. These patients received extensive oral and written preoperative instruction and were provided continuous telephone access to the anesthesiologist during the postoperative period. All patients were also contacted at home by telephone on the first postoperative day. In addition, each patient was seen and examined by the surgeon within 2 wk of hospital discharge. RESULTS: Of the 620 patients, there were 190 interscalene (brachial plexus), 206 fascia iliaca (femoral nerve), and 224 popliteal fossa (sciatic nerve) catheters. Two patients (0.3%) had complications related to the nerve block. In both of these patients, the symptoms resolved within 6 wk of surgery. Twenty-six patients (4.2%) required postoperative interventions by the anesthesiologist. One patient returned to the hospital for catheter removal. CONCLUSIONS: In this large series of outpatients treated with CPNB, there were surprisingly few interventions requiring an anesthesiologist. Likewise, patients were able to manage and remove their catheters at home without additional follow-up. This suggests that with adequate instruction and telephone access to health care providers, patients are comfortable with managing and removing CPNB catheters at home.

Adolescent↗
PubMed2006

Early application of negative work via eccentric ergometry following anterior cruciate ligament reconstruction: a case report.

STUDY DESIGN: Case report. OBJECTIVES: To present a progressively increasing negative-work exercise program via eccentric ergometry early after anterior cruciate ligament reconstruction (ACL-R) and to suggest the potential of negative work to amplify the return of quadriceps size and strength. CASE DESCRIPTION: The patient was a 26-year-old highly active recreational athlete who sustained an ACL tear while skiing in January 2004 and then again while skiing in February 2005. This individual underwent an arthroscopically assisted ACL-R with a double-loop semitendinosusgracilis autograft initially, then a patellar tendon autograft following his ACL graft rupture. Beginning within 3 weeks after surgery, a progressive negative-work exercise program was initiated using an eccentric ergometer. The patient completed 31 training sessions of 5 to 30 minutes in duration over a 12-week period following the ACL-R and 33 training sessions of the same frequency and duration following the ACL revision. OUTCOMES: Following ACL-R, quadriceps volume increased 28% (involved lower extremity) and 14% (uninvolved lower extremity) during the 12-week training program. Following revision, quadriceps volume returned to similar levels at the same postoperative period as those achieved after the initial surgery (2% less on the involved side and 2% greater on the uninvolved side). Quadriceps strength, 15 weeks after ACL-R, exceeded preoperative measures by an average of 20% (involved) and 14% (uninvolved). Quadriceps strength after ACL revision exceeded all previous measures. DISCUSSION: This case report suggests that if gradually and progressively applied, negative work via eccentric ergometry can be both safe and efficacious early after ACL-R. Eccentric exercise may mitigate the prevalent muscle size and strength deficits commonly observed after ACL-R. The results of this case suggest a need for continued research with early negative work interventions following ACL-R.

Adult↗
PubMed2005

The use of a single osteochondral autograft plug in the treatment of a large osteochondral lesion in the femoral condyle: an experimental study in sheep.

BACKGROUND: The use of osteochondral autograft plugs can be restricted because of limited amount of donor material. HYPOTHESIS: A small osteochondral autograft plug placed in the center of a large defect in a sheep femoral condyle will yield results superior to either an untreated or a bone-grafted defect. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve adult sheep underwent bilateral hindlimb surgery. On 1 limb, a 6-mm circular osteochondral autograft plug was placed in the center of a 10-mm circular defect in the medial femoral condyle. The gap between the plug and the condyle was filled with bone graft. On the contralateral side, the defect was either left untreated or filled with bone graft (control specimens). Animals were studied at 6 and 12 months under gross examination, high-resolution radiography, and histologic evaluation. RESULTS: At 6 months, 4 of 6 plugs healed and showed good maintenance of the joint surface and cartilage viability in the plugs. One plug fractured and resorbed, and 1 plug settled but healed. At 1 year, all 5 plugs healed, 1 having settled slightly (1 animal died earlier). The plug specimens showed better maintenance of the condyle contour at both times, and the central plug had hyaline-appearing cartilage. The control specimens were more irregular, had a fibrocartilage fill, and appeared flatter, although no gross cavitation or collapse was indicated. Composite cartilage scores on histologic evaluation were significantly higher for the plug specimens after 6 months (P = .02) and 1 year (P = .036) compared with controls. CONCLUSION: At 6 months and 1 year, a 6-mm osteochondral plug placed in a 10-mm defect better preserved the articular surface and contour of the condyle compared to untreated or bone-grafted defects. CLINICAL RELEVANCE: Osteochondral autograft plugs may be able to treat larger articular lesions without complete fill of the defect.

Animals↗
PubMed2005

Osteochondral injury to the mid-lateral weight-bearing portion of the lateral femoral condyle associated with patella dislocation.

We report on a series of 7 patients who presented with patella dislocation and were found to have osteochondral fracture (OCF) of the weight-bearing portion of the lateral femoral condyle either through preoperative studies or by identification of the lesion during arthroscopy. Treatments included open reduction and internal fixation, debridement, and microfracture of the lateral femoral condyle. Although not as common as osteochondral injuries to the medial facet of the patella and the anterior lateral portion of the lateral femoral condyle, osteochondral injury to the weight-bearing portion of the mid-lateral femoral condyle does occur with patella dislocation and was recognized in these 7 patients. The surgeon who treats known patellofemoral dislocations should be aware of this uncommon lesion to ensure detection and appropriate treatment. Also, in the case of uncertainty about the mechanism of injury, recognition of this lesion should heighten suspicion of patellofemoral dislocation.

Adolescent↗
PubMed2005

The effects of semitendinosus and gracilis harvest in anterior cruciate ligament reconstruction.

PURPOSE: There is significant debate concerning the morbidity of hamstring harvest for use during anterior cruciate ligament (ACL) reconstruction. We hypothesized that harvest of the semitendinosus and gracilis tendons for ACL reconstruction would result in no measurable hamstring weakness, but that abnormalities of the semitendinosus and gracilis muscle would be observed on magnetic resonance imaging (MRI) scans. TYPE OF STUDY: Case series. METHODS: Nine patients undergoing ACL reconstruction with doubled semitendinosus and gracilis tendons had MRI cross-sectional area measurements of both limbs made from axial images and muscle contour was studied on coronal images at 3 and 12 months. The semitendinosus, semimembranosus, gracilis, sartorius, and biceps muscles were evaluated. Isokinetic testing was performed on the operative and nonoperative legs at 60 degrees and 180 degrees per second at 6 and 12 months postoperatively. RESULTS: The gracilis cross-sectional area at 1 year averaged 2 cm2 on the operative side and 3.7 cm2 on the contralateral side. The semitendinosus averaged 2.1 cm2 on the operative side and 6.6 cm2 on the contralateral side at 1 year. Both of these differences were statistically significant (P < .05). In most cases, the semitendinosus muscle was retracted. Distally, the gracilis and occasionally the semitendinosus were blending with the gastrocnemius or sartorial fascia. The gracilis and semitendinosus in 1 case extended to near the original attachment site. Hamstring strength testing revealed a 26% deficit on the operative side at 60 degrees/second at 6 months and 16% at 180 degrees/second. At 12 months the mean 60 degrees/second deficit was 21% and the deficit at 180 degrees/second was 13%. CONCLUSIONS: At 1 year, the semitendinosus and gracilis muscles showed significant and persistent atrophy on the operative side and frequent retraction of the semitendinosus muscle belly. There were also hamstring strength deficits persisting at 1 year after the use of the tendons for ACL reconstruction. LEVEL OF EVIDENCE: Level IV.

Adult↗
PubMed2005

Surgical treatment options for patella tendon rupture, Part I: Acute.

Patella tendon rupture is a debilitating injury. Prompt diagnosis and treatment is essential to prevent retraction of the patella with subsequent adhesions and quadriceps contractures. In a young patient with an acute rupture, primary repair usually is possible with various methods described to protect the repair. In acute injuries with inadequate tissue, augmentation with hamstring tendons or allograft generally is necessary. Because of the different types of rupture and the possibility for poor quality tissue, the surgeon should always be prepared to combine different techniques to obtain tthe best repair. Continuous passive motion generally can be initiated early with a secure repair. In patients with a patella tendon ruptured that is promptly diagnosed, securely repaired, and followed closely through their rehabilitation, good results can be expected.

Contraindications↗
PubMed2005

Surgical treatment options for patella tendon rupture, part II: chronic.

Patella tendon rupture is a debilitating injury that often occurs in the setting of preexisting tendon degeneration. Prompt diagnosis and treatment is essential to prevent retraction of the patella with subsequent adhesions and quadriceps contractures. In the setting of a chronic rupture, augmentation with hamstring tendons or allograft reconstruction generally is necessary. Patients who undergo delayed repair are at risk for a compromised result secondary to loss of full knee flexion and decreased quadriceps strength, although a functional extensor mechanism is likely to be reestablished. Overall the results of chronic repair are less satisfactory than the acute repair, but still provide an extensor mechanism for the patient and thus provide function.

Chronic Disease↗
PubMed2003

Effects of initial graft tension on knee stability after anterior cruciate ligament reconstruction using hamstring tendons: a cadaver study.

PURPOSE: Tension degradation within hamstring grafts and anterior knee laxity were analyzed in a cadaveric anterior cruciate ligament (ACL) reconstruction model undergoing cyclic motion. It was hypothesized that suture fixation of a hamstring graft would lose tension during cycling initially and then stabilize, and that anterior knee laxity would increase as tension was lost. Hamstring grafts fixed under 3 different loads were evaluated to determine how initial graft tension affected knee laxity after cyclic motion. TYPE OF STUDY: Cadaveric biomechanical analysis. METHODS: Eighteen pairs of fresh-frozen hamstring tendons were tested on 2 cadaveric knees undergoing ACL reconstruction. The hamstring pairs were separated equally and randomly into one of 3 tension groups: 68 N (15 lb), 45 N (10 lb), and 23 N (5 lb). The loads were applied to the graft at 30 degrees of flexion, and the grafts were secured to the tibia with a suture and post technique. The knee was then cycled 1,000 times using an Instron machine (Instron, Canton, MA) through a range of motion between 0 degrees to 90 degrees. Constant monitoring and recording of graft tension was performed. A KT-1000 (Medmetrics, San Diego, CA) was performed (1) on the intact knee, (2) after ACL excision, (3) after ACL reconstruction and initial graft fixation, and (4) at the completion of the 1,000 cycles. An analysis of variance test was used to evaluate data. RESULTS: The tension within the grafts after 1,000 cycles decreased to 34.5 N (7.6 lb), 16.8 N (3.7 lb), and 15.4 N (3.4 lb) from the preloads of 68, 45, and 23 N, respectively (P <.05 in all cases). This represented an average decrease of 50.2% of the initial tension after 1,000 cycles. Manual-maximum KT testing of the intact knees was 5.8 +/- 0.3 mm, and after ACL excision was 13.2 +/- 0.9 mm. KT testing revealed 6.0 +/- 0.9 mm, 8.1 +/- 1.9 mm, and 8.9 +/- 1.1 mm of anterior translation after fixation in the tension groups of 68, 45, and 23 N, respectively. After 1,000 cycles, the translation increased to 7.8 +/- 1.0 mm, 10.5 +/- 1.9 mm, and 10.3 +/- 1.5 mm, respectively. CONCLUSIONS: This study showed that initial graft tension decreases with cyclic loading, resulting in increased knee laxity. To restore anterior translation to within 3 mm of the native ACL condition after cyclic loading, approximately 68 N of initial tension is required using this fixation technique.

Anterior Cruciate Ligament↗
PubMed2003

The effect of suture anchor design and orientation on suture abrasion: An in vitro study.

PURPOSE: To evaluate the effects of suture anchor design and orientation on suture abrasion in a cyclic model. TYPE OF STUDY: In vitro. METHODS: Biomechanical studies have shown suture breakage to be a predominant mode of failure in a suture anchor repair construct. It is possible that suture abrasion during knot tying or in vivo cyclic loading may contribute to early failure. This study specifically investigates suture abrasion caused by 17 commonly used suture anchors and demonstrates the effects of suture anchor angulation and rotation on suture abrasion. To eliminate target tissue as a source of failure, all anchors were implanted into a solid block of sawbones material and tested with No. 2 Ethibond Excel sutures (Ethicon, Somerville, NJ). The testing model focused on 3 variables: suture anchor type, suture pull angle (SA) and angle of anchor rotation (RA). Abrasion testing was then performed on a servohydraulic materials testing system by continually cycling the suture back and forth through each anchor with an excursion of 4 cm at a rate of 0.5 Hz under a load of 10 N until suture failure occurred. RESULTS: Sutures performed significantly better when cycled in line with the anchor at 0 degrees SA with 0 degrees RA than they did at 45 degrees SA with 0 degrees RA or 45 degrees SA with 90 degrees RA. We found no significant difference between anchors tested at 45 degrees SA with 0 degrees RA and 45 degrees SA with 90 degrees RA. For tests performed using metallic suture anchors, all constructs failed by fraying of the suture. Constructs using biopolymer anchors and nonabsorbable polymeric anchors experienced a mixture of suture and anchor eyelet failures. CONCLUSIONS: In addition to the statistically significant detrimental effects of suture anchor angulation and rotation on suture abrasion, suture anchor eyelet design may also influence suture abrasion. Surgeons should be aware of the effects of anchor angulation, suture position in the eyelet, and design and composition of the eyelet to maximize the durability of the construct.

Biopolymers↗
PubMed2002

Anatomy and biomechanics of the anterior cruciate ligament.

This article reviews the literature on embryology, anatomy, function, and biomechanics to define the properties of the native ACL. The discussion focuses on the ligamentous architecture and gross anatomy of the ACL including its femoral and tibial insertions as well as its midsubstance passing through the intercondylar fossa. Biomechanical modeling, mechanical and structural properties, and function of the ACL as a primary and secondary stabilizer under non-weightbearing and weightbearing conditions are described.

Anterior Cruciate Ligament↗
PubMedDate not supplied

A survey of the tension applied to a doubled hamstring tendon graft for reconstruction of the anterior cruciate ligament.

PURPOSE: Currently there is no consensus regarding the amount of tension to apply to a graft when reconstructing the anterior cruciate ligament (ACL). We undertook a study to determine whether sports trained orthopedic surgeons tension hamstring tendon grafts maximally during ACL reconstruction, and also whether surgeons tend to load their grafts within a narrow range of tensions. TYPE OF STUDY: Cross-sectional study. METHODS: One fresh-frozen cadaveric knee with appropriately placed femoral and tibial tunnels and five pairs of preconditioned semitendinosus and gracilis tendons were used. Custom-made computer software and a custom-made, load measurement device was employed. Thirteen orthopedic sports medicine physicians from our community took part in the study. Surgeons were asked to tension the graft as they would in surgery and were then asked to tension the graft maximally. RESULTS: The mean and standard deviation of the normal tension (14.8 +/- 7.2 lb) was significantly less (P =.005) than the mean maximal tension (22.3 +/- 6.9 lb). CONCLUSIONS: This study shows that most ACL surgeons do not tension their graft maximally. Moreover, graft tensioning is highly variable among sports medicine orthopedists. These findings revisit the question as to whether tension should be more accurately measured and controlled for intraoperatively.

Anterior Cruciate Ligament↗
PubMedDate not supplied

Glenohumeral articular contact areas and pressures following labral and osseous injury to the anteroinferior quadrant of the glenoid.

The objective of this study was to determine the effect of progressive labral and bone loss on the articular contact area and pressures across the glenohumeral joint under compressive loads of 220 and 440 N. Eight fresh-frozen cadaver shoulders were used, and contact pressures in 4 quadrants of the glenoid were determined with a Tekscan flexible tactile force sensor. Testing conditions included intact glenoids, glenoids with the anteroinferior labrum removed, and glenoids with 3 sizes of bone defects in the anteroinferior quadrant. By means of Tekscan sensing equipment, the measured contact area over the glenolabral complex was between 49.0% and 61.5% of the calculated surface area for the intact specimens. Loss of the anteroinferior labrum decreased contact area by 7% to 15% compared with the intact specimens, and the mean contact pressure increased by 8% to 20%. With bone loss corresponding to a defect measuring 30% of the diameter in the anteroinferior quadrant, contact area across the entire glenoid decreased a mean of 41% compared with the intact specimens, whereas the mean contact pressure increased nearly 100%. When the anteroinferior quadrant of the glenoid was analyzed separately, loss of the anteroinferior labrum alone resulted in an increase in the mean contact pressure in this quadrant compared with the intact specimens (mean, 53%). Bone loss of 30% of the diameter resulted in mean contact pressures in this quadrant increasing by 300% to 400% compared with the intact specimens, with 2 of 8 specimens becoming grossly unstable. In addition, with 30% diameter bone loss, the mean contact pressure decreased by 26% in the posterosuperior quadrant, indicating a shift in loading of the cadaveric glenoid. Peak pressures followed similar trends, with labral loss alone increasing peak pressures in the anteroinferior quadrant by a mean of 28% of that seen for the intact specimens.

Adult↗
PubMedDate not supplied

Treatment of postoperative anterior cruciate ligament infections with graft removal and early reimplantation.

BACKGROUND: Septic arthritis after arthroscopic anterior cruciate ligament reconstruction is rare, and the most appropriate treatment is unclear. Current recommendations are that, if the graft is removed, reimplantation should be delayed for 6 to 9 months. HYPOTHESIS: Early removal of the graft with appropriate infection management followed by early reimplantation can lead to good results. STUDY DESIGN: Uncontrolled retrospective review. METHODS: Records of all patients who developed postoperative infection after anterior cruciate ligament reconstruction were reviewed. Four patients had early graft removal and appropriate infection management including 6 weeks of intravenous antibiotics followed by anterior cruciate ligament graft reimplantation within 6 weeks of completion of antibiotic therapy. RESULTS: Follow-up at an average of 21 months (range, 14 to 31) showed that the patients treated with early reimplantation had full symmetric knee range of motion and no effusion. The average modified Lysholm score was 92.5. Radiographs demonstrated no joint-space narrowing or osteophyte formation. The 30-pound KT-1000 arthrometer side-to-side difference averaged 3 mm. CONCLUSION: Graft removal after confirmed anterior cruciate ligament graft infection and intravenous antibiotic administration followed by early graft reimplantation can give excellent results.

Adolescent↗
PubMedDate not supplied

Meniscal injury: I. Basic science and evaluation.

The patient with meniscal injury may present with pain, swelling, or mechanical symptoms and often requires surgical intervention for symptom resolution. Treatment of such injuries relies on understanding the gross and microanatomic features of the meniscus that are important in maintaining meniscal function. The ability of the meniscus to participate in load bearing, shock absorption, joint lubrication, and joint stability depends on the maintenance of its structural integrity. The diagnosis of meniscal injury often can be made by clinical evaluation utilizing the history, physical examination, and plain radiographs. Magnetic resonance imaging can be useful in confirming the diagnosis when clinical findings are inconclusive. Treatment depends on tear pattern, vascularity, and an assessment of tissue quality. Surgical decision making for the treatment of meniscal injury is based on patient factors and understanding of the meniscal structure, function, and pathology.

Humans↗