Effect Of Graft Size Research Articles

The effects of graft size and insertion site location during anterior cruciate ligament reconstruction on intercondylar notch impingement

BackgroundIntercondylar notch impingement is detrimental to the anterior cruciate ligament (ACL). Notchplasty is a preventative remodeling procedure performed on the intercondylar notch during ACL reconstruction (ACLR). This study investigates how ACL graft geometry and both tibial and femoral insertion site location may affect ACL-intercondylar notch interactions post ACLR. A range of ACL graft sizes are reported during ACLR, from six millimeters to 11mm in diameter. Variability of three millimeters in ACL insertion site location is reported during ACLR. This study aims to determine the post-operative effects of minor variations in graft size and insertion location on intercondylar notch impingement. MethodsSeveral 3D finite element knee joint models were constructed using three ACL graft sizes and polar arrays of tibial and femoral insertion locations. Each model was subjected to flexion, tibial external rotation, and valgus motion. Impingement force and contact area between the ACL and intercondylar notch compared well with experimental cadaver data from literature. ResultsA three millimeter anterior–lateral tibial insertion site shift of the maximum size ACL increased impingement force by 242.9%. A three millimeter anterior–proximal femoral insertion site shift of the maximum size ACL increased impingement by 346.2%. Simulated notchplasty of five millimeters eliminated all impingement for the simulation with the greatest impingement. For the kinematics applied, small differences in graft size and insertion site location led to large increases in impingement force and contact area. ConclusionsMinor surgical variations may increase ACL impingement. The results indicate that notchplasty reduces impingement during ACLR. Notchplasty may help to improve ACLR success rates.

Effects of Disc Height and Distractive Forces on Graft Compression in an Anterior Cervical Corpectomy Model

An in vitro biomechanical study using a calibrated distractor and a subminiature load cell in a cadaveric cervical corpectomy construct. To study the inter-relationships of defect height, graft height, and compressive and distractive forces in an anterior cervical corpectomy model. The effects of graft size on compressive and distractive forces in cervical corpectomy remain unknown. Larger grafts afford neural decompression through anterior column distraction, but may subject the graft and vertebral bodies to excessive loads, increasing graft fracture, and subsidence risk. The intended corpectomy defect was measured radiographically in 17 specimens. A C6 corpectomy was performed and the specimens embedded in polyester resin. A distractive force was applied through a strain gauge fitted distractor to allow introduction of allograft struts fixed to a subminiature load cell. After distraction was removed, immediate compressive force was measured. The specimen was then placed in a loading frame to simulate head weight. Distractive forces of 36.65, 70.90, and 118.10 N were required to insert 23, 25, and 27 mm grafts, respectively. On removal of this distraction, immediate compressive loads of 2.87, 4.74, and 8.95 N were noted. No statistically significant relationship between the intended corpectomy height and graft distraction forces was found. A statistically significant relationship was observed between distractive force required for graft insertion and immediate graft compressive force. Distractive force was also significantly related to the compressive force borne by the loaded strut graft. Significantly higher distractive and compressive forces were recorded with larger grafts. Intended corpectomy height was not an accurate predictor of graft loads.

Effect of Graft Size, Angle, and Intergraft Distance on Dense Packing in Hair Transplant

The maximum number of hair grafts that can be safely implanted in 1 cm2 is still debatable. To our knowledge, no previous report has addressed this issue in three dimensions, taking into account the size, the angle of the graft, and the intergraft distance. To study the effect of the size and angle of the graft and the intergraft distance on dense packing. Using a mathematical formula (the maximum number of hair grafts in 1 cm2 = 33 * cosine), the volume of the recipient area and the volume of the hair graft are calculated, assuming that the surface area of the recipient area is 1 cm2, the diameter of the hair graft is 1 mm, and the intergraft distance is 1.5 mm laterally and 1 mm anteriorly and posteriorly. The maximum number of hair grafts that could be implanted in 1 cm2 at a 90 angle in relation to the skin surface is 33 grafts, at a 60 angle is 28 grafts, and at a 30 angle is 16 grafts. The maximum number of hair grafts that can be implanted in any given recipient area depends on the graft size, the angle or direction of these grafts, and the intergraft distance. Where more space is allowed between the grafts, and the more acute the angle, the fewer hair grafts that can be implanted.

Effect of Graft Size, Angle, and Intergraft Distance on Dense Packing in Hair Transplant

Effect of Graft Size, Angle, and Intergraft Distance on Dense Packing in Hair Transplant

Effects of disc height and distractive forces on graft compression in an anterior cervical discectomy model.

An in vitro biomechanical study using a calibrated distractor and a subminiature load cell in a cadaver anterior cervical discectomy construct was conducted. To study the interrelations of preoperative disc height, graft height, and compressive and distractive forces in an anterior cervical discectomy model. The effects of graft size on compressive and distractive forces in a discectomy model remain unknown. Larger grafts afford neural decompression through anterior column distraction. This distraction may subject the graft and vertebral bodies to excessive loads, increasing graft fracture, and subsidence risk. Disc height was measured radiographically in 18 specimens. A Smith-Robinson discectomy was performed, and the superior and inferior ends of the specimens were embedded in polyester resin. Distraction was applied through a calibrated Caspar distractor to measure the distractive force applied while steel spacers rigidly fixed to a subminiature load cell were introduced. After distraction was removed, immediate compressive force was measured. Distractive forces of 112.4 N and 189.9 N were required to insert the 6-mm and 8-mm grafts, respectively. When this distractive force was removed, immediate compressive loads of 8.8 N and 21.5 N on the graft were noted. When a compressive load of 45 N was applied in a loading frame, measured graft loads of 16.2 N and 29.2 N also increased. No statistically significant relation was observed between preoperative disc height and distractive force or compression of the graft. Significantly lower distractive and compressive forces were associated with insertion of the 6-mm rather than 8-mm graft. Significantly higher distractive and compressive forces were recorded with larger grafts. Preoperative disc height was not an accurate predictor of graft loads.

Bone marrow reconstitution after high-dose chemotherapy and autologous peripheral blood progenitor cell transplantation: Effect of graft size

Peripheral blood progenitor cell transplantation is rapidly replacing autologous bone marrow transplantation as hematological support after high-dose chemotherapy for lymphoma or solid tumors. Controversy exists concerning the number of progenitor cells required for rapid and sustained bone marrow recovery, and as to which of the widely available methods for estimating this number should be employed. Forty consecutive patients with solid tumors or lymphomas received high-dose chemotherapy followed by autologous peripheral stem cell reinfusion. All stem cell harvests had been performed after mobilization with standard-dose chemotherapy followed by 300 micrograms G-CSF daily. Hematopoietic reconstitution was studied in relation to pertinent patient characteristics, to the size of the graft (in terms of the total number of mononuclear cells (MNC), the number of granulocyte/macrophage colony-forming units (CFU-GM) and the number of CD34+ cells, and to the use of G-CSF after stem cell reinfusion. Both the numbers of CFU-GM and CD34+ cells reinfused, but not those of the MNC, correlated with granulocyte and platelet recovery. Patients who received at least 5 x 10(6) CD34+ cells/kg body weight achieved platelet transfusion independence on day 12 after reinfusion (range: day 7-37), significantly earlier than patients who had received less (p = 0.001). Thirty patients who received G-CSF (300 micrograms s.c. daily) after reinfusion achieved granulocyte recovery (> or = 500 x 10(6)/l) on day 9 (range: day 8-12), while this took a median of 15 days (range: day 10-28) in 10 consecutive patients not receiving G-CSF (p = 0.0003). In one patient who had received 1.4 x 10(6) CD34+ cells/kg, secondary bone marrow failure developed 3 months after transplantation. Reinfusion of cryopreserved autologous bone marrow was followed by prompt recovery. Peripheral stem cells, mobilized by moderate-dose chemotherapy and G-CSF, lead to rapid and durable engraftment after high-dose chemotherapy when at least 3-5 x 10(6) CD34+ cells/kg are reinfused. Lower numbers may also be satisfactory, but are associated with slower granulocyte and platelet recoveries. A moderate dose of G-CSF after reinfusion significantly hastens granulocyte recovery without interfering with platelet recovery.