Graft Compression Research Articles

Anterior cervical dynamic ABC plating with single level corpectomy and fusion in forty-two patients.

Forty-two consecutive patients undergoing dynamic ABC plated one-level ACF utilizing iliac crest autograft (38 patients) and fibula allografts (four patients) were evaluated. The unique ABC slotted plate design allows for up to 10 mm of cephalad and 10 mm of caudad plate migration. To evaluate the incidence and etiology of complications in forty-two patients undergoing anterior cervical dynamic ABC plating (Aesculap, Tuttlingen, Germany), during one level anterior corpectomy with fusion (ACF). New York, USA. Serial dynamic X-ray and 2 Dimensional CAT Scan (2D-CT) studies, obtained 3, 6, and up to 12 months postoperatively, in 42 patients documented the presence of fusion or complications including plate or graft extrusion or pseudarthrosis. Four (9.5%) of 42 patients developed postoperative plate or graft-related complications during the average follow up interval of 34 months. One patient, with a plate/graft extrusion, required a second two level ACF with posterior wiring and fusion (PWF). Two patients with pseudarthroses and one patient with a delayed iliac crest strut fracture required secondary PWF. Effective arthrodesis and a low incidence of complications following one level ACF performed utilizing dynamic ABC plates were attributed to reduced stress shielding and greater graft compression afforded by the unique plate design. Applying dynamic ABC plates for one level ACF was biomechanically advantageous with low morbidity.

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.

Initial stability of cervical spine fixation: predictive value of a finite element model. Technical note.

The purpose of this study was to generate a validated finite element (FE) model of the human cervical spine to be used to analyze new implants. Digitized data obtained from computerized tomography scanning of a human cervical spine were used to generate a three-dimensional, anisotropic, linear C5-6 FE model by using a software package (ANSYS 5.4). Based on the intact model (FE/Intact), a second was generated by simulating an anterior cervical fusion and plate (ACFP) C5-6 model in which monocortical screws (FE/ACFP) were used. Loading of each FE model was simulated using pure moments of +/- 2.5 Nm in flexion/extension, axial left/right rotation, and left/right lateral bending. For validation of the models, their predicted C5-6 range of motion (ROM) was compared with the results of an earlier, corresponding in vitro study of six human spines, which were tested in the intact state and surgically altered at C5-6 with the same implants. The validated model was used to analyze the stabilizing effect of a new disc spacer, Cenius (Aesculap AG, Tuttlingen, Germany), as a stand-alone implant (FE/Cenius) and in combination with an anterior plate (FE/Cenius+ACFP). In addition, compression loads at the upper surface of the spacer were investigated using both models. As calculated by FE/Intact and FE/ACFP models, the ROM was within 1 standard deviation of the mean value of the corresponding in vitro measurements for each loading case. The FE/Cenius model predicted C5-6 ROM values of 5.5 degrees in flexion/extension, 3.1 degrees in axial rotation (left and right), and 2.9 degrees in lateral bending (left and right). Addition of an anterior plate resulted in a further decrease of ROM in each loading case. The FE/Cenius model predicted an increase of compression load in flexion and a decrease in extension, whereas in the FE/Cenius+ACFP model an increase of graft compression in extension and unloading of the graft in flexion were predicted. The current FE model predicted ROM values comparable with those obtained in vitro in the intact state as well as after simulation of an ACFP model. It predicted a stabilizing potential for a new cage, alone and in combination with an anterior plate system, and predicted the influence of both loading modality and additional instrumentation on the behavior of the interbody graft.

Bone graft force in anterior cervical fusions without anterior plating

Bone graft force in anterior cervical fusions without anterior plating

Myocardial infarction due to saphenous vein graft compression by an extracardiac mass

We present an unusual case of a patient with an inferior infarct caused by saphenous vein graft compression by an extracardiac malignant spindle cell tumour, a mechanism of myocardial ischaemia rarely described. This case also illustrates how chest X-ray and angiography can be useful for making an early diagnosis of a cardiac mass.

Laser hair transplantation II.

Micrografting has revolutionized hair transplantation, resulting in far more natural results than have been achieved prior to this technique. Operative problems including bleeding, graft compression, and ease of graft insertion have been alleged to be decreased with the use of a high-energy pulsed CO2 laser for creation of recipient sites. However, because of thermal injury to surrounding tissue, diminished hair growth and slower wound healing also have been seen. A new laser handpiece, designed to minimize tissue thermal damage to hair recipient sites was tested in comparison to 18-gauge needle recipient sites in the same patients. Hair growth counts at 6 months as well as various measurements of operative problems were compared. Two hundred laser grafts were performed on one scalp side and compared to 200 needle grafts on the opposite side. Hair counts preoperatively and at 6 months were performed. Biopsies for depth and surrounding tissue damage were taken intraoperatively. Time for completion of various stages of the procedure for each side were recorded, as well as the incidence of side effects per side. Hair growth was equal for each side. Bleeding and operative time were significantly reduced and ease of graft insertion was increased on the laser side. Graft compression and scarring were not seen. Laser hair transplantation is faster than using conventional techniques and results in equal hair growth, and should be considered as a viable alternative technique.

Experience with laser hair transplantation in Orientals.

The advent of high-energy carbon dioxide (CO2) laser-assisted hair transplantation in recent years provides a new recipient area technique for hair restoration surgery. It offers the advantages of less bleeding, time consumption, and graft compression. Specific laser parameters have been recommended in Caucasian but not Oriental patients. To determine the effectiveness as well as appropriate parameters of laser hair transplantation in Oriental patients. A Sharplan SilkTouch laser with the Flashscanner set to produce a 0.8-1-mm recipient site hole was employed for all subjects. Various CO2 laser parameters were used to compare the graft survival rate with traditional Nokor needle or microdilator methods for micrografting on each side of the scalp. A total of 20 patients joined the study in the past 18 months. A skin biopsy was performed to examine the tissue effect of the different laser parameters. Hair survival was less than that seen with conventional micrografting techniques in the first five cases, in whom CO2 laser parameters of 36-40 W and 0.2-0.7 seconds were used. After adjusting the parameters to 55 W and 0.1-0.15 seconds, the survival rate increased to between 80% and 90%. In addition, most patients thought the laser-prepared sites resulted in a more natural appearance and better hair density, when they were compared with conventionally prepared sites. From our study, we find that CO2 laser parameters of 55 W and 0.1-0.15 seconds seem to be the appropriate parameters for Oriental hair transplant patients. Further studies are required to establish laser parameters that will produce better hair survival.

Does hyperexpansion of the native lung adversely affect outcome after single lung transplantation for emphysema? Preliminary findings

The authors evaluated the effect of the native emphysematous lung on graft function after single lung transplantation. Thirty-two patients who underwent single lung transplantation were examined with radiography preoperatively for degree of emphysema and postoperatively for hyperexpansion of the native lung. All patients underwent ventilation-perfusion scanning before transplantation and ventilation scanning after transplantation. Pulmonary function tests and measurement of arterial partial pressure of oxygen were also measured before and after surgery. The postoperative course was graded on a subjective scale. Hyperexpansion of the native lung was seen in 16 of the 32 patients in the postoperative period. On the basis of serial measurements of forced expiratory volume in 1 minute, these patients fared poorly in the postoperative period compared with patients without hyperexpansion. Pulmonary blood flow to the native lung, as measured with perfusion scintigraphy, paradoxically increased in 11 patients after transplantation. Nine of these 11 patients demonstrated hyperinflation of the native lung, suggesting that graft compression adversely affects blood flow to the transplanted lung. Hyperexpansion of the native lung after single lung transplantation for emphysema may have a deleterious effect on graft function and possibly on clinical outcome.

Rhomboid minigrafts in hair restoration surgery.

The transplantation of large numbers of three- to five-hair minigrafts has superseded the use of traditional punch grafts in hair restoration surgery. The minigrafts are usually designed and cut in a square or rectangular shape for implantation into the recipient slits. Transplanting a large number of these grafts into the recipient slits can lead to a high frequency of complications, especially in cases in which there is a need for dense packing of grafts. The complications include excess graft compression resulting in extrusion or retraction into the slit. This in turn can lead to piggybacking or insertion of two grafts per slit with the resultant effect of cyst formation, cobblestoning, and hypertrophic scar formation. To develop an optimal shape of minigrafts to match the recipient slits. The authors have calculated the optimum geometric configuration for a minigraft in a linear slit and have developed the correct cutting instrument and preparation technique for its production. This rhomboid minigraft design maximizes the graft stability in the slit and therefore its survival, and also minimizes the risk of complications. The described technique shows that the transplanted rhomboid minigrafts remain well anchored in the recipient slits and results in an excellent clinical outcome. The rhomboid minigrafting technique (1.5 x 1.5 mm in size) seems to accommodate the grafts better into the recipient slits than the standard shape rectangular minigrafts. It thereby better facilitates the insertion of the grafts in the slits and reduces the frequency of graft extrusion as well as graft compression.

Optimal Selection and Preparation of Fresh Frozen Corticocancellous Allografts for Anterior Interbody Lumbar Spinal Fusion

To determine the effect of graft preparation on graft strength, corticocancellous grafts suitable for anterior interbody fusion were obtained from six cadavers using five different donor bone sites with different graft sectioning orientations and locations. Graft compression strength was determined in simulated physiological loading. The distal tibia and femoral head lumbar interbody grafts are significantly stronger than grafts prepared from other corticocancellous donor sites. Graft fabrication by cutting perpendicular to the long axis and closer to the long bone ends results in increased graft strength.

“Legs” technique for management of widely separated coronary arteries during ascending aortic repair

Widely separated coronary arteries with significantly diseased tissue continues to challenge surgeons repairing ascending aortic aneurysms. Occasional troublesome leaks around coronary ostial anastomoses and Cabrol graft thrombosis prompted a change of our operative management of this condition. Collagen-impregnated 8-mm "legs" grafts are used to connect the coronary arteries to the composite graft. Ten patients, aged 14 to 70 years, underwent the operation. The first patient is 15 years after the operation and is symptom free. One patient died of an arrhythmia 1 month after discharge. Eight patients are living and well 11/2 to 4 years postoperatively. Advantages of direct interposition (legs) grafts are as follows: the coronary arteries are separately perfused and the risk of catastrophic thrombosis from a longer high-volume graft is eliminated. Problems with coronary ostial mobilization are avoided. The technique allows full visualization and hemostatic suture line testing with cardioplegia before aortic declamping. Space constraints with reoperations are easily managed, whereas other techniques may result in graft compression on refilling of the heart and termination of bypass. The technique is carried out with ease and reproducibility, and the availability of new graft material has made it our treatment of choice for ascending aortic composite graft replacement.

Single lung transplantation for end stage emphysema.

The first successful single lung transplantation was carried out in 1983 for pulmonary fibrosis. Because of the inherent advantages of single lung transplantation, a transplantation programme has been started for patients with end stage lung disease due to emphysema. Between October 1990 and August 1993 25 patients with severe emphysema (15 men, mean age 51 years) received a single lung transplant at our institution. All patients were severely disabled with a mean (SD) 12 minute walking distance of 281 (165) metres. There were five deaths in the series, four in the first 20 days and one on day 503. Two patients suffered graft compression by air trapping in the native lung. Bronchial narrowing requiring insertion of endobronchial stenting occurred in four patients. Mean (SD) FEV1 improved from a preoperative value of 17.8(13%) predicted to a six month value of 53.6(13)%, and FEV1/FVC from 23.8(12)% to 68.6(15)%. After the transplant 12 patients are in New York Heart Association (NYHA) class I and the rest of the survivors are in NYHA II. Actuarial survival was 82% at one year and 74% at three years. Single lung transplantation is an effective treatment for end stage lung disease due to emphysema and carries an acceptable mortality and morbidity.

The Mercedes Incision in Hair Restoration

Standard technique for hair transplantation includes plug composite grafts placed in circular recipient defects of smaller diameter. The plugs can also be placed in slit incisions that are temporarily dilated to accommodate grafts. Two drawbacks of these techniques are the appearance of row cropping resulting from the regular pattern and compression of individual grafts caused by scar contracture. These drawbacks result in tufting and a "doll's head" appearance. The expansile Mercedes incision as described here camouflages these failings. Donor minigrafts are taken with a biopsy punch knife or as strips in a standard fashion. A Mercedes logo-shaped defect is then made at the recipient site using a no. 11 scalpel to create a three-armed stellate incision. The incisions are rapidly made with the axis oriented parallel to the direction of the native hair shafts. The graft is then pushed in flush with the skin. The triangulation eliminates compression of grafts because they are spread in three directions rather than squeezing in a tight circular or slit configuration. The use of the stellate incision along with altering its rotational orientation in a haphazard pattern also prevents row cropping. Thus, the Mercedes incision is quicker and yields an overall improved result.

ＲＡの頚椎病変に対する手術的治療の検討

The results of surgical treatment performed on the cervical spine of 12 patients with rheumatoid arthritis were evaluated.The mean age at the time of operation was 56.4 years (range; 44-63 years) and the mean duration of the disease was 18 years (range; 5-38). They were followed-up for a mean of 3 years 5 months (range; 4 months-6 years 6 months). llpatients achieved relief of their occipitocervical pain, and paralysis improved in seven.In two patients with atlanto-axial subluxation (AAS) and vertical subluxation (VS), cranio-cervical stabilization was performed producing good. Anterior fusion was performed in five patients with subaxial subluxation (SS), but graft compression or subluxation above or below the fused segments occurred in four patients, and two patients required further surgery. Cranio-cervical stabilization for SS, AAS, VS was performed in five patients and the results obtained were good.We regard cranio-cervical stabilization using instrumentation as useful in the treat ment of cervical spinal problems in Rheumatoid Arthritis patients.

Hair transplantation facilitated by flashscanner-enhanced carbon dioxide laser

One of the complications of hair transplantation is bleeding when the recipient sites are created in the vertex and frontal portions of the scalp. The bleeding, although rarely a problem from a hemodynamic standpoint, leads to prolonged surgical time, trauma to grafts from multiple handlings, and loss of grafts. The grafts will often pop up, and with any degree of hemorrhage, ooze out because they are not sutured in place, especially when using micrograft and minigraft techniques. Another phenomenon that can occur is graft compression. When a recipient hole or slit is created, the tissue compresses the graft, leading to presumed hypoxia and decreased hair growth. However, when tissue is vaporized with a laser, appropriate room is created for the graft to rest in its place, thus avoiding graft compression. The use of lasers in hair transplantation is only recent and the challenge in its use for this purpose is to create a cylindrical bloodless recipient site (for both micrografts and minigrafts) and at the same time to allow full graft take by minimizing the zone of thermal necrosis. This report describes full graft take following creation of the recipient sites using a Silktouch (Model 765; Sharplan Lasers Inc, Allendale, NJ) flashscanner-enhanced carbon dioxide (CO2) laser. optical density of above 300 W/mm 2 on tissue. This is considerably higher than the threshold for vaporization of tissue without residual carbon char (the threshold for char-free tissue ablation is about 50 W/mm2). 3 The time required for the Silktouch to homogeneously cover a 2-mm round area is 200 milliseconds. During this time, a 10-W operating laser will deliver 2,000 mJ to the tissue. Because the typical energy required to ablate tissue completely is about 3,000 mJ/mm 2, keeping the handpiece precisely on a single site for 1.0 seconds will generate a clean, almost char-free crater of approximately 2.5 mm in depth. A healthy 50-year-old white male with moderately advanced male-pattern baldness (Hamilton grade II, Abbott Laboratories, North Chicago, IL) volunteered for test sites. After local infiltration anesthesia with Xylocaine without epinephrine, five minigraft recipient sites were created on the vertex of the scalp, each 2 mm in diameter and 6 mm in depth, using the Silktouch-enhanced CO 2 laser. The depth of the cylindrical hole was verified using a measuring probe. The CO 2 laser was used twice in the same spot for 1.0 seconds at a power setting of 15 W. Grafts obtained from a 1.5 cm-long strip graft from the occipital scalp were cut to size and placed in the recipient holes using standard techniques. No bleeding was ob

Urinary protein/creatinine index in follow up of patients with Wilms' tumour after nephrectomy.

The protein/creatinine index (p/c) was determined in early morning urine (EMU) samples from available patients with Wilms' tumour who had had a nephrectomy and whose diagnosis had been made between January 1970 and December 1989. Clinical details were obtained by case note review. Results were obtained from 36 boys and 40 girls. The mean interval between nephrectomy and measurement of the EMUp/c was 9.0 years (2-23). Eleven patients had a EMUp/c greater than 20 mg/mmol (normal range less than 20). Of the 11 patients with proteinuria, there were in addition to nephrectomy other adverse features including bilateral tumours, treatment with nephrotoxic drugs, and dysplastic kidneys. Renal dysfunction seems most likely to occur where there are adverse factors in addition to unilateral nephrectomy. There was a significant correlation between the glomerular filtration rate and the EMUp/c, and it is thought that this is a simple tool which can be used for the regular monitoring of renal function in these patients.

INLAY SPLIT SKIN GRAFTS: A SIMPLIFIED TECHNIQUE

A simplified technique for the fixation and compression of inlay split skin grafts is described.

The Postoperative Spine: Magnetic Resonance Imaging

MRI is rapidly becoming the imaging modality of choice in the diagnostic assessment of patients with persistent or recurrent symptoms following spinal surgery. It displays the normal postoperative findings as well as most causes of FBSS. MRI can differentiate persistent or recurrent disk herniation from postoperative scar formation with a greater degree of confidence than other imaging modalities. MRI can determine clinically important functional instability when CT and conventional radiography are inconclusive. This can be particularly helpful in evaluating the patient with multiple lumbar surgeries. MRI can also determine the presence of other causes of the FBSS such as lateral spinal stenosis, arachnoiditis, fat graft compression on the thecal sac, and presence of postoperative hematoma or postoperative infection.

Nonreversed and in situ vein grafts. Clinical and experimental observations.

The in situ saphenous vein (ISSV) graft has shown promise in distal bypass. Although improved patency has been attributed to preservation of vasa vasorum, there is no direct evidence to support this hypothesis. Femorodistal bypass was done in 33 patients using ISSV grafts (21) or nonreversed saphenous vein (NRSV) grafts (12) during an 18-month period. The NRSV were completely removed from the vein bed but were otherwise prepared in an identical fashion to the ISSV. Immediate complications including incomplete valvulotomy (one), intimal laceration (one), persistent AV communication (two), and extrinsic graft compression (one) were identified and corrected. Two grafts of 2.5 mm diameter occluded acutely. There were no deaths. Of 30 patients discharged with a patent graft, there was one late occlusion (ISSV) at 10 months. No difference in patency between ISSV and NRSV grafts was noted during follow-up extending to 24 months. Overall limb salvage was 94%. In a canine model, 60 vein segments were interposed in the carotid artery using in situ, reversed, and nonreversed techniques. Ultrastructural studies 1, 2, 3, and 6 months after implantation reveal no differences in in situ and nonreversed grafts. New vasa vasorum were identified in NRSV within 1 month. Both ISSV and NRSV grafts demonstrate excellent patency and maintenance of smooth muscle cell architecture. Factors including reduced size disparity at the proximal and distal anastomoses, physiologic distension under arterial pressure, careful handling, and meticulous technique appear to be more important than the theoretic advantages of preserving vasa vasorum.

Effect of external pressure on axillofemoral bypass grafts.

External compression of axillofemoral grafts has been suggested many times as a cause for graft thrombosis. Thrombosis during sleep is the most common presentation of axillofemoral graft failure. Therefore, external compression of the graft by the body weight has been implicated in graft thrombosis. Six consecutive patients with axillofemoral bypass grafts for aortoiliac disease were studied on routine clinic visits. Pulsatile flow characteristics were studied by pulse volume recordings (PVR) and segmental Doppler pressure measurements in calf and ankle, prior to and during attempted graft compression, by having the patient lay on the graft. External compression by body weight did not alter the PVR and segmental Doppler pressure (P = NS) in the distal circulation. Therefore, these data suggest that external compression by the body weight may not be the primary cause of graft failure.