Distal Pedicle Research Articles

Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis Following Segmental Posterior Spinal Instrumentation and Fusion

A retrospective study. To analyze the long-term proximal junctional change in adolescent idiopathic scoliosis (AIS) following segmental posterior spinal instrumentation and fusion 5 years or more after surgery. No study has concentrated on time-dependent long-term proximal junctional change in AIS following segmental posterior spinal instrumentation and fusion after 5 years postoperation. Risk factors for developing proximal junctional kyphosis (PJK) are unknown. A total of 193 consecutive AIS patients with a minimum 5-year follow-up (average, 7.3 years; range, 5-16.7 years) treated with segmental posterior spinal instrumentation and fusion were evaluated. Radiographic measurements analyzed included sagittal Cobb angle at the proximal junction on preoperative, early postoperation, 2-year postoperation, and final follow-up (> or = 5 years) by standing long cassette radiographs. Postoperative Scoliosis Research Society (SRS)-24 outcome scores were also evaluated. Abnormal PJK was defined as the final proximal junctional sagittal Cobb angle between the lower endplate of the uppermost instrumented vertebra and the upper endplate of two vertebrae supra-adjacent, which was > 10 degrees and at least 10 degrees greater than the preoperative measurement. The incidence of PJK at 7.3 years postoperation was 26% (50 of 193 patients). The average proximal junctional angle increased 15.2 degrees until 2 years postoperation and then increased 1.7 degrees until final follow-up in the PJK group (n = 50). Factors that were statistically significant for PJK development were as follows: a thoracoplasty procedure (P = 0.001), preoperative hyperkyphotic thoracic alignment (T5-T12 > 40 degrees) (P = 0.015), and hybrid instrumentation (proximal hooks and distal pedicle screws) compared with the hooks only group (P = 0.029). The number of fused vertebrae more than 11 was also related with PJK (P = 0.08). The level of the uppermost instrumented vertebra did not affect the PJK incidence. SRS-24 outcome scores did not demonstrate any significant differences (P = 0.54 for total score and P = 0.49 for self-image subscale) between the PJK and non-PJK groups. The incidence of proximal junctional kyphosis at 7.3 years postoperation was 26% and did not progress significantly after 2 years postoperation. Risk factors for developing PJK were an associated thoracoplasty, hybrid instrumentation (proximal hooks and distal pedicle screws), and a preoperative larger sagittal thoracic Cobb angle (T5-T12 > 40 degrees). The SRS-24 outcome instrument was not affected by PJK.

Thoracic Adolescent Idiopathic Scoliosis Curves Between 70° and 100°

A retrospective review of adolescents with main thoracic scoliotic curves surgically treated with either anterior release and posterior fusion or posterior fusion only. To compare the radiographic and clinical outcomes of two surgical treatments: anterior-posterior spinal fusion (APSF) versus posterior spinal fusion (PSF) alone in patients with large 70 degrees to 100 degrees thoracic adolescent idiopathic scoliosis (AIS) curves. Surgical treatment of thoracic AIS curves between 70 degrees and 100 degrees often consists of anterior and posterior fusion to improve the coronal correction and fusion rate, with the anterior release and fusion performed through either an open thoracotomy or by video-assisted thoracoscopy. All patients (n = 84) with main thoracic major AIS curves between 70 degrees and 100 degrees who underwent spinal fusion (APSF or PSF) at one center between 1987 and 2001 were included for analysis. The minimum follow-up was 2 years after surgery (mean, 4.5 years; range, 2.0-10.2 years). The mean age of patients was 13.8 years (range, 10.7-18.2 years), with 66 females and 18 males. Multiple radiographic measures were assessed. The primary and secondary statistical analyses performed were nonparametric analyses, using the Wilcoxon-Mann-Whitney tests for the primary analysis of APSF and PSF groups. The PSF subgroup analysis was performed with the Kruskal-Wallis test. There were 22 patients in the APSF (open ASF in 18, and video-assisted thoracoscopy in 4) group and 62 patients in the PSF group. There were no statistically significant differences between the groups for gender, age, number of levels fused, Cobb measurement of preoperative coronal or sagittal thoracic curve magnitude, or coronal curve flexibility. The APSF group, when compared with the PSF group, had greater intraoperative correction of the coronal curve (48.3 degrees vs. 38.7 degrees, P = 0.0087) as well as final overall correction (47.2 degrees vs. 34.2 degrees, P = 0.0008). There were no significant differences seen in the sagittal alignment from T5-T12 (P = 0.3150) or the SRS outcomes data between the APSF and PSF only groups. Subanalysis of the PSF only group identified three distinct groups based on implants: hook-only constructs (n = 36), hybrid constructs of proximal hooks and distal pedicle screws (n = 15), and pedicle screw-only constructs (n = 11). Pedicle screw-only constructs corrected the coronal Cobb measurements more than the other two groups (47.5 degrees vs. hooks 37.7 degrees vs. hybrid 34.4 degrees , P = 0.0110), and to a similar extent as to the APSF group with no statistically significant difference in coronal correction (PSF, 47.5 degrees; APSF 48.3 degrees; P = 0.9014), nor any other parameter except for sagittal T5-T12 changes. There were no reoperations for implant failure/pseudarthroses in any of the patients. APSF of large thoracic curves allows greater coronal correction of thoracic curves between 70 degrees and 100 degrees, when compared with PSF alone using thoracic hook constructs, but not with the use of thoracic pedicle screw constructs. Scoliosis surgeons not using pedicle screw constructs need to decide if the modest improvement in coronal correction with a combined approach justifies its routine use in this patient population.

La plastie d'expansion en Oméga « Ω » : une nouvelle technique de traitement chirurgical de la ténosynovite de De Quervain

The Omega "Ω" pulley plasty: a new technique for the surgical management of the De Quervain's disease. The De Quervain tenosynovitis is an inadequacy into the first extensor compartment between the osteo-fibrous tunnel and the tendons. This mechanical conflict generates a tenosynovitis of the extensor pollicis brevis and the abductor pollicis longus tendons. This is generally expressed by a tenderness on the radial side of the wrist over the radial styloid process. The medical management consists on corticoids infiltrations of the first extensor compartment, the avoidance of repetitive and stress movements of the first ray with the use of a rest splint. The surgical approach is considered with the recurrence of the painful symptoms. This well-known pathology is reputated to require a simple section of the pulley. Our post-operative complications have been reported in the literature of this classical surgical solution. These complications concern an incomplete release of the extensor pollicis brevis and the abductor pollicis longus tendons particularly when an extensor sub-compartment exists and was overlooked, an irritation of the collateral branches of the sensitive radial nerve or the occurrence of a nevroma after a nerve injury and the most serious complication is a palmar subluxation of the extensor tendons which can occur with the thumb extended and the wrist flexed. In rare cases, this subluxation can be really painful and requires a surgical management with secondary reconstruction of the pulley. This reconstruction necessitates distal pedicle flaps from the dorsal retinaculum or the brachioradialis tendon. To prevent these complications, Codega and Kapandji described techniques of reconstruction of the pulley after its release. More recently, Le Viet reported a procedure using the anterior flap of the pulley; fixed to the dermis it will work as a barrier and maintain the tendons sliding on the radial styloid groove. These techniques require to divide the pulley and to reconstruct it suturing the different flaps. It can generate adherences between the extensor tendons, the overlying skin and the collateral branches of the radial nerve. The authors present a new and original plasty procedure of the first extensor compartment pulley, the "Ω" Omega plasty. It consists to liberate the anterior attachment of the pulley over the anterior lip of the styloïd process respecting its continuity with the periosteum flap. This conservative procedure is very interesting; it permits enough expansion of the tunnel volume decompressing the extensor tendons as a treatment of the De Quervain disease and respecting the anatomy and the continuity of the osteo-fibrous tunnel. This technique is simple, reliable and respects the first ray extensor tendons gliding physiology and biodynamic. In spite of our short clinical experience with only ten cases, all the patients retrieve a normal function of the thumb with complete disappearance of the first ray tenderness and pain without any complications. These preliminary results are encouraging and push us to consider the "Ω" plasty as a first choice for the surgical treatment of the De Quervain tenosynovitis.

The Distally Pedicled Peroneus Brevis Muscle Flap Anatomic Studies and Clinical Applications

Defects in the distal third of the lower leg with bone or tendon exposure may require local or free flap reconstruction. For small and moderate lesions, the distally pedicled peroneus brevis muscle flap may be an effective procedure with less morbidity than a free tissue transfer. Six cadaveric specimens were dissected to determine the location of distal pedicles and the flap type. This flap was found to be a Type IV flap, and the location of distal pedicle was always located within 6 cm from the fibula tip. This flap was performed on 6 patients to cover defects in the distal third of the lower leg. The defect areas were the pretibial region in 2 cases, the lateral malleolus in 3 cases, and the Achilles tendon in 1 case. The peroneus brevis muscle was detached from the uppermost point of the fibula to obtain enough length to cover the defect. All flaps survived except 1 that experienced distal flap necrosis. Minor complications included skin graft failure in 2 cases. However, the final results demonstrated a smooth contour that eliminated dead space. Limited donor site morbidity was obtained in all cases. The distally peroneus brevis muscle flap therefore offers an alternative for reconstructive surgeons dealing with soft tissue defects of the lower leg.

Histological examination of antler regeneration in red deer (Cervus elaphus)

Annual antler renewal presents the only case of epimorphic regeneration (de novo formation of a lost appendage distal to the level of amputation) in mammals. Epimorphic regeneration is also referred to as a blastema-based process, as blastema formation at an initial stage is the prerequisite for this type of regeneration. Therefore, antler regeneration has been claimed to take place through initial blastema formation. However, this claim has never been confirmed experimentally. The present study set out to describe systematically the progression of antler regeneration in order to make a direct histological comparison with blastema formation. The results showed that wound healing over a pedicle stump was achieved by ingrowth of full-thickness pedicle skin and resulted in formation of a scar. The growth centers for the antler main beam and brow tine were formed independently at the posterior and anterior corners of the pedicle stump, respectively. The hyperplastic perichondrium surmounting each growth center was directly formed in situ by a single type of tissue: the thickening distal pedicle periosteum, which is the derivative of initial antlerogenic periosteum. Therefore, the cells residing in the pedicle periosteum can be called antler stem cells. Antler stem cells formed each growth center by initially forming bone through intramembranous ossification, then osseocartilage through transitional ossification, and finally cartilage through endochondral ossification. There was an overlap between the establishment of antler growth centers and the completion of wound healing over the pedicle stump. Overall, our results demonstrate that antler regeneration is achieved through general wound healing- and stem cell-based process, rather than through initial blastema formation. Pedicle periosteal cells directly give rise to antlers. Histogenesis of antler regeneration may recapitulate the process of initial antler generation.

P77. Comparative analysis of pedicle screw versus hybrid instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis: a match cohort analysis

BACKGROUND CONTEXT: The comparative results of the posterior correction and fusion with segmental hybrid (proximal hook and distal pedicle screw) instrumentation versus those with pedicle screw constructs alone in adolescent idiopathic scoliosis (AIS) is unknown.

Sural flap vascularization in arteritic patients: an anatomic study of 24 amputation specimens.

Obliterating arteriopathy of the lower limbs is a classic contraindication for neurocutaneous islands flaps, particularly the sural flap. But recent literature reports examples of its successful application in arteritic patients. The aim of this work was to study the vascular anatomy of the sural flap in patients suffering from arteriopathy and its possible clinical application. Twenty-four specimens of leg amputation were studied. The mean age of the amputated patients was 68.5 years. The clinical signs of arteriopathy had been present for 3-16 years. In 10 cases amputation was carried out directly, in 14 cases after failed revascularization. The results of the dissection showed the theoretical possibility of a sural flap in almost all the cases (23 of 24) despite certain anatomical peculiarities. In the upper part of the leg the arterial network of the sural communicating nerve dominates that of the sural nerve; this should allow the use of a sural flap centered on this vascular axis. In the lower part, the arterial network of the sural communicating nerve is sustained by the perforators of the peroneal artery, then by the branches of the calcaneal artery, and finally by the lateral tarsal artery, which should allow the use of a sural flap with a very distal pedicle. The authors propose a theory which suggests that the progressive evolution of arteriopathy and the concomitant development of a supply network involving the vascularization of the sensory nerves induces the "anticipation" of a sural flap.

Histological studies of bone formation during pedicle restoration and early antler regeneration in roe deer and fallow deer.

The purpose of the present study was to examine the process of bone formation in the regenerating cranial appendages of roe deer (Capreolus capreolus) and fallow deer (Dama dama) during the early postcasting period. After the antlers are cast, osteoclastic and osteoblastic activities lead to a smoothing of the pedicle's separation surface, a strengthening of the pedicle bone, and a partial restoration of the distal pedicle portion that was lost along with the cast antler. Initially, bone formation occurs by intramembranous ossification, but early during the regeneration process cartilage is formed at the tips of the cranial appendages, and is subsequently replaced by bone in a process of endochodral ossification. Shortly after the antlers are cast, the cambium layer of the periosteum in the distal pedicle is markedly enlarged, which suggests that the periosteum serves as a cell source for the bone-forming tissue covering the exposed pedicle bone. The histological findings of our study are consistent with the view that the bony component of the regenerating cranial appendages of deer is largely derived from the pedicle periosteum. Based on findings in other bone systems, we speculate that stem cells that can undergo both osteogenic and chondrogenic differentiation are present in the pedicle periosteum. The early onset of chondrogenesis in the regeneration process is regarded as an adaptation to the necessity of producing a huge volume of bone within a short period. This parallels the situation in other cases of chondrogenesis in membrane bones.

Coverage of difficult wounds around the knee joint with prefabricated, distally based sartorius muscle flaps.

The coverage of soft-tissue defects around the knee joint presents a difficult challenge to the reconstructive surgeon. Various reconstructive choices are available depending on the location, size, and depth of the defect relative to the knee joint. However, the knee joint frequently accompanies injuries to the lower leg that may limit the use of muscle flaps, especially the gastrocnemius muscle. The use of a free flap is preferred for reconstruction involving obliteration of large-cavity defects, but the isolation of recipient pedicle can be difficult because of the extent of injury zone and in cases of chronic infection around the knee. To provide muscle bulk with a reliable vascular supply, the distally based, prefabricated sartorius muscle flap was used as a last resort to reconstruct difficult wounds with chronic osteomyelitis around the knee joint in 6 patients from June 1995 to May 2001. This method is a two-stage procedure. First, the sartorius muscle is prefabricated by denervation and vascular delay. Silicone sheets are used to increase the vascularity and dimension of the flap. Second, after 3 weeks, the muscle is transposed based on a distal pedicle to reconstruct the soft-tissue defect around the knee. The prefabricated sartorius muscle can provide efficient bulk to obliterate the dead space and to cover moderate-size soft-tissue defects around the knee joint. This method can be considered to reconstruct the soft tissue around the knee joint when local muscle flaps and free flaps are not feasible.

Ideas and technical innovation: a guide for the aligned perforation of vertebral pedicles.

This report presents a guide for aligned perforation of vertebral pedicles. In multi-segment fixation of the spine there are technical problems with the placement of aligned pedicular screws when using rods of a wider diameter. To overcome this problem, a device has been developed to aid the placement of aligned pedicular implants along the longitudinal axis of the spine. The device consists of a track along which flat metal tabs containing orifices slide in both directions. The proximal and distal pedicles are first perforated by the standard technique and Kirschner or Steinman wires are passed through the tabs, fixing the device. The next step is the placement of the tabs in an appropriate position for the perforation of the remaining pedicles. These perforations can be made with drills or probes, according to the preference of the surgeon. After perforation, the Kirschner or Steinman wire is introduced in order to help fixate the device. This procedure is repeated until all pedicles have been perforated. The final steps involve the removal of the wires and of the device, and placement of the pedicular screws.

LAPAROSCOPIC RADICAL PROSTATECTOMY WITH THE HEILBRONN TECHNIQUE: AN ANALYSIS OF THE FIRST 180 CASES

In 1998 Guillonneau and Vallancien introduced laparoscopic radical prostatectomy with primary access to the seminal vesicle. In 1999 we developed a different laparoscopic technique similar to the classic retropubic radical prostatectomy. We focus on early results and the learning curve of the procedure in the first 180 patients. A transperitoneal approach is used with immediate access to Retzius' space. After the dorsal vein complex is endoscopically sutured, the urethra is incised and distal pedicles of the prostate with or without the neurovascular bundle transected. The apex is then pulled ventrally followed with incision at the bladder neck, and transvesical access to vas deferens and seminal vesicle. After completing the posterior wall of the urethrovesical anastomosis with 5 interrupted endoscopic sutures, the Foley catheter is placed, bladder neck closed and specimen extracted via the umbilical incision. From March 1999 to December 2000 we have performed 180 procedures, including 3 for stage pT1 tumor, 88 pT2, 82 pT3 and 7 pT4. Mean preoperative PSA was 13.3 ng./ml. (range 1.4 to 148), mean specimen weight 37.4 gm. (10 to 125) and median Gleason score 6 (3 to 9). For evaluation of the learning curve a separate analysis of 3 groups with 60 patients in each was done. Differences between groups 1 (first 60 patients) and 3 (last 60) were analyzed for statistically significant differences. Mean operating time was 271 minutes (range 150 to 500) and transfusion rate 31%. The reintervention rate was 4.4% and complication rate 18.8%. Of the patients 92% did not require any analgesia on postoperative day 2. Positive margins were found in 16% of the patients. The rate of positive margins in pT2 tumors was 2.3%, pT3a 15% and pT3b 34%. After a median followup of 12 months (range 3 to 23) in 9 (5%) patients a prostate specific antigen relapse was observed. The anastomosis was tight after removal of the catheter in 83% of patients, with a median time of 7 days (range 5 to 30). An anastomotic stricture had to be treated with laser incision in 3.3% of patients. On discharge from the hospital 33% of patients were continent, after 6 months 74% and after 12 months 97%. Analysis of the learning curve revealed significant differences in operating time (324 versus 265 minutes), conversion rate to open surgery (8.1% versus 1.7%), complication rate (23.3% versus 11.7%) and rate of prolonged catheterization (31.6% versus 10%, respectively), whereas the percentage of positive margins and continence rates showed no influence. Laparoscopic radical prostatectomy requires significant laparoscopic expertise with an ongoing learning curve. Morbidity is low, oncological control similar to results of open surgery and functional results are promising. The procedure should be performed only at dedicated centers with adequate training and expertise.

Functional evaluation of the modified Elmslie–Trillat procedure for patello-femoral dysfunction

A series of 28 knees in 27 patients were evaluated at an average of 36 months following surgical treatment for patella dislocation, patello-femoral pain, or a combination of both. All cases were treated by the modified Elmslie–Trillat procedure, which involves a lateral retinacular release and medialisation of the tibial tubercle on a distal pedicle. The evaluation included subjective, objective (Fulkerson and Kujala functional knee scores) and radiographic assessments. Subjectively, eight knees (28%) had excellent results, nine knees (33%) good results and seven knees (25%) fair results, accounting for an overall improvement of 86% over the preoperative status. All the knees in patients with a primary symptom of patella dislocation had an excellent or good subjective result, whilst only four knees (40%) in those patients with a primary symptom of pain and four knees (44%) in those with both pain and dislocation had a good or excellent result. The mean objective knee score was excellent for patients with dislocation only, and fair for those with only pain or both pain and dislocation. There have been no further episodes of dislocation in all patients. Six knees (21%) required later screw removal. The modified Elmslie–Trillat procedure produces a favourable outcome in patients with patella dislocation.

Distant pedicle flaps for soft tissue coverage of severely burned hands: an old idea revisited

Burns to the hand that are complicated by exposure of bone, joint or tendon cannot be closed with conventional skin grafts and require flap procedures to prevent further damage. Local or regional flaps may be unavailable if electrical or blast trauma produces a large zone of injury, or when forearm burn injury extends beyond fascia. Free tissue transfer may not be tolerated by critically ill burn patients. In these circumstances, distant pedicle flaps are one option for safe and effective soft tissue coverage. Over a 5-year period, we have performed six distal pedicle flaps for coverage of exposed hand structures when local or free flaps were contraindicated or unavailable. The patients required an average of 4.5 surgical procedures to complete hand reconstruction and soft tissue coverage. Soft tissue coverage was completely successful in five patients and partially successful in one patient. Single stage local or free flaps remain the treatment of choice when burned hands cannot be covered with skin grafts. When these flap options are not available, distant pedicle flaps provide a safe alternative.

Heilbronn Laparoscopic Radical Prostatectomy

Introduction: In 1999, Guillonneau and Vallancien presented a refined approach of a descending laparoscopic radical prostatectomy which based mainly on the primary access to the seminal vesicles and an improved suturing and knotting technique. Based on our own experience reconstructive laparoscopy as well as with open retropubic radical prostatectomy we have used a combined ascending/descending technique similar to open surgery. In this paper we want to describe our approach and to present the initial results with the Heilbronn technique. Materials and Methods: A transperitoneal approach is used with a W–shaped arrangement of the trocars (13–mm umbilical port, 2×10 mm medial, 2×5 mm lateral ports). After the exposure of the Retzius’ space and control of the dorsal vein complex the urethra is incised and the distal pedicles of the prostate (± the neurovascular bundle) are transsected. We now pull the apex ventrally and start with the incision at the bladder neck followed by a transvesical access to both vasa deferentia and seminal vesicles. The gland is entrapped in the Extraction Bag^®. After accomplishing the posterior wall of the urethrovesical anastomosis with five interrupted sutures, the foley catheter is placed into the bladder and the bladder neck is closed. Now the prostate is extracted via the umbilical incision. From March 1999 to June 2000, we have performed 100 cases (48 pT2–, 47 pT3– and 5 pT4 tumors). The mean preoperative PSA was 26.8 (1.4–75.5) ng/ml. Two tumors were grade 1, 72 grade 2 and 26 grade 3. Median Gleason score was 6 (3–9). All specimen were inked and examined according to the Stanford protocol. Postoperative continence was evaluated using a questionnaire monitored by a colleague who was involved in surgery. Results: We had 5 conversions (rectal injury, difficult dissection, adhesion, 2× bleeding at the dorsal vein complex). The mean operating time was 278 (180–500) min., the transfusion rate 31%. One patient required reintervention due to bleeding from the right obturator fossa. 95% of the patients did not require any analgesia on the second postoperative day. Positive margins were found in 17% of the patients, of which 12 had a PSA nadir to a value of less than 0.1 ng/ml within 3 weeks after surgery. In 82 patients, the anastomosis was tight after removal of the catheter, median catheter time was 8 (6–30) days. 4% developed a stricture at the anastomotic site which could be treated by laserincision. On discharge 33% were continent, after 6 months 81%, whereas only 2 patients still suffer from grade II stress incontinence at 9 months. Conclusions: Laparoscopic radical prostatectomy is feasable but requires laparoscopic expertise. Its learning curve is still ongoing. Morbidity is low, oncological control is similar to results of open surgery, functional results are promising.

The distally pedicled peroneus brevis muscle flap: a new flap for the lower leg.

Defects of the skin and soft tissue in the region of the lateral malleolus of the ankle and the Achilles tendon, resulting in exposed bone, tendons, or osteosynthetic material, cannot be covered with free skin transplants. Local or free flaps must be employed. The authors present the construction of a peroneus brevis muscle flap with a distal pedicle as a useful alternative. Between 1993 and 1999, distal pedicled peroneus brevis muscle flaps were used in 19 patients with various types of defects. During construction of the flap, both the long peroneal muscle and the peroneal artery remained intact. In the region of the distal third of the fibula, consistently arranged branches run from the artery into the muscle, and these form the distal pedicle. The proximal portion of the muscle can be transposed distally and easily extends to the tip of the fibula and the attachment of the Achilles tendon to the calcaneus. Primary healing occurred in 16 patients undergoing flap construction. Donor-site morbidity was mostly limited to the donor-site scar. The distally pedicled peroneus brevis muscle flap is a reliable means for covering defects in the lower leg. This form of muscle flap has not yet been described in the known literature. In the authors' opinion, this flap constitutes a logical and valuable extension of local flap procedures for plastic surgery in the distal leg region.

Torsional rigidity of scoliosis constructs.

A biomechanical study of the rigidity of various scoliosis constructs instrumented with and without caudal pedicle screw anchors and with none, one, or two cross-link devices. To determine whether the increased torsional rigidity provided by distal pedicle screw fixation might make cross-linking unnecessary. Pedicle screws and cross-linking devices have been shown to increase the structural rigidity of spinal constructs. Their relative contributions to scoliosis construct rigidity has not been determined. "Short" (T2-T11) and "long" (T2-L3) scoliosis constructs were mounted on an industrially fabricated spine model and tested in a hydraulic testing machine. Four different short and four different long constructs were tested: hooks only, hooks with concave side thoracic sublaminar wires, hooks with distal pedicle screw anchors, and hooks, distal pedicle screw anchors, and concave thoracic sublaminar wires. There were four iterations for each construct tested: no cross-links, one superior cross-link at T4-T5, one inferior cross-link at T9-T10, and two cross-links. Torsional rigidity was tested by applying a rotational torque at T2. Vertebral body motion was recorded with a three-dimensional video analysis system. Constructs with distal pedicle screws were statistically more rigid in torsion than those with hooks as distal anchors. The additional torsional rigidity from one or more cross-links was negligible compared with that provided by pedicle screws. With pedicle screws as distal anchors in scoliosis constructs, cross-linking with one or two devices adds very little additional rotational stiffness and may be unnecessary in many cases.

Retalho venoso unipediculado transposto comparado ao não transposto: estudo experimental em coelhos

Retalhos venosos são aqueles que apresentam em seu pedículo apenas uma veia, diferente dos retalhos convencionais que são caracterizados por entrada de sangue arterial e saída de sangue venoso. O objetivo deste trabalho foi determinar se a transposição do retalho venoso unipediculado modifica a sua área de sobrevida e vascularização. As orelhas de oito coelhos foram submetidas à realização de retalhos venosos. Dissecou-se um retalho de pele de dois por dois centímetros baseado no pedículo distal da veia marginal anterior. Os retalhos foram divididos em dois grupos: no grupo I(n=8), os retalhos venosos foram levantados e suturados na mesma posição; no grupo II (n=8), os retalhos foram levantados e transpostos 90 graus. Estes dois grupos foram comparados entre si e ao grupo III(n=8), no qual foi realizado enxerto de pele com subcutâneo sobre um leito bem vascularizado. A área média de necrose no grupo I (6,5%) foi significativamente menor que no grupo II (43,75%), e as áreas de necrose dos grupos I e II foram significativamente menor do que no grupo III (88,75%). O estudo angiográfico não mostrou alterações no padrão vascular comparando-se os grupos I e II. A veia marginal anterior foi importante para a sobrevida do retalho. Houve uma maior área de necrose do grupo II, em que foi realizada transposição, em relação ao grupo I.

Arterial anatomy and clinical application of the dorsoulnar flap of the thumb.

After injection of stained latex at the brachial artery, the arterial supply of the dorsal aspect of the thumb was studied by light microscopy in 25 cadavers. An artery, located on the dorsoulnar side and connecting the head of the first metacarpal with the dorsal arcade of the proximal nail fold, was found in all dissections. We report the results of the anatomic study and the clinical applications of a dorsoulnar skin flap that can be raised on its artery with a distal pedicle. Clinical experience is based on 32 flaps. In 25 cases this flap was used for distal skin loss coverage (palmar or dorsal) of the thumb as an island flap. In 7 cases it was used for reconstruction of the finger pulp (5 index and 2 middle fingers) in the form of a cross-finger flap.

The Effects of Tissue Expansion on the Hemodynamic and Survival Characteristics of Reverse-Flow Island Flaps

The effects of tissue expansion on the hemodynamic and survival characteristics of reverse-flow island skin flaps were investigated in New Zealand White rabbits. The animals were divided into 3 groups of 15: group I (control) had no surgery prior to flap elevation, group II (nonexpansion) had a noninflated expander, and group III (expansion) had an inflated expander of 80 ml. After 3 weeks of expansion, a reverse-flow island flap based on the distal saphenous pedicle was elevated. A series of hemodynamic studies was performed to test reverse venous flow--in particular, valve competence. Besides observing the reverse flow under an operating microscope, the changes in the intravenous pressure were measured at 0, 5, 15, 30, 60, and 120 minutes after flap elevation. Moreover, reverse-flow resistance (RFR) was measured in each group to test the competence of venous valves. At each time interval, the values of intravenous pressure were significantly lower (p < 0.01) in group III than in the groups I and II. However there was no statistically significant difference between group I and group II. The RFR was measured as 126.7 +/- 33.52 mmHg in group I, 59.3 +/- 29.86 mmHg in group II (p < 0.01), and 25.1 +/- 7.68 mmHg in group III (p < 0.01). Ten days after flap elevation the mean survival of group III (100%) was statistically higher than that of group I (57.4 +/- 18.3%; p < 0.01) and group II (81.6 +/- 12.8%; p < 0.05). These findings simply suggest that controlled tissue expansion improves retrograde venous drainage and increases the survival of reverse-flow island flaps in rabbits. Abnormal dilatation of the venous tree and incompetence of the venous valves seem to be the main factors in explaining the decrease in the values of RFR and intravenous pressure in the expanded flaps. The potential mechanisms to explain the effects of tissue expansion, and the clinical implications are discussed.

A dynamic study of the circulation in the gracilis muscle in humans.

The aim of the present study was an evaluation of the relative importance of the proximal and distal pedicles for the perfusion of the gracilis muscle flap, as well as to evaluate the importance of the functional connections between the proximal and distal vascular territories. Ten gracilis muscles were investigated in nine patients. They were all operated on in the supine position under general anesthesia. Microcirculatory blood flow (MBF) in the muscle was measured by a dual-channel laser Doppler flowmeter. Two angled probes were sutured opposite to the entry of the proximal and distal pedicles into the muscle, and were kept in place throughout the measurements. Data were acquired on line via a multichannel interface with acquisition/analysis software to a portable computer. The following measurements were done: during baseline with both pedicles intact; during occlusion of the proximal pedicle; after clamp release; during occlusion of the distal pedicle; after clamp release; after motor-nerve transection; and after disinsertion of the muscle from bone attachments. After clamping the proximal pedicle, MBF decreased proximally to 57 +/- 5 percent (p < 0.01), but remained unchanged distally. After occlusion of the distal pedicle, MBF remained virtually unchanged proximally (92 +/- 4 percent, NS), but decreased to 72 +/- 6 percent (p < 0.05) distally. There was a significantly greater decrease in MBF when the proximal pedicle was clamped, than after clamping the distal pedicle (p < 0.01). There was a strong linear correlation (r = 0.85) between the proximal and distal MBF after occlusion of the corresponding pedicle. Transection of the motor nerve resulted in a moderate increase in MBF values proximally (130 +/- 10 percent, p < 0.05), but not distally (108 +/- 18 percent, NS). Detachment of the muscle led to a distinct increase of MBF in both vascular territories (proximally 175 +/- 28, percent p < 0.05; distally 157 +/- 20 percent, p < 0.05). These measurements demonstrated the dominant role of the proximal pedicle in the gracilis muscle in humans. Furthermore, it was shown that each of the two pedicles (proximal and distal) has its own vascular territory, and that both territories are partially connected by intramuscular vascular anastomoses. The predictable extent of blood flow varies in individual cases and should be measured intraoperatively. In cases of marginal perfusion to the distal part of the muscle, a delay procedure should be considered.