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Full-endoscopic spine surgery (FESS) indications already cover pathologies such as degenerative, infectious, and neoplastic diseases. This paper aimed to use a bibliometric search and meta-analysis of the highest quality studies in the last twenty years to determine the quantity and quality of FESS research, geographical distribution, and the outcomes for lumbar conditions.Articles on FESS published from 2000 to 2022 were screened and assessed through the Web of Science, PubMed, and Scopus. Also, databases were searched for longitudinal studies to pool in a meta-analysis of patients undergoing FESS for lumbar conditions. After stratifying the risk of bias and having collected the papers of the highest quality, we acted the proportion of patients with a satisfactory outcome and intraoperative and postoperative adverse events after the analysis of lumbar spine conditions.A total of 728 articles were identified by the bibliographic search. Between 2000 and 2021, the published articles increased 21 times. Most were from China (70.15%), followed by South Korea (19.5%). Most were retrospective (68.3%) and regarding lumbar pathologies treatment (86.4%). Fifty studies, including 34828 patients, were pooled in the meta-analysis. Over 85% of patients experienced satisfactory improvement in each of different lumbar conditions. Major adverse events were2%; recurrence and postoperative dysesthesia rates were within those reported for open or mini-invasive procedures.This study may fill research gaps on FESS, and lead to adequately designed studies. Our meta-analysis showed that FESS for lumbar pathologies is a procedure with satisfactory outcomes and low rates of adverse events.

Introduction Temporal engagement may persist after etiologic surgical treatment of acute subdural hematoma (ASH) without clinical improvement despite normalized intracranial pressure (ICP). The aim of this study was to assess the feasibility of secondary direct temporal lobe disengagement (DTLD) after surgery for supratentorial ASH and to evaluate clinical outcome. Materials and methods This was a retrospective analysis of 4 patients undergoing secondary DTLD. Patient data were recorded at admission, pre- and postoperatively and at 6 months’ follow-up (FU): age, gender, Rotterdam score, Glasgow Coma Scale (GCS), neurological deficits, oculomotor nerve palsy (ONP), ICP, midline shift, complications and Extended Glasgow Outcome Scale (GOS-E). Results At postoperative evaluation 48 h after DTLD, we observed a significant improvement in GCS score (initial 6 ± 3, preoperative 7 ± 3, postoperative 14 ± 1; P = 0.02), midline shift (initial 16 ± 3 mm, preoperative 13 ± 5 mm, postoperative 9 ± 2 mm; P = 0.049) and ONP (P = 0.01). In all cases, early postoperative imaging documented visualization of a patent ipsilateral peri-mesencephalic cistern. At 6-month FU, GOS-E showed 75% good recovery and 25% disability. Complete ONP recovery was observed in 75% of patients (P = 0.01). Neurological deficits were present at FU in 25% of patients. No surgery-related complications or mortality were recorded. Conclusions In traumatic brain injury, secondary DTLD may allow simple, effective and safe management of trans-tentorial uncal herniation, avoiding more challenging procedures. Clinical results are promising, as this technique seems to favorably influence neurological outcome in this selected subgroup of patients with persistent clinical and radiological signs of temporal engagement after etiological treatment with normal ICP values.

The treatment strategy for thoracolumbar burst fractures is still debated. The aim of this study is to evaluate clinical and radiologic outcomes of a 2-stage strategy with immediate posterior percutaneous instrumentation and delayed anterolateral fusion (group A) versus a single-stage open posterior instrumented fusion (group B).Demographics and clinical and surgical data of patients operated for AO Spine A3 and A4 fractures were prospectively collected. Vertebral height and deformity were evaluated before and after surgery. Visual analog scale score for back pain, Oswestry Disability Index, and 12-Item Short Form Health Survey results for quality-of-life assessment were collected during follow-up.Among the 110 patients enrolled, 66 were allocated to group A and 44 to group B; the most common fractured level was T12 (34%). Postoperative complications were higher in group B, especially the wound infection rate (18% vs. 3%), and pseudomeningocele (14% vs. 0%). The 2-stage approach allowed an average long-term gain of 15.8° at the local kyphosis of fractured vertebra and 5.8° at the regional level (Cobb angle), versus 15.4° and 5.5° in group B. At 2 years follow-up, both groups showed significant functional improvements; however, the visual analog scale and Oswestry Disability Index metrics seemed more favorable for group A patients (P0.0001 vs. P0.003). A complete fusion rate was obtained in 100% of group A vs. 65% of group B.Our study indicates that percutaneous instrumentation and anterior fusion or an expandable cage lead to excellent long-term clinical and radiologic outcomes with a lower complication rate and higher fusion rate than those of open posterior approaches.

BACKGROUND: Thoracolumbar fractures sometimes require anterior support and post-traumatic deformity correction. SpineJack proved favorable results in cadaveric and clinical studies, with satisfactory pain relief, vertebral height restoration, and low rates of above adjacent fractures, in neurologically intact fractures. We compared patients' clinical and radiological outcomes of thoracolumbar fractures treated either with posterior arthrodesis or SpineJack. METHODS: We prospectively collected A2 split and A3, and A4 burst fractures between 2017 and 2021. Patients were stratified in posterior arthrodesis (PA group) and SpineJack (SJ group) and included if age ≥18 years, T11–L3 level, emergent or elective surgery, single or multiple, and neurologically intact. Age, sex, type and level, pain, operative and discharge time, vertebral body heights (VBH), posterior wall retropulsion (PWR), vertebral kyphosis (VK) and local kyphosis (LK) angles, vertebral body (VB) volume, and complications were collected. We then compared clinical-radiographic outcomes between the two groups. RESULTS: We found no significant differences in median postoperative pain while operative time and discharge time were shorter for SJ patients than PA ones (P

BackgroundThere is no consensus regarding the best treatment option for unruptured aneurysms of the posterior communicating artery (PCom) presenting with oculomotor nerve palsy (ONP). We aimed to assess predictors of ONP recovery in a multicenter series of consecutive patients.Materials and methodsA retrospective review of prospective databases in three tertiary neurosurgical centers was carried out, selecting patients with ONP caused by unruptured PCom aneurysms, treated by surgical clipping or embolization, between January 2006 and December 2013. Patient files and imaging studies were used to extract ophthalmological assessments, treatment outcomes, and follow-up data. Predictors of ONP recovery during follow-up were explored using univariate and multivariate analyses.ResultsWe identified 55 patients with a median ONP duration before treatment of 11 days (IQR 4.5–18); the deficit was complete in 27 (49.1%) and incomplete in 28 (50.9%) cases. Median aneurysm size was 7 mm (IQR 5–9). Twenty-four (43.6%) patients underwent surgical clipping and 31 (56.4%) embolization as the primary treatment. Overall, ONP improved in 40 (72.7%) patients and persisted/recurred in 15 (27.3 %). Surgery, interval to complete treatment ConclusionThere was no significant difference in ONP recovery between surgical clipping and embolization. The best predictor for ONP recovery was timely, complete, and durable aneurysm exclusion.

Background Intracranial solitary fibrous tumors (ISFTs) are rare mesenchymal neoplasms originating in the meninges and characterized by very different biologic and clinical behaviors. Benign histotypes, such as hemangiopericytomas, are now considered a cellular phenotypic variant of this heterogeneous group of rare spindle-cell tumors. Owing to their rarity and resemblance to other, more common brain tumors, ISFTs are often poorly recognized and remain a diagnostic challenge. Methods We describe a surgical series of 29 patients treated for ISFTs confirmed histologically and through immunohistochemistry. We attempt to provide a focus on the natural history of these pathologies and the need for tailored management. Results This was a retrospective consecutive series of 29 patients with either solitary fibrous tumor (n = 14) or hemangiopericytoma (n = 15) over a 10-year period. Mean follow-up time was 37.71 months. Recurrence rate was 42.9% for solitary fibrous tumors versus 26.7% for hemangiopericytomas. STAT6 expression was 66.7% in hemangiopericytomas versus 42.9% in SFTs. Conclusions Histopathology and immunohistochemical staining (characterized by positive expression of mainly STAT6 but also CD34, Bcl-2 protein, and vimentin) are key in diagnosis and management of ISFTs. Although ISFTs are still considered benign lesions with very rare aggressive evolution, their clinical behavior is largely unpredictable. This study highlights the importance of relying on immunohistochemistry for a thorough definition of the management strategy.

Introduction A dura mater substitute in decompressive craniectomies must protect the brain while providing a dissection plane between the cortex and myocutaneous layer. The human amniotic membrane (AM) has anti-inflammatory, wound healing, and differentiation properties. We tested AM properties as a dural substitute by comparing the outcomes to biological ones. Methods We prospectively collected data on 25 patients who randomly underwent decompressive craniectomy with lyophilized AM patches and 25 in which biological substitutes were utilized between 2015 and 2019. The AM was laid with the epithelial side facing the brain because of the anti-adhesive proprieties, while the chorion facing the myocutaneous flap. We collected data on demographics, neurological status, comorbidities, and surgical outcomes. Additionally, we created a score – dura mimicking score– and reviewed postoperative imaging and pathological specimens. Results The majority (96%) of AM grafts were integrated into native dura. Thirteen patients scored as excellent and 11 good on our “dura mimicking score”, showing tissue integration ability but no cerebral cortex adhesion. The histopathological analysis showed that AM had thick plates of dense fibrous tissue with small reactive vessels, reactive fibroblasts, and lymphocytes infiltrate. The AM group's first outcomes were not different from the biological substitute patients but higher integration rate to the dura and less adhesion to the myocutaneous flap in AM patients. Conclusions We documented the anti-adhesive, protective, and integrative properties of AM dural substitute patches in patients who underwent decompressive craniectomies, comparing the intraoperative differences and postoperative outcomes to biological dural substitutes.

Objective Opto-chiasmatic (OC) cavernous malformations are sporadic lesions that are often misdiagnosed clinically and radiologically. Presenting symptoms range from incidental findings to the more frequent and dramatic "chiasmal apoplexy." The present study aims to evaluate the potential role of arachnoidal membranes of the basal cisterns in the onset of OC apoplexy. A possible mechanism resembling a compartment syndrome is discussed through the description of two cases of bleeding cavernomas. Methods We describe clinical, radiological, intraoperative findings in two cases of young patients presenting with OC apoplexy from bleeding cavernoma. The first was a 38-year-old man diagnosed with optic neuritis at the first episode of visual acuity deterioration. The second patient was a 22 -year-old woman who suffered two OC apoplexy episodes from a recurrence, which also presented with bleeding. Results Both patients were operated on via pterional craniotomy and presented a postoperative improvement of visual symptoms. The second patient experienced deterioration 30 months after surgical resection due to rebleeding from a recurrence and required a second operation. Follow-up revealed a good recovery of visual disturbances; MRI at 6 and 3 years showed in both patients an apparent complete removal of the cavernous malformations. Conclusion The cisternal environment where OC cavernous malformations develop and the paradigm of a compartment syndrome could explain the clinical presentation variability. This very rare subset of cavernomas would benefit from a classification system using ad hoc neuroimaging protocols and consistent indications.

Background Secondary cranioplasty (CP) plays a key role in restoring cranial vault anatomy and normal brain function following decompressive craniectomy (DC). The scientific literature provides only fragmentary information regarding the best timing and material for CP, making a direct comparison of different materials difficult. Object To identify and report according to STROBE guidelines local trends in choice of materials for CP, complications rate and surgical outcomes. Methods We conducted an audit on secondary CP covering the last 20 years of surgical practice at our Institution. Custom-made CP used over the years were made of: porous hydroxyapatite (PHA), polymetylmethacrylate (PMMA), polyetheretherketone (PEEK), acrylic and titanium. The primary endpoint of this study was the incidence of postoperative complications, such as: implant infection, fracture and dislocation. Secondary endpoints were the followings: patients satisfaction with cosmetic result, rate of implant integration, and long-term neurological outcome. Results A total of 218 patients were included, given the predominance of PHA (Group A) or PMMA (Group B) CP, a direct comparison was made only between those two groups. Overall reoperation rate was 6.5% versus 28%; implants’ osseointegration rate was of 69% versus 24%; satisfaction rate was 66% versus 44%, in Group A and B respectively. Conclusions This single-centre study provides Level 3 evidence that PHA yields better outcomes than PMMA CP. Designing a management algorithm for planning and executing CP is difficult for clinical and organizational reasons; till a widespread consensus is reached, neurosurgeons with subspecialty interest in neurotrauma should favor pragmatism and patient safety over costs.

Background Transorbital neuroendoscopic (TONES) approaches promise to open up new horizons for skull base surgery, offering alternative routes to reach the anterior and middle cranial fossa (ACF and MCF, respectively). Objective The aim of this anatomical study is to acquire new surgical anatomy knowledge and exploit it for the refinement of TONES approaches, as an alternative to open surgery, to reduce the distance to the target, and the risk of neurovascular lesions in pathological conditions extending beyond the orbital cavity. Materials and Methods Six head specimens (12 orbits) were studied/dissected. The orbit was approached and divided in a four clockwise quadrants manner to simulate three transconjunctival routes: the precaruncular (PC), preseptal (PS), and lateral retrocanthal (LRC), and one transpalpebral route—the superior eyelid crease (SLC). The boundaries and the most important anatomical landmarks were identified and are herein duly detailed with particular attention to the neurovascular structures encountered in each of those routes. Results The dissections showed that the PC approach facilitates the treatment of optic nerve and frontal sinus pathologies, whereas LRC appears safer to reach ACF and MCF allowing for a free multiplanar working channel (up to 180 degrees) to the floor, roof, and lateral-to-medial walls. Conclusion The plane of tendon lateral canthal's insertion and the sphenofrontal suture (SFS) were identified as the key anatomical landmarks for TONES approaches. Further studies are warranted to establish a practical clinical algorithm based on the anatomical four clockwise quadrants herein implemented/proposed, and the key surgical landmarks identified.

Background Prostate carcinomas rarely metastasize to the central nervous system but, when they do, dural localizations are as common as and far more aggressive than intraparenchymal ones. Those metastases can be further classified according to their extension toward the subdural or extradural space and can frequently simulate other pathologic conditions including chronic subdural hematomas, abscess, and primary bone tumors. Beside the challenges of the preoperative differential diagnostic and complexity of surgical planning and operative excision, subdural metastases seem to carry a much poorer prognosis. Methods A series of consecutive patients admitted during a 12-year period through our oncall pathway for subdural/extradural collections or intraparenchymal lesions found, on histologic analysis, to represent intracranial prostate cancer metastases was retrospectively reviewed. Results A total of 19 patients were included, but only 3 were diagnosed with small cell prostate carcinoma, while the majority had a primary prostate adenocarcinoma. Metastases could be classified as pure subdural space lesions, dural-based lesions, extradural/bony lesions, and pure intraparenchymal lesions. All patients with subdural metastases and 3 out of 5 patients with dural-based lesions required an emergency intervention due to rapidly deteriorating neurologic status. The mean follow-up in our series was 37 months; only subdural localizations had a remarkably unfavorable outcome. Conclusions Supported by our experience and the review of the literature, we suggest that a low threshold for contrast-enhanced computed tomography/magnetic resonance imaging is advisable in case of suspicious subdural collection, even in an emergency setting, for patients with previous medical history of prostate cancer.

This prospective study was conducted on 108 consecutive implantations of a straight, cementless, taper-designed stem with variable lateral flare (Pegasus; DePuy, Warsaw, Indiana) at an 8- to 10-year follow-up; DEXA scanning was performed at 3 and 12 months on a second cohort of 40 patients. The mean Harris hip score was 94.2, and no revision was performed. Measurable subsidence of the stem was found in three (2.8%) patients; the subsidence was always measured within the first year of follow-up, and did not progress at the subsequent controls. Bone mineral density decreased at 1 year, 15.1% in zone 1 and 3.4% in zone 7. Uncemented stems with a taper design, which provide a high metaphyseal fit and a low diaphyseat fit, lead to comparable and reproducible long-term results independently from other design characteristics.

Pin tract infection is a frequent complication of external fixation; according to literature its frequency ranges from 2-30%. The recent introduction of silver coating of polymeric materials was found to decrease bacterial adhesion; its clinical use with Foley catheters and central venous catheters led to significant results. To verify the ability of the same silver coating to decrease the bacterial colonization on external fixation screws, a prospective randomized study was carried out on 24 male patients; a total of 106 screws were implanted in the lower limb to fix femoral or tibial diaphyseal fractures: 50 were coated with silver and 56 were commercially available stainless steel screws. Although the coated screws resulted in a lower rate of positive cultures (30.0%) than the uncoated screws (42.9%), this difference was not statistically significant (p = 0.243). The clinical behavior of the coated screws did not differ from that of the uncoated ones. Furthermore, the implant of silver-coated screws resulted in a significant increase in the silver serum level. These results led us to consider it ethically unacceptable to continue this investigation.

Precise pre-op planning is fundamental for surgical precision in fit and fill of uncemented prostheses, and reliable and comparable radiographs are necessary for the early diagnosis of loosening. All this can be obtained with a given X-ray magnification factor. The Authors prove that the routinely used methods are misleading and suggest a new technique to obtain a uniform and/or measurable magnification in the A.P. radiograms of the hip. The method gives accurate measurements within a few tenths of a millimetre. It is based on the knowledge of the femoral position in relation to the X-ray film, obtained with a lateral radiographic view, and on mathematical calculation to obtain the X-ray focus height and position. Also in the case of a flexed and externally rotated hip, the non-uniform longitudinal and transverse magnifications can be measured.

Background: The lack of knee flexion represents a possible complication in severe femur fractures. In 1956, Judet proposed a quadricepsplasty technique that allowed for a graded release without the disruption of the vastus medialis obliqus, vastus lateralis, or rectus femoris. Methods: This article reports the clinical outcome of 21 cases of Judet quadricepsplasty after an average follow-up of 101.0 months (range, 21-204 months). The definitive flexion gain was classified as excellent, good, fair, or poor. Excellent when >100 degrees, good when >80 50 degrees

The packaging and chemical stability of both conventional and highly crosslinked polyethylene (PE) components available for clinical use in Italy were analyzed. A total of 100 sterilized PE components were entered by 18 orthopedic manufacturers into the study. Six of the manufacturers were Italian and the remaining were based in Europe or America. Hydroperoxide, oxidation, and trans-vinylene levels within the PE components were characterized using Fourier-transform infrared spectroscopy (FTIR). None of the 31 gas-sterilized components had detectable free radicals, hydroperoxide content, or oxidation. Among radiation-sterilized inserts, the highest oxidation and hydroperoxide levels were associated with gas-permeable and polymer-barrier packaging. To the authors' knowledge, this is the first study that relates elevated oxidation and hydroperoxide content in γ-sterilized PE components to certain types of contemporary, polymeric barrier packaging. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006

The focus of this work was to study the serum interleukin-6 (IL-6) response to total hip replacement. Twenty-one patients received an uncemented total hip prosthesis. Venous samples for IL-6 determination were drawn before and after surgery. The IL-6 response was significant, and a peculiar heterogeneity of response was apparent: the medians of peak levels (82.3 pg/ml) and of areas under the response curve (51.8 pg/ml) distinguished between IL-6 high responders (HR) and IL-6 low responders (LR; p

Hydatid disease involves mainly the liver (66% of the cases) and the lungs (22%), with skeletal involvement being reported in 0.5-2.5% of cases.Herein is reported a case of hydatidosis of the hip and pelvis with a follow-up of 25 years. The diagnosis was first done in April 1975 following the local excision of a single hydatid cyst from the ischium of a 25-year-old man complaining of increasing pain and swelling of the left thigh. Histology confirmed hydatid disease of the bone. Local excision was repeated four more times for recurrence of the hydatid cysts in the bone or soft tissues. Antiparasitic medical therapy (albendazole 10 mg/kg daily) was attempted in 1991 but suspended after 2 days due to systemic adverse effects (abdominal pain, diarrhea). The patient had a 12-year relapse-free period with complete absence of any symptoms.Such a long symptom-free period confirms that it is not possible to consider bone hydatidosis as being completely healed without the confirmation of a long term follow-up.

Ten new polyethylene prosthetic components (PEs), ethylene oxide (EtO)- and gamma-sterilized, were studied by means of infrared (IR) analysis in order to evaluate oxidation. Using attenuate total reflection infrared spectroscopy the authors demonstrate that all samples show surface oxidation, formed during processing and shaping, related to mechano-degradation. By means of Fourier transform infrared (FTIR) microscopy and derivatization techniques, the EtO-sterilized PEs present different behaviour in comparison to the gamma-radiated. The former show low levels of depth oxidation that could be related to the degradation which occurred during preparation of slices for IR analysis. The gamma-sterilized PEs show higher oxidation levels, variable from sample to sample, on the surface and in the bulk. The authors demonstrate that oxidation is described both by carbonyl species distribution and by hydroperoxide concentration. The hydroperoxides could be responsible for oxidative PEs ageing in in vivo service. The different oxidation levels and distribution could depend on the conditions of gamma-sterilization, in particular on the rate of the dose absorbed, not previously reported for ready-to-implant PEs. Chain scission of gamma-radiated UHMWPE, estimated by IR analysis, results in reduction of molecular weight and consequently in less abrasive resistance. The scheme of UHMWPE oxidation due to gamma-sterilization demonstrates the inhomogeneous distribution of reactive species in PEs responsible for the unpredictable performance in vivo.

The chemical characterization of 19 retrieved ultra-high-molecular-weight polyethylene tibial plateaux, six new ones and one raw bar was performed by means of infrared spectroscopy. The surface and bulk oxidation and biodegradation indexes were calculated. The raw bar has a measurable oxidation, which increases on the bulk and on the surfaces of the new plateaux. In the retrieved plateaux, the average oxidation index increases further both on the bulk and on the surfaces; the worse values were present on the worn area. Similar results were found for the biodegradation index. The data show that the biotic in vivo degradation is promoted by the oxidation present on the new plateaux and that it occurs through a different mechanism, abiotic thermal-, photo-, γ-radiation oxidation, evaluated by the oxidation index.

1 Iannuzzi MC, Rycicki BA, Teirstein AS. Medical progress: sarcoidosis. N Engl J Med 2007; 357: 2153–65. 2 Newman LS, Rose CS, Bresnitz EA, et al. A case control etiologic study of sarcoidosis: environmental and occupational risk factors. Am J Respir Crit Care Med 2004; 170: 1324–30. 3 Kucera GP, Rybicki BA, Kirkey KL, et al. Occupational risk factors for sarcoidosis in African-American siblings. Chest 2003; 123: 1527–35. 4 Rafnsson V, Ingimarsson O, Hjalmarsson I, Gunnarsdottir H. Association between exposure to crystalline silica and risk of sarcoidosis. Occup Environ Med 1998; 55: 657–60. 5 Rybicki BA, Iannuzzi MC. Epidemiology of sarcoidosis: recent advances and future prospects. Semin Respir Crit Care Med 2007; 28: 22–35. a cobalt-chromium head, or could the placement of a cobalt-chromium head in combination with the previously inserted ceramic socket explain the loss of cobalt-chromium? After the resection arthroplasty, the patient’s vision “partially improved”, while “metal ion concentrations decreased but remained higher than reference values”. These statements do not prove any clear relation to the operation. We believe this Case Report generates more questions than answers and leaves physicians with unnecessary concerns about the safety of total hip replacement. Furthermore, we believe this patient was left with a disabling condition. Did the authors panic and become blind and deaf to the evidence of the superior wear characteristics of modern hip prostheses?

A fibre-shaped glass with qualities of biocompatibility and biodegradation could be promising for reconstructive bone surgery in orthopaedics and neurosurgery. New highly biocompatible glasses, originally made by the Italian Group of Study on Biocompatible Glass, are obtained both in cylinder and fibre shapes due to their original chemical composition (Glassfiber®). This is the only glass which is also available as a continuous filament. Hydrolytic in vitro and in vivo tests demonstrate that these glasses present both good biocompatibility and adjustable biodegradation in relation to their chemical composition. The advantages of bioactive glass also being available as a continuous filament are suggested.

Eighty-eight bipolar Bateman hip endoprostheses for medial femoral neck fractures were implanted. The average age of the patients was 75 years. Intrahospital results proved the morbidity and mortality rates to be well within acceptable limits. Thirty patients were followed during periods of 12-74 months (median, 33 months). According to Charnley evaluation, mobility was excellent and very good in 20 patients (86%). Good function was present in 63% of patients. The majority of patients belonged to category C as defined by Charnley. Mild pain was present in 19 patients (63%); in only two cases, involving severe rheumatoid arthritis, pain was clearly related to sinkage. Radiographically, no visible protrusion or socket wear was present. Periarticular ossification occurred in 19 patients, but this did not impair function.

The specific radiological manifestations of primary bone healing have been known for over fifty years. In 1914, Lane (22), referred to it is as “bone healing by primary intention” and in 1949, Danis (10), described it as “soudure autogene”, or autogeneous welding. It was also known that rigid internal fixation was a “sine qua non” condition to obtain the specific pattern of healing which is characterized by the absence of callus. It has not been clear,though, whether the effect of compression is biological, or whether the callus-less healing occurs simply due to the stabilizing effect (8). Despite the uncertainty as to the cause of the beneficial effect of rigid fixation, the clinical use of compression plates gained broad recognition since their introduction by Danis in 1949 (10). Venable in 1951 (34), Boreau and Hermann in 1952 (7), Bagby and Janes in 1957 (5) described similar fixation devices. In 1955 Yamagishi and Yoshimura (37) published an experimental paper in which a moderate intermittent compression was considered to be the ideal biomechanical condition for fracture healing. According to the modern philosophy of the Russian Ilizarov, this concept is fun damental. However in 1958 Bagby and Janes (6) carried out experiments on dog femurs and concluded that a steady compression does not necessary stimulate the osteogenesis,although it is a main factor in increasing stability. In the sixties a number of histolo gical observations on primary bone healing in various species including humans were reported (2,24,26,29,32,33). Most of the work in this field came from the Work Group for the Study of Osteosyn-thesis, which was founded in Switzerland by M.E. Muller,M.Allgover and H. Willenegger in 1958. Laboratory facilities for the experimental work on the animal were provided in Davos in the “Laborato- rimn fur experimentelle Chirurgie” headed by Stephan Perren. Most of the work described in this paper in detail on the histology of primary bone healing was performed there. Further research in the same laboratory, working on sheep, showed that a pattern of secondary healing with callus was produced when internal fixation allowed for some interfragmentary motion (no compression). The amount of callus observed corresponded to the deformability of the implant and consequently to interfragmentary motion (17).

Die Definition der fehlenden Knochenbruchheilung, der verzogerten Knochenbruchheilung und der Pseudarthrose ist nicht nur ein theoretisches Problem, sondern auch eine Zeitfrage, denn idealerweise sollte die Therapie erfolgen, sobald die Mechanismen der Frakturheilung sistieren. Anstatt Zeit zu verlieren, um auf das klinisch-radiologische Bild der fehlenden Knochenbruchheilung zu warten, ware es besser, die Kriterien der Heilungstendenz zu definieren. Diese Kriterien lauten: —Wolkiger Knochenkallus —Unveranderte Verkurzung —Eingeschrankte Beweglichkeit —Fehlende Heilung der Fibula (Unterschenkelfrakturen)