Anderson Classification Research Articles

Land Use and Land Cover Map of Ninevah GovernorateUsing Remote SensingData

Changes in the nature of land use activities, in time and space, often result in land cover changes and, as such, are an indication of land management activities. This research represents an attempt to evaluate the ability of using the new version of Anderson's classification system up to the third level in the land use and land cover classifications of Ninevah Governorate using Landsat TM7 imagery. The study area represents one of the most varied and complex geomorphic landscapes in Iraq, and characterized by irregular land use and different land cover in the geomorphic distribution of landforms. Geomorphic agent represent the main factors in the spatial distribution of soil types, lithological escarpments, and the existing land use patterns. The land use and land cover map shows the whole of the apparent activities up to the third level according to the USGS system, and 27 classes of land use are shown in the final map. The results show that visual analyses of satellite images, applying methods similar to those commonly used for aerial photo analysis, are sufficient for observing features shown on 1:100,000 scale Landsat images. Digital classification is appropriate for some applications, but it was found that land use and land cover mapping projects of the type described here are not among them. These data were utilized to draw a new regional land use and land cover map of Ninevah Governorate at a scale of 1:250,000 .

Osteossíntese provisória das fraturas expostas da diáfise da tíbia com fixador externo não transfixante

OBJETIVO: Avaliar a eficácia do fixador externo não transfixante como tratamento provisório das fraturas expostas Gustilo e Anderson graus I e II. MÉTODOS: Em estudo prospectivo, 36 fraturas expostas da diáfise da tíbia foram tratadas seqüencialmente com fixador não transfixante seguido por haste intramedular maciça bloqueada não fresada. A média de idade foi de 28 anos e 88,9% dos pacientes eram do sexo masculino. O mecanismo de trauma foi: acidente motociclístico em 47,1%, atropelamento em 36,1%. Entre os pacientes, nove (25,0%) apresentaram lesões associadas. Segundo a classificação AO, 12 pacientes (33,3%) haviam sofrido fraturas do tipo A, 18 (50,0%) do tipo B e seis (16,6%) fraturas tipo C. Segundo a classificação de Gustilo e Anderson, 13 pacientes (36,1%) eram portadores de fraturas expostas grau I e 23 (63,9%), de fraturas grau II. O tempo médio de fixação externa foi de seis dias, variando de três a 22 dias. RESULTADOS: Entre os pacientes, 32 evoluíram satisfatoriamente. As complicações relacionadas ao fixador existiram em quatro pacientes: em três houve impossibilidade de conversão com o fixador instalado e em um ocorreu neurapraxia do fibular superficial. CONCLUSÃO: O fixador externo não transfixante é útil como fixação provisória das fraturas expostas da diáfise da tíbia quando se visa a conversão para osteossíntese intramedular.

Utilization of the less-invasive stabilization system internal fixator for open fractures of the proximal tibia: A multi-center evaluation

Background:Locked plating has become popular and has clear biomechanical advantages when compared with conventional plating. When combined with minimally invasive surgical techniques, locked plating may cause substantially less iatrogenic tissue damage when compared with conventional plating. These characteristics may make locked plating an attractive option for treating open fractures of the tibial plateau and proximal tibia for which coverage over the plate can be obtained. The purpose of this study was to evaluate the use of the Less-Invasive Stabilization System (LISS) for high-energy open fractures involving either the tibial plateau or proximal tibia.Materials and Methods:This study is a retrospective evaluation of a consecutive multicenter series of 52 consecutive patients operated by seven surgeons, who used LISS plating in open proximal tibia or tibial plateau fractures seen at one of four Level I Trauma Centers. All patients were treated using a locked plating system that was implanted using minimally invasive submuscular surgical techniques. The primary outcome measure was the incidence of deep and superficial infection.Results:Fifty-two patients with open fractures have been evaluated, with a mean follow-up of 16.8 (12–36) months. Three patients (5.8%) developed deep infections. Two patients (6.3%) with tibial plateau and one (4.3%) of patients with a tibial shaft fracture developed deep infections. Fifteen patients required flap coverage of their open wounds. The incidence of deep infection as per Gustilo and Anderson classification was Type I and II – 0 (0%); Type IIIA – 2 (7.7%); Type IIIB – 1 (7.1%); and Type IIIC – 0 (0%).Conclusions:Biomechanically, the LISS functions as an “internal-external fixator” rather than a plate. Traditional plate osteosynthesis has yielded rates of infection between 18% and 35%. Our data indicate that locked plating using minimally invasive techniques yield deep infections rates that are no worse than published series using intramedullary nails or external fixators. Technical difficulties that can be encountered with the LISS system revolve primarily around obtaining and maintaining reduction while performing a minimally invasive procedure. Additional difficulties can include “cold welding” of screws to the plate and malposition of the plate leading to failure in the diaphysis. High-energy open fractures involving the tibia shaft or plateau remain high-risk injuries, but LISS is an acceptable alternative for treatment of these fractures.

Calcanisation of tibia using Ilizarov fixator in crush injuries of hindfoot: a new method

Crush injuries of the foot are one of the most difficult and challenging tasks for a trauma surgeon to manage in terms of limb salvage and provision of a painless functional foot. Injuries to the foot, especially the hindfoot, account for almost 24.6% of all the warfare injuries in Afghanistan, of which more than 70% end in amputation for various reasons. We devised a method using the principles of Ilizarov's distraction osteosynthesis to salvage limbs with bony defects in the hindfoot which otherwise were candidates for amputation. The procedure is done in two stages. Initially, the ring fixator is applied for the soft tissue reconstruction and infection control, and the next stage consists of percutaneous "inverted L"-shaped osteotomy in the posterior half of the lower tibia. The study included 32 patients with hindfoot crush injuries involving talus, calcaneum, a combination of both, or even involving the adjacent tarsal bones. All these crush injuries were classified using the Gustilo and Anderson classification. The postoperative functional assessment of the feet was done using the Maryland Foot Score system with a minimum follow-up of four years. We had good results in 53%, fair in 34% and failure in 13% of our cases. The complications of this procedure were the same as with the use of the ring fixator elsewhere in the body. This method provides a technique to salvage the foot and produce a painless, stable, fused foot in one of the most difficult settings of a hindfoot crush injury.

Locking Compression Plate with Minimally Invasive Plate Osteosynthesis in diaphyseal and distal tibial fracture: A retrospective study of 32 patients

With the introduction of Locking Compression Plates (LCP), Minimally Invasive Plate Osteosynthesis (MIPO) has become widely used. The plates act as internal fixators in a bridging manner, thus resulting in secondary bone healing. We retrospectively evaluated the healing pattern and the clinical evolution of diaphyseal and distal tibial shaft fractures over two and a half years in 32 patients (6 females, 26 males). Fractures were classified according to AO classification and included all 42A-C, 43A-B and 43C1-2 types. For open fractures, Gustillo Anderson classification was used. Plates consisted of the 4.5mm LCP and 3.5mm LCP-Pilon form plate. Clinical and radiological assessment was performed at 6 weeks, and at 3, 6, 9, and 12 months. Two patients were lost to follow-up. Fracture healing was defined as callus bridging of one cortex, seen on both lateral and posterior-anterior X-ray, and full, painless weight bearing. Ten patients at 3 months, 23 at 6 months, and 27 at 9 months met the criteria for a healed fracture. Plate bending was observed in one patient and called for re-operation at 5 months. Two patients required re-operation at 13 months secondary to pseudoarthrosis. Though MIPO seems more advantageous for soft tissue and bone biology, prolonged healing was observed in simple fracture patterns when a bridging plate technique was used.

Therapeutic effects and complications of percutaneous anterior screw fixation for odontoid fractures

To investigate the therapeutic effects and complications of percutaneous anterior screw fixation for odontoid fractures. Twenty-eight patients with odontoid fractures, 21 males and 7 females, aged 38.6 (21-72), 12 with type II fractures and 16 with type III fractures, including 10 cases with shallow type III fractures, according to Anderson's classification system, underwent percutaneous anterior odontoid screw fixation with one screw implant. Five to seven days after the operation the patients got out of bed to conduct dirigation. Prostheses were used for 8-12 weeks post-operationally. The patients were followed up for 43.2 months (26-62 months). Radiological examination, including X-ray and CT examinations, and clinical examinations were carried out to observe the therapeutic effects. Radiological examination showed bony union in 25 cases (89.3%), and non-union developed in 2 cases, 1 case was switched to posterior fusion surgery because of redisplaced fracture. The union rate was 83.3% in the type II fracture, and was 93.8% in the type III. Majority of the patients resumed an excellent cervical motion. No severe complication such as esophagus and carotid artery injury related with puncture was found. One patient had temporary superior laryngeal nerve paralysis, The screw tail was detained at the superior margin of C3 vertebral body in 5 cases, the screw penetrate the tip of odontoid process in 1 case, and the screw thread failed to pass the fracture site entirely in 1 case. An innovative alternative method with the advantages of convenient procedure, less bleeding, gentle injury for surrounding tissue, and rapid recovery, percutaneous anterior odontoid screw fixation is similarly effective as open anterior odontoid screw fixation, for the treatment of odontoid fractures. Related complication is rare and not severe. The surgery has.

Minimally invasive locking plate osteosynthesis for fractures of the distal tibia—Results in 20 patients

We report our experiences with minimally invasive locking plate osteosynthesis (MILPO), for distal tibia fractures, with specific reference to fracture union and complications encountered. Twenty patients underwent MILPO for open and closed distal tibia fractures between March 2003 and December 2004. Fractures were classified according to the AO system. Open fractures were graded using the Gustilo and Anderson classification and closed fractures via the Tscherne classification system. There were 16 males and 4 females of mean age 44.7 years (range 19-69 years). Thirteen patients had temporary external fixation, prior to definitive fracture fixation. Minimum follow-up was 12 months and average time to full weight bearing in the closed fracture group (12 patients) was 18.1 weeks (range 8-32 weeks) and 19.3 weeks in the open fracture group (8 patients, range 8-44 weeks). Fracture healing was defined as radiological evidence of bridging mature callus combined with pain-free full weight bearing. In the open fracture group, four fractures united within 6 months, one within 6-12 months and one united 12 months after surgery; there were two cases of non-union. In the closed fracture group, seven fractures united within 6 months, three fractures between 6 and 12 months and two after 12 months from surgery. Two of the 20 patients required additional procedures to aid bone healing in the post-operative period. Three of the 20 patients required metalwork removal, for delayed wound breakdown in two cases and wound infection in one case. An uneventful recovery was made following this, in all three cases. There was one case of implant failure due to plate breakage at 32 weeks post-op. The fracture site was opened and re-plated at 32 weeks with a DCP. There were no complications following this. MILPO was used for definitive fixation of high energy, open and closed, peri-articular distal tibia fractures. This approach aims to preserve bone biology and minimise surgical soft tissue trauma. This surgical approach may provide an answer to treating a challenging group of fractures and further research is warranted.

Role of ligamentotaxis in management of comminuted intra/juxta articular fractures

Background : Comminuted intra/juxta-articular fractures are the most difficult one's to treat in orthopaedics as far as functional & cosmetic results are concerned. The basic aim of our study was to analyse the efficacy of distractors / external fixator in various forms using principle of ligamentotaxis to achieve a high degree of functional & cosmetic results in these fractures. Methods : This consecutive prospective study comprised of thirty cases of comminuted intra/juxta-articular fractures, varying from grade 0 to grade III B Gustilo & Anderson classification, treated by the principle of ligamentotaxis using distracter / ex fix in its various forms. Results : Average time of union varied from 3 weeks to 20 weeks depending upon the bone involved. Commonest complication was pin tract infection (13), while delayed union (3) and mal­union (one) was also observed. Good range of motion at the involved joint was observed in majority of the cases. As per modified clinical scoring system of Green and O'Brien (1978) excellent to good results were seen in 73.34% cases and fair to poor results in 26.66%. Conclusion : Thus we conclude that ligamentotaxis is an excellent method for the management of comminuted intra/juxta articular fractures. It not only obviates the need of ORIF and/or POP cast but also gives better functional results. It is very useful in compound comminuted fractures around joints where other methods are contraindicated.

Single-centre prospective study of isolated limb perfusion with melphalan in the treatment of subungual malignant melanoma

Subungual melanoma is rare and experience in treating this condition with isolated limb perfusion is limited. Between 1985 and 1990, 24 patients were treated by digital amputation and isolated limb perfusion with melphalan and mild hyperthermia. The disease was staged according to the M.D. Anderson classification: stage I (17 patients), stage IIIA (one), stage IIIB (two) and stage IIIAB (four). Thirteen lesions were on the foot and 11 on the hand. Seven patients have developed locoregional recurrence. The estimated overall 2- and 5-year probabilities of survival were 77 and 46 per cent respectively, while for disease-free survival the rates were 58 and 51 per cent. When these results were compared retrospectively with those in 111 patients treated by amputation alone, no significant difference in survival was demonstrated. This experience suggests that isolated limb perfusion with melphalan and mild hyperthermia confers no additional survival benefit over appropriate surgery.

The Effect of Surgical Delay on Acute Infection Following 554 Open Fractures in Children

Traditional recommendations hold that open fractures in both children and adults require urgent surgical debridement for a number of reasons, including the preservation of soft-tissue viability and vascular status as well as the prevention of infection. Following the widespread use of early administration of antibiotics, a number of single-institution studies challenged the belief that urgent surgical debridement decreases the risk of acute infection. We performed a retrospective, multicenter study of open fractures that had been treated at six tertiary pediatric medical centers between 1989 and 2000. The standard protocol at each medical center was for all children to be given intravenous antibiotics upon arrival in the emergency department. The medical records of all children with open fractures were reviewed to identify the location of the fracture, the interval between the injury and the time of surgery, the Gustilo and Anderson classification, and the occurrence of acute infection. The analysis included 554 open fractures in 536 consecutive patients who were eighteen years of age or younger. The overall infection rate was 3% (sixteen of 554). The infection rate was 3% (twelve of 344) for fractures that had been treated within six hours after the injury, compared with 2% (four of 210) for those that had been treated at least seven hours after the injury; this difference was not significant (p = 0.43). When the fractures were separated according to the Gustilo and Anderson classification system, there were no significant differences in the infection rate between those that had been treated within six hours after the injury and those that had been treated at least seven hours after the injury. Specifically, these infection rates were 2% (three of 173) and 2% (two of 129), respectively, for type-I fractures, 3% (three of 110) and 0% (zero of forty-four), respectively, for type-II fractures, and 10% (six of sixty-one) and 2% (two of thirty-seven), respectively, for type-III fractures (p > 0.05 for all three comparisons). In the present retrospective, multicenter study of children with Gustilo and Anderson type-I, II, and III open fractures, the rates of acute infection were similar regardless of whether surgery was performed within six hours after the injury or at least seven hours after the injury. The findings of the present study suggest that, in children who receive early antibiotic therapy following an open fracture, surgical debridement within six hours after the injury offers little benefit over debridement within twenty-four hours after the injury with regard to the prevention of acute infection.

De novo formation of an aneurysm in a case of unusual intracranial fibromuscular dysplasia

Intracranial fibromuscular dysplasia (FMD) is a vascular disease of unknown origin occurring predominantly in young women. The internal carotid artery is most often involved, but other cerebral arteries may also be affected. We report the case of a young woman presenting with an unusual angiographic appearance of intracranial FMD of the internal carotid artery (ICA) that could not be categorized into any type of the Osborn–Anderson classification. During follow up the patient presented with an intracerebral and subarachnoid hemorrhage. Repeated angiography revealed multiple aneurysms in the pathologic segment of the vessel. The patient underwent surgical treatment with clipping of the aneurysms, wrapping of the pathologic segment of the ICA and biopsy of the superficial temporal artery. Histopathological sections revealed FMD of the intimal type. α 1-antitrypsin blood levels were normal. Cases of intracranial FMD previously reported in the literature are reviewed and various aspects of this rare disease are discussed.

The value of pretreatment clinical and biochemical parameters in patients with newly diagnosed untreated prostate carcinoma and no indications for bone metastases on the bone scintigram.

Between 10% and 25% of patients with newly diagnosed prostate cancer without bone metastases at the time of diagnosis will develop metastases during follow-up. To determine the value of clinical and biochemical parameters for assessment of prognosis at the time of diagnosis, a retrospective study was performed in 124 consecutive patients with newly diagnosed prostate cancer without bone metastases. The mean follow-up was 41 months, during which time 36 patients died and 15 patients developed metastases. Bone scans were classified from 0 (=normal) through 2 (=abnormal, but not typical for metastases) and were correlated with age, alkaline phosphatase (AP), prostate-specific antigen (PSA), tumour grade, T-stage and N-stage. In patients with a class 2 scan, additional roentgenograms and follow-up were used to exclude metastases at initial stage. All parameters, including therapy, were finally correlated with the development of metastases and survival. For survival 38 patients with proven metastases were used as controls. For all parameters tested, no statistically significant differences were found between the three bone scan classifications. The interval between diagnosis and the development of metastases ranged from 12 to 72 months. For the risk of development of metastases only PSA was found to be a significant correlate (P=0.0075). However, when tumour stages were clustered in limited disease (T0-2) and extensive disease (T3-4), the incidence of metastases was significantly higher in patients with extensive disease than in those with limited disease (P=0.0021). Finally, age, PSA and Anderson classification were found to be significant correlates of survival, but in stepwise analysis PSA was selected as the most prognostic variable (P<0.0001). In contrast with a typical pattern of metastases on bone scintigraphy, an abnormal scan (class 1 and 2) at the time of diagnosis is not a poor prognostic parameter of the risk of death. In conclusion, in patients with prostate cancer without bone metastases at the time of diagnosis, pretreatment PSA and tumour stage can be used for the assessment of risk of development of metastases during follow-up and survival. For this purpose, tumour stage should be clustered in limited and extensive disease.

Open tibial fractures treated with the Ex-fi-re external fixation system.

Fifty open tibial fractures were treated with the Ex-fi-re external fixation system from 1987 to 1994. According to the Gustilo and Anderson classification, there were 12 Grade I, 14 Grade II, 10 Grade IIIA, 13 Grade IIIB, and 1 Grade IIIC injuries. Eight fractures were segmental. The average patient patient age was 39 years (range, 16-85 years). With the reduction unit of the system, displaced tibial fractures could be reduced by the functions of the device in contrast to the manual reductions needed with other unilateral devices. Compression could be applied even to oblique fractures. The reductions were performed by this unit in all cases and were classified as exact in 28 of 41 cases. Exact reduction was defined as a reduction in which there was no more than 2 mm of translational displacement. The 8 segmental fractures were not classified according to reduction. Forty-three fractures healed with no secondary procedure. Three secondary bone graftings, 4 fibulotomies, and 3 renamed intramedullary fixations were performed in 6 patients. Thirty-two skin grafts were performed. There was 1 fracture site infection, and 1 curettage and 1 sequestrectomy were performed after union. At 1 year followup there were no signs of infection. Median time to union was 20 weeks, and median time to full unprotected weightbearing was 22 weeks. Fractures with an exact reduction had a median time of union of 19 weeks, compared with a median of 31 weeks in reductions with greater than 2 mm translational displacement. The exact reduction and translational compression applied in oblique fractures appeared to contribute to early consolidation.

Correlation between successive values of Anderson's classification statistic in the hold-out method

Lachenbruch suggested the use of the hold-out method for assessing the chance of misclassification when a new observation is to be classified into one of two normal populations, using Anderson's classification statistic. The successive values of the Anderson statistic, for this method, are then correlated. This correlation in large samples is derived in this paper and its effect on the confidence interval for the true chance of misclassification is investigated.

Hyperthermic isolated limb perfusion for malignant melanoma: response and survival.

Response to and survival after hyperthermic isolated limb perfusion (HILP) with melphalan in patients with malignant melanoma at the Royal Brisbane Hospital were reviewed in order to assess the major determinants of response to treatment. Data were collected by clinical chart review and direct patient contact. Response was assessed by clinical observation and measurement of nodules. Survival was calculated from the date of perfusion to the date of patient death. Since 1965 there have been 85 patients (38 men, 47 women) who have undergone 109 limb (102 leg, 7 arm) perfusions. The mean age was 58 years (range 32-82 years). The number of patients per disease stage (M.D. Anderson classification) was as follows: stage I, 5 patients; stage II, 8 patients; stage IIIa, 41 patients; stage IIIab, 25 patients; and stage IIIb, 8 patients. The mean duration of perfusion was 81 minutes. Melphalan was given in divided doses, with a mean total dose 1.39 mg/kg. The mean maximal limb temperature was 41.5 degrees C. Major complications occurred during 20 perfusions (18%). There was one postoperative death from myocardial infarction, and one patient required amputation. Median patient follow-up was 2.65 years (range 1-27 years). A complete response was noted in 34 patients (40%), a partial response in 36 patients (42%), and no response in 11 patients (13%). Response could not be assessed in four patients. The actuarial 5-year survival for the whole group was 45%: stage I, 80%; stage II, 75%; stage IIIa, 44%; stage IIIab, 23%; stage IIIb, 56%. The two significant determinants of response to perfusion were disease stage (p = 0.00005) and nodal status (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Interobserver reliability in the Gustilo and Anderson classification of open fractures.

The Gustilo and Anderson classification system is widely used to categorize open fractures. To assess its interobserver reliability, 10 patients with open fractures had photographic slides taken of their wound before and after operative treatment. These slides were then shown to a group of orthopaedic surgeons. After an explanation of the Gustilo and Anderson classification system and each patient's pertinent history and physical examination, the physicians were asked to classify the fracture. Agreement among the various raters was determined by Kappa analysis, which is the preferred measurement of interobserver reliability for nominal data such as classification schemes. Kappa analysis demonstrated only moderate agreement among the observers classifying open fractures using the Gustilo and Anderson system. This seems to indicate that, although useful, the Gustilo and Anderson open fracture classification system does have limitations; studies and treatment recommendations based on it should be interpreted with caution.

Isolated regional perfusion in the treatment of subungual melanoma.

Subungual melanoma is rare and represents only 1% to 3% of all diagnosed melanomas in Western countries. The tumor is frequently mistaken for a benign lesion and the delay in diagnosis and final treatment may be responsible for the high local recurrence rate and the low disease-free survival rate. From 1965 to 1982 the combined-modality therapy of amputation and adjuvant isolated regional perfusion with melphalan with or without dactinomycin was used in the treatment of 22 patients with subungual melanoma. Disease was staged according to the M. D. Anderson classification, as follows: stage I (primary melanoma), 11 patients; stage IIIA (in-transit metastases and/or satellitosis), three patients; stage IIIB (regional lymph nodes), seven patients; and stage IIIAB (in-transit metastases and/or satellitosis and regional lymph nodes), one patient. There were no cardiovascular complications and no treatment mortality. During a follow-up of at least 4.5 years, 12 patients (55%) developed distant metastases, including four patients with stage I disease (36%) and eight patients with stage III disease (73%). There were no locoregional recurrences. The median survival was three years (range, 0.5 to 12.5 years) and the overall five-year survival was 40%, with 56% of patients having stage I disease and 27% having stage III disease. The prognosis of subungual melanoma is determined by the stage of the disease. Isolated regional perfusion may prolong disease-free survival in patients with subungual melanoma compared with previously published data.

Hyperthermic isolated regional perfusion in the treatment of extremity melanoma in children and adolescents

From 1973 to 1982 six children and eight adolescents with extremity melanomas were treated by local excision and adjuvant hyperthermic isolated regional perfusion with Melphalan (L-phenylalanine mustard, manufactured by Burroughs Wellcome Company, Research Triangle Park, NC). The median Breslow thickness of the melanomas was 2.7 mm (range, 1 to 15 mm). According to the M.D. Anderson classification, nine patients were in Stage IA and five were in Stage IIIB. The median follow-up period was approximately 10 years. Distant metastases developed in three patients (21%) (one patient was in Stage IA [11%] and two patients were in Stage IIIB [40%]). In two cases the development of distant metastases was preceded by local recurrence (14%). The 5-year survival rate was 93%. The 10-year survival rate was 81%. The high survival rate, even for patients with unfavorably thick melanomas, seems to be attributable to isolated regional perfusion.

Anderson's classification statistic based on a post-stratified training sample

The performance of Anderson's classification statistic based on a post-stratified random sample is examined. It is assumed that the training sample is a random sample from a stratified population consisting of two strata with unknown stratum weights. The sample is first segregated into the two strata by post-stratification. The unknown parameters for each of the two populations are then estimated and used in the construction of the plug-in discriminant. Under this procedure, it is shown that additional estimation of the stratum weight will not seriously affect the performance of Anderson's classification statistic. Furthermore, our discriminant enjoys a much higher efficiency than the procedure based on an unclassified sample from a mixture of normals investigated by Ganesalingam and McLachlan (1978).

Covariate classification by post–stratification

The plug–in Anderson's covariate classification statistic is constructed on the basis of an initially unclassified training sample by means of posty–stratification. The asymptotic efficiency relative to the discriminant based on an initially classified training sample is evaluated for the case where a covariate is present. Effect of post–stratification is examined.