We assessed the reproducibility and accuracy of four ratios used to measure patellar height, namely the Blackburne-Peel, Caton-Deschamps, Insall-Salvati and modified Insall-Salvati, before and after total knee arthroplasty. The patellar height was measured, by means of the four ratios, on the pre- and post-operative lateral radiographs of 44 patients (45 knees) who had undergone total knee arthroplasty. Two independent observers measured the films sequentially, in identical conditions, totalling 720 measurements per observer. Statistical analysis, comparing both observers and ratios, was carried out using the intraclass correlation coefficient. Before operation there was greater interobserver variation using either the Insall-Salvati or modified Insall-Salvati ratios than when using the Caton-Deschamps or Blackburne-Peel methods. This was because of difficulty in identifying the insertion of the patellar tendon. Before operation, there was a minimal difference in reliability between these methods. After operation the interobserver difference was greatly reduced using both the Caton-Deschamps and Blackburne-Peel methods, which use the prosthetic joint line, compared with the Insall-Salvati and modified Insall-Salvati, which reference from the insertion of the patellar tendon. The theoretical advantage of using the Insall-Salvati and modified Insall-Salvati ratios in measuring true patellar height after total knee arthroplasty needs to be balanced against their significant interobserver variability and inferior reliability when compared with other ratios

We studied serial CT scans of 45 arthritic shoulders (34 rheumatoid, 11 osteoarthritic) and 19 normal shoulders, making measurements at three levels on axial images. The maximum anteroposterior diameter of the glenoid was increased in rheumatoid glenoids at the upper and middle levels by 6 mm and in osteoarthritic glenoids at all levels by 5 to 8 mm as compared with normal. In rheumatoid cases, nearly half the available surface of the glenoid was of unsupported bone, mainly posteriorly at the upper and middle levels. In osteoarthritic glenoids, the best supported bone was anterior at the upper level and central at the middle and lower levels. The depth of the rheumatoid glenoid was reduced by a mean of 6 mm at the upper and middle levels and by 3 mm at the lower level. This inclined the surface of the glenoid superiorly. The depth at the middle level in osteoarthritis was reduced by a mean of 5 mm, suggesting central protrusion. Osteoarthritic glenoids were retroverted by a mean of 12.5 degrees, but of rheumatoid glenoids two-thirds were retroverted (mean 15.1 degrees) and one-third anteverted (mean 8.2 degrees). Our findings have important implications for the planning and placement of the glenoid component of total shoulder replacements; CT can provide useful information

We made a clinical study of polyethylene wear in 240 hips of 187 patients having primary total hip arthroplasties from 1989 to 1990, using uncemented Osteonics components, with a head size of 26 mm. We excluded cups with anteversion of over 20° and measured linear wear by a new method using a digitiser and special software of our design. Follow-up was from two to five years (mean 4.3). The mean age at operation was 50.3 years, with more men than women (1.4:1). The mean linear wear per year was 0.15 mm; this did not increase with the longevity of the prosthesis (p = 0.54). In 59 hips showing evidence of osteolysis, the mean linear wear rate was significantly higher at 0.23 mm/year (p < 0.001). The mean linear wear rate also correlated significantly with age at the time of operation (p = 0.008), but we found no significant correlations with body-weight, gender, aetiology of the disease, thickness of polyethylene, or cup position. Our new method of measurement is time-saving and reproducible. The results confirm the greater rate of linear wear of polyethylene in patients showing osteolysis and in those who are younger

A new method for the measurement of tibial torsion using computerised transverse tomography is presented. Its accuracy is equal to that of cadaveric skeletal measurement. This method may be used in patients with unilateral post-traumatic torsional deformities, especially when these are combined with genu varum or valgum. The study of torsional aberrations in connection with congenital abnormalities of the foot is of further interest

1. The importance of accurate methods of measuring the strength of muscles and the amplitude of joint movements in man, both in clinical fields and as criteria of normal function, is discussed. 2. The advantages and disadvantages of subjective and objective methods are reviewed. 3. The main types of apparatus used for the assessment of muscle strength in both normal and clinical conditions are described. A dynamometer of the strain-gauge type is recommended. 4. Methods of measuring the amplitude of movements in man are also described. The protractor type arthrometer is thought to be the most suitable for routine clinical work, but for research purposes a radiographic method may be preferable. 5. The following factors, which must be considered if the measurements taken are to be of greatest use, are discussed: posture, test procedure, standards for comparison, nomenclature and normal variability

The angle of inclination of the acetabular component in total hip replacement is a recognised contributing factor in dislocation and early wear. During non-navigated surgery, insertion of the acetabular component has traditionally been performed at an angle of 45° relative to the sagittal plane as judged by the surgeon’s eye, the operative inclination. Typically, the method used to assess inclination is the measurement made on the postoperative anteroposterior radiograph, the radiological inclination. The aim of this study was to measure the intra-operative angle of inclination of the acetabular component on 60 consecutive patients in the lateral decubitus position when using a posterior approach during total hip replacement. This was achieved by taking intra-operative photographs of the acetabular inserter, representing the acetabular axis, and a horizontal reference. The results were compared with the post-operative radiological inclination. The mean post-operative radiological inclination was 13° greater than the photographed operative inclination, which was unexpectedly high. It appears that in the lateral decubitus position with a posterior approach, the uppermost hemipelvis adducts, thus reducing the apparent operative inclination. Surgeons using the posterior approach in lateral decubitus need to aim for a lower operative inclination than when operating with the patient supine in order to achieve an acceptable radiological inclination

The aim of this study was to define the microcirculation of the normal rotator cuff during arthroscopic surgery and investigate whether it is altered in diseased cuff tissue. Blood flow was measured intra-operatively by laser Doppler flowmetry. We investigated six different zones of each rotator cuff during the arthroscopic examination of 56 consecutive patients undergoing investigation for impingement, cuff tears or instability; there were 336 measurements overall. The mean laser Doppler flowmetry flux was significantly higher at the edges of the tear in torn cuffs (43.1, 95% confidence interval (CI) 37.8 to 48.4) compared with normal cuffs (32.8, 95% CI 27.4 to 38.1; p = 0.0089). It was significantly lower across all anatomical locations in cuffs with impingement (25.4, 95% CI 22.4 to 28.5) compared with normal cuffs (p = 0.0196), and significantly lower in cuffs with impingement compared with torn cuffs (p < 0.0001). Laser Doppler flowmetry analysis of the rotator cuff blood supply indicated a significant difference between the vascularity of the normal and the pathological rotator cuff. We were unable to demonstrate a functional hypoperfusion area or so-called ‘critical zone’ in the normal cuff. The measured flux decreases with advancing impingement, but there is a substantial increase at the edges of rotator cuff tears. This might reflect an attempt at repair

Long radiographs are used to measure lower limb axial alignment, to assess the progression of deformity, and to plan corrective surgery. The purpose of this study was to test the belief that jigs are necessary in order to control limb position for radiography. Above-knee amputated limbs were fixed in different positions of rotation and of knee flexion and radiographed to study the effect on the apparent alignment of the limb. If the limb was rotated no more than 10 degrees from the neutral the effect on apparent axial alignment was minimal and radiographic measurement was reliable. This suggests that standardised positioning jigs are not needed in routine clinical practice

We have studied the influence of weight-bearing on the measurement of wear of the polyethylene acetabular component in total hip arthroplasty using two techniques. The measured vertical wear was significantly greater when radiographs were taken weight-bearing rather than with the patient supine (p = 0.001, method 1; p = 0.007, method 2). Calculations of rates of linear wear of the acetabular component were significantly underestimated (p < 0.05) when radiographs were taken supine. There are two reasons for this. First, a change in pelvic orientation when bearing weight ensures that the thinnest polyethylene is brought into relief, and secondly, the head of the femoral component assumes the position of maximal displacement along its wear path. Interpretation of previous studies on both linear and volumetric polyethylene wear in total hip arthroplasty should be reassessed in the light of these findings

Anteversion of the femoral neck of 30 unpaired dry bones was measured directly, by ultrasound, and by computerised tomography. The angles measured directly corresponded well with the angles found by CT scan, but there was poor correlation between these and the angles measured by ultrasound. At present ultrasound seems to be unsuitable for the measurement of anteversion of the femoral neck

We describe a new method for the accurate measurement of the angle of anteversion of an acetabular cup from standard anteroposterior radiographs, and provide the conversion tables required. The effect of the centering of the radiograph is discussed and a method of distinguishing between anteversion and retroversion by using a caudally directed x-ray beam is described

The transcutaneous oxygen pressure (tcPO2) was measured by a polarographic technique in the legs of 161 volunteers and compared with the levels found in 62 patients with ischaemic skin due to peripheral vascular disease. The results show that the tcPO2 was related to the degree of ischaemia and, in many cases, was a more accurate guide to the viability of the skin than clinical assessment. Measurement of the transcutaneous oxygen pressure in the leg at the site of amputation in 24 patients with peripheral vascular disease showed that a preoperative level greater than 40 millimetres of mercury at an electrode temperature of 44 degrees Celsius was necessary for the skin of the stump to heal. The technique is simple, non-invasive and reliable. The tcPO2 accurately reflects the physiological and pathological changes in the circulation of the skin. It has potential in many fields of surgery where careful assessment of the viability of the skin is necessary

In a prospective study of the measurement of osteoporosis in patients with fracture of the femoral neck, we compared a histological with a radiological method. We found no significant correlation between histological planimetry and the radiological six metacarpal hand index in patients with either cervical or trochanteric fractures. This demonstrates that metacarpal morphometry cannot predict histological osteoporosis of the iliac crest

Accurate measurement of the alignment of the tibia is important both clinically and in research. The conventional method of measuring the angle of malunion after a fracture of the shaft of the tibia is potentially inaccurate because the mechanical axis of the normal bone may not pass down the centre of the medullary canal. An alternative method is described in which a radiograph of the opposite tibia is used as a template. A sample of 56 sets of standard radiographs of healed fractures of the shaft of the tibia was evaluated. The 95% limits of agreement between this and the conventional method were wide, being −6.2° to +5.5° for coronal angulation and −6.7° to +8.1° for sagittal angulation. These results suggest that the conventional method is inaccurate. The new method has good inter- and intraobserver reliability

We report the ten-year results for three designs of stem in 240 total hip replacements, for which subsidence had been measured on plain radiographs at regular intervals. Accurate migration patterns could be determined by the method of Einzel-Bild-Roentgen-Analyse-femoral component analysis (EBRA-FCA) for 158 hips (66%). Of these, 108 stems (68%) remained stable throughout, and five (3%) started to migrate after a median of 54 months. Initial migration of at least 1 mm was seen in 45 stems (29%) during the first two years, but these then became stable. We revised 17 stems for aseptic loosening, and 12 for other reasons. Revision for aseptic loosening could be predicted by EBRA-FCA with a sensitivity of 69%, a specificity of 80%, and an accuracy of 79% by the use of a threshold of subsidence of 1.5 mm during the first two years. Similar observations over a five-year period allowed the long-term outcome to be predicted with an accuracy of 91%. We discuss the importance of four different patterns of subsidence and confirm that the early measurement of migration by a reasonably accurate method can help to predict long-term outcome. Such methods should be used to evaluate new and modified designs of prosthesis

Many radiographic techniques have been described for measuring patellar height. They can be divided into two groups: those that relate the position of the patella to the femur (direct) and those that relate it to the tibia (indirect). This article looks at the methods that have been described, the logic behind their conception and the critical analyses that have been performed to test them.

There have been conflicting reports on the effects of gamma irradiation on the material properties of cortical allograft bone. To investigate changes which result from the method of preparation, test samples must be produced with similar mechanical properties to minimise variations other than those resulting from treatment. We describe a new method for the comparative measurement of bone strength using standard bone samples. We used 233 samples from six cadavers to study the effects of irradiation at a standard dose (28 kGy) alone and combined with deep freezing. We also investigated the effects of varying the dose from 6.8 to 60 kGy (n = 132). None of the treatments had any effect on the elastic behaviour of the samples, but there was a reduction in strength to 64% of control values (p < 0.01) after irradiation with 28 kGy. There was also a dose-dependent reduction in strength and in the ability of the samples to absorb work before failure. We suggest that irradiation may cause an alteration in the bone matrix of allograft bone, but provided it is used in situations in which loading is within its elastic region, then failure should not occur

The measurement of bone mineral density in defined areas around metal implants has improved with the development of dual-energy X-ray absorptiometry. We used this technique to compare the bone mineral density adjacent to metal cementless femoral implants with that of identical regions of bone in normal proximal femora. We studied the anteroposterior views only of 72 femora which contained total hip implants and 34 non-operated femora. We compared the regional bone mineral density of bone adjacent to proximally porous-coated and distally porous-coated implants of one design, to measure the relative differences in the remodelling changes induced by different amounts of porous coating. We also measured differences in bone density with time and with variations in implant size (and therefore stiffness). The greatest decrease in bone mineral density (34.8%) occurred in the most proximal 1 cm of the medial femoral cortex around relatively stiff, extensively porous-coated implants. The next most severe decrease (20% to 25%) was in the next most proximal 6 cm of the medial femoral cortex. Small, progressive decreases in bone mineral density continued for five to seven years after implantation

Fractures and plastic deformities of the forearm are common in children. While axial deformities are easily recognised and treated, bowing of the radius may be overlooked. Physiological bowing is essential for full rotation of the forearm. We have used the method of Schemitsch and Richards to estimate the degree of bowing in 100 children who had not suffered a fracture of the forearm.

The site of maximum bowing remained constant at 60.39% of the length of the radius (95% CI 59.65 to 61.14). The value of maximum bowing did not exceed 10% of the total length (mean value 7.21%; 95% CI 7.00 to 7.41). This study provides information that can be useful for the diagnosis of bowing and for the evaluation of post-traumatic deformities.