Aims: To study the natural history and treatment of chronic skeletal pelvic pain following childbirth. Methods: 53 patients were studied, of which 13 had surgery to the symphysis pubis (11 fusion, 2 stabilisation). A detailed history was recorded and an examination carried out. Investigations included pelvic X-rays with stress views and MRI of the symphysis pubis in a selected group. Results: Mean age at onset 30.6 years, gestation 39.3 weeks (36–42). 16 of the 17 subsequent pregnancies were associated with recurrence of symptoms. Long term disability showed no relation to type of delivery (p> 0.5). Pain was worse before menstruation. 55% of patients beneþted from conservative management. This did not relate to the site of pain (p> 0.1). Stress views of the symphysis: 39, mean vertical shift 2.2mm. There was no correlation between shift and symptoms. MRI of the symphysis:17, 6 were normal and 11 revealed non-speciþc changes. Surgery:mean age at surgery 34.8 y, time to operation 4.2 y and follow up 23.6 m. Outcome: 7 good, 6 no beneþt. There was a strong reverse correlation between disability and outcome (r=−0.84) while the site of pain had no effect on outcome (p> 0.8). Conclusions: Chronic skeletal pelvic pain following pregnancy is poorly understood and under-diagnosed. It tends to be recurrent and its onset is related to hormonal and mechanical factors in pregnancy. The type of delivery is unlikely to be important although care should be taken with leg and patient positioning. There is no relationship between shift and severity. Conservative treatment is the main standby. Surgery, on the basis of this small study, is useful in those with moderate disability but contraindicated in those with severe disability.

We hypothesise that the stiffness of the acetabular component influences the stresses transmitted to bone. Thus stress shielding or stress overload of the underlying host bone may be influenced by the choice of fixation method. In addition, we believe that the so called “brake drum effect” plays a significant role in the development of rim stresses and subsequent failure of fixation.

We have constructed a jig which allows the direct comparison, under controlled conditions, of contact stresses measured behind the acetabular component of polyethylene controls, uncemented metal backe cups and cemented all polyethylene cups, under physiological load. The design of the jig also allows measurement of stresses transmitted to the acetabular rim of the same three prostheses in order to confirm the presence and magnitude of the brake drum effect. The contact stresses are measured by miniature pressure transducers which are inserted through specially drilled holes in the shell of the jig so that the transducer is flush with the prosthesis under test. A total of 6 transducers are arranged in concentric circles radiating away from the prosthetic dome, so that contact stresses may be directly measured in various parts of the acetabular bed under conditions that reproduce as closely as possible the situation in a total hip prosthesis in vivo. Thus our method can be compared to other laboratory and theorectical techniques for investigation into stress transmission around acetabular components. The transducers were callibrated prior to each test to ensure parity of test results. The transducers were prestressed to ensure contact prior to each test. 6 polyethylene uncemented liners were tested alone in the jig to act as a control. In the same fashion, the same 6 polyethylene components were tested firstly in an uncemented, metal back acetabular component, and then as a cemented, all polyethylene component.

The results indicate that significantly less stress is transmitted to bone when metal back components are used as compared to cemented components and controls. The data confirms that the brake drum effect occurs in both cemented and uncemented prostheses, leading to at least the absence of compressive forces at the prosthetic rim and in some circumstances tensile forces.

Introduction: We hypothesise that the fixation method of the acetabular component influences stress transmission to the host bone in vivo. We believe that the frequency of appearance of radiolucent lines at the prosthetic rim is directly related to the brake drum effect whereby compressive forces at the dome of a semi-rigid body leads to tensile forces at the rim.

Method: A series of miniature pressure transducers were manufactured and positioned at the prosthetic/ bone interface of an acetabular component of a total hip arthroplasty (THA) in a jig designed to replicated the loading conditions of a THA in vivo. The transducers were arranged in a series of five concentric rings spaced from the centre of the acetabular dome to the prosthetic rim. A total of six transducers was used. Three separate experiments were performed: 1. a polyethylene component alone to act as a control. 2. a polyethylene component surrounded by a cement mantle and 3. a polyethylene component surrounded by a metal-back. A separate jig was constructed to provide a cement mantle of the same thickness as the metal back. The stress transmitted to the host bone was measured in each case.

Results: The results indicated that successively less stress was transmitted when changing from controls to cemented then to metal-backed cups. Both cemented and uncemented cups demonstrated at the very least absence of compressive forces at the prosthetic rim and in some cases tensile forces, indicating that the brake drum effect is likely.

Tissue reaction to wear particles from metal implants may play a major role in the aseptic loosening of implants. We used electron microprobe elemental analysis to determine the chemical composition of wear particles embedded in the soft tissues around hip and knee implants from 11 patients at revision surgery for aseptic loosening. The implants were made of cobalt-chromium-molybdenum alloy or titanium-aluminium-vanadium alloy. Histological examination showed a widespread giant-cell reaction to the particles. Elemental analysis showed that the chemical composition of the particles was different from that of the implanted alloys: cobalt and titanium were reduced, often down to zero, whereas chromium and aluminium persisted. Our findings indicate that corrosion is continually changing the shape, size and chemical composition of the implanted alloy. This may alter the biochemical environment of the tissue surrounding an implant to favour bone resorption.

We report the finding of sodium- and phosphorus-based crystallisation in abnormal human articular cartilage. We prepared five chondromalacic, five osteoarthritic and four macroscopically normal specimens of patellar cartilage by a cryofracturing technique and examined them in a scanning electron microscope. An energy-dispersive X-ray microanalysis system was used to identify the crystals, which were found in only three of the five chondromalacic specimens. Star-shaped crystals were seen either individually or in clusters in the matrix of the cartilage. They consisted of sodium and phosphorus, and we have found no previous reports of such findings. The calcified zone, the bone, and the articular surface were free from crystals.

In an animal model we determined the strength of anterior cruciate ligaments (ACL) after section and repair by four different methods and compared it with that of the intact ligament. The standard suturing technique of multiple loops through the ligament stumps was used. Stronger suture material did not give a stronger repair. Wrapping a fine polyester mesh around the ligament or placing it between the bundles before suture increased the strength of the repair. This modification, allied to protective rehabilitation, may reduce the failure rate of acute ACL repairs.

We performed postoperative venography on 84 consecutive patients who had undergone upper tibial osteotomy for medial compartment osteoarthritis of the knee. Deep-vein thrombosis was demonstrated in 41%. Only 15% of the cases were diagnosed clinically, all in the calf veins. Cases of proximal thromboses (3) and mixed-vein thromboses (12) were only revealed by venography.

We studied the arterial anatomy and the effect of four-part fractures on the vascularity of the humeral head, using barium sulphate perfusion of 16 cadaver shoulders. The main arterial supply to the humeral head was via the ascending branch of the anterior humeral circumflex artery and its intraosseous continuation, the arcuate artery. There were significant intraosseous anastomoses between the arcuate artery and: 1) the posterior humeral circumflex artery through vessels entering the posteromedial aspect of the proximal humerus; 2) metaphyseal vessels; and 3) the vessels of the greater and lesser tuberosities. Simulated four-part fractures prevented the perfusion of the humeral head in most cases. If, however, the head fragment extends distally below the articular surface medially, some perfusion of the head persists by the posteromedial vessels. These vessels are important in the management of comminuted fractures of the proximal humerus.

Previous perfusion studies of the rotator cuff have demonstrated an area of hypovascularity in the distal part of the supraspinatus tendon. This has been implicated in the pathogenesis of its rupture. We performed a quantitative histological analysis of the vascularity of the tendons of supraspinatus and infraspinatus. Vessel number, size and the percentage of the tendon occupied by vessels were measured at 5 mm intervals from the humeral insertions to the muscle bellies. Both tendons were hypovascular in their distal 15 mm. No significant difference was demonstrated between the vascularity of supraspinatus and infraspinatus. We conclude that factors other than vascularity are important in the pathogenesis of supraspinatus rupture.

We report the experimental use of three different biological implants to restore articular surface defects: glutaraldehyde-fixed bovine meniscal xenograft, glutaraldehyde-fixed bovine costal cartilage xenograft, and viable osteochondral allografts. The grafts were implanted in the knees of 19 goats who were allowed free-field activity and were studied for up to one year. The natural articular surfaces of meniscal fibrocartilage provided excellent articular surfaces at all times. Equally good articular surfaces were restored by host tissue growth covering costal cartilage grafts at six months, but by 12 months this surface had degenerated. The majority of the allografts survived and integrated with the host at six months, but many showed signs of failure at 12 months. Only three out of seven ungrafted defects healed completely at six months and the healed surfaces were degenerating at 12 months.

Using dried bones which could be tilted and rotated, we assessed the accuracy of published radiographic methods for measuring the migration of prosthetic acetabular components and compared the results with a new method. The new line linking acetabular margins was significantly more accurate for proximal migration than the teardrop, the sacroiliac line or the sacroiliac-symphysis line. For medial migration, a new line tangential to the brim and through the horizontal mid-point of the obturator foramen was more accurate than Kohler's line, the ilio-ischial line or the iliopubic line. In combination, the two new lines can give a more accurate assessment of acetabular erosion than previous methods, since they are less affected by the differences in rotation commonly found in a series of radiographs.

In rabbits, repair of incisions in the central part of the meniscus has been demonstrated after surgical excision of the peripheral rim. Healing took place via a highly cellular but relatively avascular fibrous tissue stroma which proliferated from the synovial margin and invaded along the cut edge of the meniscus. Suturing facilitated this healing process by providing stability and possibly by supplying bridges for synovial cells to migrate onto the meniscus. Transformation of fibrous tissue into fibrocartilage has also been observed.

Four cases of slipped upper femoral epiphyses in patients with intracranial tumours causing hypopituitarism and chiasmal compression are presented. Detailed endocrine studies in three cases showed severe deficiencies of growth hormone as well as of gonadotrophin and sex hormones. The literature is reviewed and the aetiology is discussed with special reference to Harris's hypothesis that an increase in growth hormone relative to oestrogen predisposes to slipping of the upper femoral epiphysis in humans, which these cases do not seem to support. In all cases the slip was bilateral, and it is emphasised that surgical treatment can provide only temporary fixation because fusion is dependent on correct hormonal therapy.