A comparison of 2 cementing techniques in hip resurfacing using human femoral heads.

INTRODUCTION: Hip resurfacing remains a valid option in young male patients. The creation of the optimum cement mantle aids fixation of the femoral component. If the cement mantle is too thick the prosthesis can remain proud leading to early failure or if it penetrates too far into the femoral head, it may cause osteonecrosis. METHOD: 18 of 96 femoral heads collected from patients undergoing total hip arthroplasty were matched for their surface porosity. They were randomly allocated into 2 different cementing groups. Group 1 had the traditional bolus of cement technique, while group 2 had a modified cementing technique (swirl) where the inside of the femoral component was lined with an even layer of low viscosity cement. RESULTS: The traditional bolus technique had significantly greater cement mantle thickness in 3 of 4 zones of penetration (p = 0.002), greater and larger air bubble formation (6 of 9 in bolus technique vs. 1 in 9 in swirl technique, p = 0.05) and more incomplete cement mantles compared with the swirl technique. There was no relationship to femoral head porosity. CONCLUSION: The swirl technique should be used to cement the femoral component in hip resurfacing. Long-term clinical studies would conform if this translates into increased survivorship of the femoral component.

The porosity of the bone cement interface of 96 human femoral heads prepared for hip resurfacing.

PURPOSE: The porosity of the femoral head prepared for hip resurfacing has not been previously described. This is important as greater pore size increases the penetration of bone cement and excessive cement penetration can cause osteonecrosis. METHODS: 96 osteoarthritic femoral heads were harvested at total hip arthroplasty and prepared for hip resurfacing. The porosity of the bone cement interface in hip resurfacing was calculated from digitised black and white photographs using MatLab software. RESULTS: The mean porosity was 0.63. Increased porosity was associated with larger femoral heads in both the coronal and sagittal dimensions and cysts in the femoral head. It was not associated with gender, age, body mass index (BMI), smoking, alcohol or corticosteroid consumption. CONCLUSION: The porosity of the femoral head has been shown to be 0.63. Future studies of cementing techniques in hip resurfacing should include this porosity in their designs. The surgeon prior to hip resurfacing should consider altering his cementing technique when cysts are present on the preoperative radiographs.

Reliability and Responsiveness of Patient-Reported Outcome Measures of Neck Disability to Physical Therapy: Comparison of the Copenhagen, Northwick Park, and Neck Bournemouth Questionnaires and the Neck Disability Index.

OBJECTIVE: The purpose of this study was to identify the external and internal reliability and responsiveness of the validated patient-reported outcome measures (PROMs) of neck pain to a standardized regimen of physiotherapy administered acutely after mild whiplash injury using the clinically significant improvement components of the Patient Global Impression of Change (PGIC) as the outcome measure. METHODS: Eighty-six patients with neck pain alone were referred for physiotherapy within 2 weeks of whiplash injury. They completed the Copenhagen, Northwick Park (NP), and Neck Bournemouth (NBQ) questionnaires and the Neck Disability Index (NDI) before starting and after treatment when they also completed the PGIC. Treatment comprised deep soft tissue massage, myofascial releases, muscle energy techniques, joint articulation and manipulation techniques, and a home exercise program. The duration of treatment was between 3 and 6 weeks. A PGIC of 6 or 7 was considered to be clinically significant improvement. RESULTS: The external reliability of the PROMs was >0.7 and internal >0.87. All components of the PROMs contributed to the final score except headache in the Copenhagen and upper-limb dysesthesia in the NP. The most reliable questionnaire was the NBQ, which was significantly more responsive than the Copenhagen (P = .008). The NBQ was slightly more responsive than the NDI and NP. The NBQ and NDI were successfully completed more frequently than the NP and Copenhagen. CONCLUSION: The NP, NDI, and NBQ are all reliable and responsive measures of change after physiotherapy for neck pain after acute whiplash injury.

An 18-year comparison of hybrid total hip replacement and Birmingham hip resurfacing in active young patients.

AIM: To compare the long-term clinical and radiological results of metal-on-polyethylene hybrid total hip replacement (THA) with metal-on-metal Birmingham hip resurfacing (BHR) in young, active patients. PATIENTS AND METHODS: From the 1st consecutive 63 hips in young, active patients who underwent BHR by the senior author, 54 (51 patients) were matched to patients who had undergone THA with regard to age, gender, body mass index and preoperative levels of activity. Radiologically, all hips were assessed for migration and osteolysis, THAs for polyethylene wear and BHRs for a pedestal sign. Patient-reported outcomes, mortality and revision rates were compared. RESULTS: The mean follow-up of the patients with a hybrid THR was 19.9 years and for those with a BHR, 17.6 years. 13 patients with a hybrid THR and 5 with a BHR had died. 1 hybrid THR and 3 BHRs were lost to follow-up. The revision rate of the hybrid THRs was 14/54 and of the BHRs 6/54. Log rank comparison of Kaplan-Meier survival estimates demonstrated a significantly lower mortality in the BHR group (p = 0.039; hazard ratio [HR] = 0.37 [95% CI, 0.15-0.95]) but a non-significant difference in revision rates (p = 0.067; HR = 0.43 [95% CI, 0.18-1.06]). The BHRs recorded superior OHS (p = 0.03), UCLA (p = 0.0096), and EuroQol visual analogue scores (p = 0.03). Significantly more BHRs had run, played sport and undertaken heavy manual labour in the month preceding follow-up. CONCLUSION: After 18 years, patients with BHRs remained more active with a lower mortality rate but demonstrated no significant difference in revision rates. Both groups demonstrated progressive radiological changes at long-term follow-up.

Histology of failed metal-on-metal hip arthroplasty; three distinct sub-types.

The histological specimens from 29 failed metal-on-metal (MoM) hip arthroplasties treated at our institution were reviewed. Five patients had a failed MoM total hip arthroplasty (THA), and 24 patients a failed hip resurfacing. Clinical and radiographic features of each hip were correlated with the histological findings. We report three major histological subtypes. Patients either have a macrophage response to metal debris, a lymphocytic response (ALVAL) or a mixed picture of both. In addition we observe that the ALVAL response is located deep within tissue specimens, and can occur in environments of low wear debris. The macrophage response is limited to the surface of tissue specimens, with normal underlying tissue. Patients with subsequently confirmed ALVAL underwent revision surgery sooner than patients whose histology confirms a macrophage response (3.8 vs. 6.9 years p<0.05). Both histological subtypes (ALVAL and macrophage dominant) are responsible for abnormal soft tissue swellings.

The thermal effects of lavage on 57 ox femoral heads prepared for hip resurfacing arthroplasty.

BACKGROUND AND PURPOSE: Previously, we have documented surface temperatures recorded by thermography great enough to cause osteonecrosis of the femoral head during hip resurfacing. We now performed an in vitro investigation with 3 questions: (1) whether water irrigation reduced bone surface temperature, (2) whether external bone temperatures were similar to core temperatures, and (3) whether blunting of the reamer affected temperature generation. METHODS: Using an ox-bone model, 57 femoral heads were peripherally reamed. The surface temperatures of bone were measured using a thermal camera and internal bone temperatures were measured using 2 theromocouples. We measured the effects of cooling with water at room temperature and with ice-cooled water. Progressive blunting of reamers was assessed over the 57 experiments. RESULTS: Mean and maximum temperatures generated during peripheral reaming were greater when no irrigation was used. Ice-cold saline protected femoral heads from thermal damage. External bone temperatures were much greater than internal temperatures, which were not sufficiently elevated to cause osteonecrosis regardless of lavage. Blunting of the reamer was not found to have a statistically significant effect in this study. INTERPRETATION: Cooling with ice-cooled water is recommended. Internal bone temperatures are not elevated despite the high surface temperatures reached during femoral head resurfacing.

Blood levels of cobalt and chromium are inversely correlated to head size after metal-on-metal resurfacing arthroplasty.

Resurfacing arthroplasty has fallen out of favour in recent years due to unfavourable survivorship in joint registries and alarming reports of soft tissue reactions around metal on metal prostheses. Our aim was to assess the effect of head size, implant design and component positioning on metal production by resurfacing arthroplasties. We measured whole blood cobalt and chromium and component position in matched populations implanted with two designs of resurfacing arthroplasty over a two-year period. Both implants resulted in a significant increase in blood metal levels (p<0.001) though the ASR design generated significantly higher metal levels (p = 0.041). A significant inverse correlation was seen between component size and blood cobalt levels (p = 0.032) and blood chromium levels (p<0.001). No correlation was identified between component position and blood metal levels. Small diameter metal resurfacing components result in increased metal generation compared with larger components. As increased metal generation has been correlated to wear and therefore failure, caution must be used on implantation of smaller components and indeed, in those who require smaller components, alternative bearing materials should be considered. These results contrast with recent findings which have demonstrated early failure for larger diameter stemmed metal-on-metal prostheses.

Aircast walking boot and below-knee walking cast for avulsion fractures of the base of the fifth metatarsal: a comparative cohort study.

BACKGROUND: Acute avulsion fractures of the base of the fifth metatarsal are common and are treated in a variety of ways. The aims of this study were to compare pain, functional outcome, and time taken off work after treatment with a walking boot or a short-leg cast. METHODS: Of 39 patients with acute avulsion fractures of the base of the fifth metatarsal, 23 were treated with a short-leg cast and 16 with a walking boot, according to the preference of the consultant present at outpatient clinic. Functional outcome was assessed by the Visual Analogue Scale Foot and Ankle Questionnaire (VAS FA), pain, and other complaints on presentation and at 3, 6, 9, and 12 weeks after injury. The VAS FA scores were compared between the 2 groups by a paired Student t test. RESULTS: The mean time to return to the level of pain and function before injury was approximately 9 weeks after treatment in the walking boot group and 12 weeks with a short-leg cast. Patients with walking boots reported less pain between 3 and 12 weeks than did those with short-leg casts after 6 (P = .06), 9 (P = .020), and 12 weeks (P = .33). Function was significantly better with Aircast walking boots after 3 (P = .006), 6 (P = .002), and 9 weeks (P = .002) but not after 12 weeks (P = .09). Patients returned to their preinjury level of driving after 6 weeks with walking boots and 12 weeks with short-leg casts (P = .006). Employed patients took a mean of 35.8 days off work (range, 28-42 days), fewer with boots (31.5 days) than with short-leg casts (39.2 days). CONCLUSION: The walking boot was better treatment than a short-leg cast for avulsion fractures of the base of the fifth metatarsal. Patients had an improved combined level of pain and function 3 weeks earlier, at 9 weeks post injury, when managed in a walking boot. LEVEL OF EVIDENCE: Level II, prospective comparative series.

The medium term outcome of the Omnifit constrained acetabular cup.

Recurrent dislocation requiring revision surgery occurs in approximately 4% of primary total hip arthroplasties (THAs). To reduce this risk, or to treat those patients who recurrently dislocate, a constrained acetabular component may be used, however there are concerns over the success of such components due to increased mechanical stresses. The purpose of this study was to analyse the survivorship and radiological results for the Omnifit constrained acetabular component, providing a longer patient reported outcome follow-up than previous studies. 117 patients (median age 82 years) underwent a THA with an Omnifit constrained acetabular component. Of these, 45 were primary replacements and 72 were revisions. Survivorship analysis was performed and patients were assessed both radiologically and functionally. At follow-up, 53 patients (45.3%) had died at a median time of 33 months from operation. The median overall follow-up was 7.0 (5.5-8.2) years. Survivors (median age 83 years) reported a median Oxford Hip Score (OHS) of 16.6 (0-48), 87.8% were satisfied with their surgery. 45 (91.8%) of the acetabular components were stable radiologically, 48 (96%) of the femoral components were stable (5 uncemented, 43 cemented) and two possibly unstable. Four of the 117 patients underwent further surgery. Only one required revision of the prosthesis and this was for a periprosthetic fracture. In the medium term the Omnifit constrained acetabular component prevents dislocation and does not cause excessive loosening of either the acetabular or femoral components in our patient population. Our results support the use of the Omnifit constrained acetabular component in elderly patients at risk of dislocation with low functional demand.

Enhancing proximal femoral pressure during cemented stem insertion.

BACKGROUND: Poor proximal femoral pressures during a cemented primary hip replacement may compromise proximal fixation and cause early aseptic loosening. Occlusion of the calcar, during stem insertion, achieves a uniform and sustained rise in the proximal intra-medullary pressure, which should enhance cement penetration into bone and improve long-term survival of the prosthesis. METHODS: 54 Exeter stems were cemented into femoral moulds prepared from plaster of Paris. Pressure transducers were connected to the proximal, middle and distal zones of the mould. After cement insertion, stems were implanted with occlusion of the calcar by either nothing, a thumb placed medially or an Exeter horse-collar. 18 stems each were inserted into Palacos-R at 3½-4 minutes and 4-4½ minutes after mixing and Simplex-P 6-6½ minutes after mixing and the intra-medullary pressures were measured. Data were subjected to regression analysis using SPSS. RESULTS: Proximal and distal intra-medullary pressures were significantly higher (P < 0.01-0.001) with proximal occlusion in all cements. The highest pressures were achieved with Palacos-R at 4-4½ minutes after mixing, with proximal thumb occlusion. Stem insertion into Palacos-R at 3½-4 min. or 4-4½ min. after mixing, gave higher pressures than into Simplex-P regardless of the method of occlusion. With Simplex-P, there was a trend to higher proximal intra-medullary pressures with the horse-collar. CONCLUSION: Occluding the calcar during stem insertion into cement achieves and sustains high intra-medullary pressures in both the proximal and distal femur. The highest pressures are obtained with stem insertion into Palacos-R at 4-4½ minutes after mixing, with proximal thumb occlusion. A horse-collar achieves slightly higher pressures with Simplex-P.

Does preoperative anxiety and depression predict satisfaction after total knee replacement?

BACKGROUND AND PURPOSE: Approximately one fifth of patients are not satisfied with the outcome of total knee arthroplasty (TKA). Preoperative variables associated with poorer outcomes are severity and chronicity of pain, psychological disease, poor coping strategies and pain catastrophisation. Psychological disease may be expressed as anxiety and depression. It is unclear whether anxiety and depression before TKA are constitutional or result from knee pain. The aim of this study was to explore the association of anxiety and depression with knee pain and function using specific outcome measures. METHODS: Forty consecutive patients undergoing TKA completed Hospital Anxiety and Depression Scale (HAD) and Oxford Knee Scores (OKS) preoperatively and at 3 and 6 months postoperatively. RESULTS: The HAD and OKS significantly improved post-operatively (p<0.001). There was a greater change between the preoperative and postoperative scores in the OKS than the HAD. The severity of preoperative anxiety and depression was associated with higher levels of knee disability (coefficient -0.409, p=0.009). Postoperatively reduction in anxiety and depression was associated with improvement in knee disability after 3 (coefficient -0.459, p=0.003) and 6 months (coefficient -0.428, p=0.006). INTERPRETATION: The difficulty in interpreting preoperative anxiety and depression and the outcome of TKA is establishing whether they are the cause or effect of pain in the knee. As anxiety and depression improve with knee pain and function, this study suggests that knee pain contributes to the psychological symptoms and that a successful TKA offers an excellent chance of improving both.

Maximum temperatures of 89°C recorded during the mechanical preparation of 35 femoral heads for resurfacing.

BACKGROUND AND PURPOSE: We noticed that our instruments were often too hot to touch after preparing the femoral head for resurfacing, and questioned whether the heat generated could exceed temperatures known to cause osteonecrosis. PATIENTS AND METHODS: Using an infra-red thermal imaging camera, we measured real-time femoral head temperatures during femoral head reaming in 35 patients undergoing resurfacing hip arthroplasty. 7 patients received an ASR, 8 received a Cormet, and 20 received a Birmingham resurfacing arthroplasty. RESULTS: The maximum temperature recorded was 89°C. The temperature exceeded 47°C in 28 patients and 70°C in 11. The mean duration of most stages of head preparation was less than 1 min. The mean time exceeded 1 min only on peripheral head reaming of the ASR system. At temperatures lower than 47°C, only 2 femoral heads were exposed long enough to cause osteonecrosis. The highest mean maximum temperatures recorded were 54°C when the proximal femoral head was resected with an oscillating saw and 47°C during peripheral reaming with the crown drill. The modified new Birmingham resurfacing proximal femoral head reamer substantially reduced the maximum temperatures generated. Lavage reduced temperatures to a mean of 18°C. INTERPRETATION: 11 patients were subjected to temperatures sufficient to cause osteonecrosis secondary to thermal insult, regardless of the duration of reaming. In 2 cases only, the length of reaming was long enough to induce damage at lower temperatures. Lavage and sharp instruments should reduce the risk of thermal insult during hip resurfacing.

Prevention of infection in orthopaedic joint replacement.

Infection of a prosthetic joint is a significant adverse event, affecting the patient, the surgical team, and consuming hospital resources. The patient faces multiple operations, a prolonged hospital stay and a more challenging period of rehabilitation. The surgeon must perform longer and more technically demanding revision operations in order to remove the infected prosthesis, increasing the burden on hospital resources. It has been estimated that that the cost of managing an infected total hip replacement (THR) is four times greater than for a primary procedure (Dreghorn & Hamblen 1989). The personal cost to the patient must also be emphasised.

Reducing the risk of surgical site infection: a case controlled study of contamination of theatre clothing.

Surgical site infections are one of the most important causes of healthcare associated infections (HCAI), accounting for 20% of all HCAIs. Surgical site infections affect 1% of joint replacement operations. This study was designed to assess whether theatre clothing is contaminated more inside or outside the theatre suite. Petri dishes filled with horse blood agar were pressed on theatre clothes at 0, 2, 4, 6 and 8 hours to sample bacterial contamination in 20 doctors whilst working in and outside the theatre suite. The results showed that there was greater bacterial contamination when outside the theatre suite at 2 hours. There were no differences in the amount of contamination at 4, 6 and 8 hours. This study suggests that the level of contamination of theatre clothes is similar both inside and outside the theatre setting.

A comparison of neck movement in the soft cervical collar and rigid cervical brace in healthy subjects.

OBJECTIVE: The soft cervical collar has been prescribed for whiplash injury but has been shown to be clinically ineffective. As some authors report superior results for managing whiplash injury with a cervical brace, we were interested in comparing the mechanical effectiveness of the soft collar with a rigid cervical brace. Therefore, the purpose of this study was to measure ranges of motion in subjects without neck pain using a soft cervical collar and a rigid brace compared with no orthosis. METHODS: Fifty healthy subjects (no neck or shoulder pain) aged 22 to 67 years were recruited for this study. Neck movement was measured using a cervical range of motion goniometer. Active flexion, extension, right and left lateral flexion, and right and left rotation were assessed in each subject under 3 conditions: no collar, a soft collar, and a rigid cervical brace. RESULTS: The soft collar and rigid brace reduced neck movement compared with no brace or collar, but the cervical brace was more effective at reducing motion. The soft collar reduced movement on average by 17.4%; and the cervical brace, by 62.9%. The effect of the orthoses was not affected by age, although older subjects had stiffer necks. CONCLUSION: Based on the data of the 50 subjects presented in this study, the soft cervical collar did not adequately immobilize the cervical spine.

Clinical tests for carpal tunnel syndrome in contemporary practice.

INTRODUCTION: A study conducted to establish the most accurate combination of questionnaire and physical signs for the diagnosis of carpal tunnel syndrome. METHOD: Nerve conduction studies confirmed 70 patients with having carpal tunnel syndrome who were enrolled along with 70 age- and sex-matched controls. Patients were assessed using a symptom questionnaire, Phalen's test, Hoffmann-Tinel's sign, hand elevation test, carpal compression test, tourniquet test, pressure aesthesiometry and two-point discrimination. RESULTS: Through multivariate analysis, the best combination of tests was tourniquet, carpal compression and Phalen's tests but the difference between these and hand elevation test alone was negligible. CONCLUSION: The hand elevation test may be used in isolation and is superior to questionnaires and other physical signs in the clinical diagnosis of carpal tunnel syndrome.

Anti-embolism stockings and proximal indentation.

The authors of this study noticed that the elastic garters of below knee anti-embolism stockings (AES) were indenting the proximal calves of patients after application and feared this might be interrupting venous return. This was lower on one ward which had a rigorous standardized protocol for sizing and checking stockings. Hypotheses were that proximal indentation caused higher proximal than distal pressures (reverse gradients) and that by adopting the standardized protocol throughout the unit, proximal indentation could be reduced. Fifty-seven patients were recruited after total hip replacement (THR) or total knee replacement (TKR) in a regional orthopaedic centre. The authors implemented the standardized protocol for sizing stockings and measured the pressures under them. After implementation of the standardized protocol, proximal indentation fell from 53% to 19% (p<0.05), incorrectly sized stockings from 74% to 34% (p<0.05) and removal of stockings by patients from 32% to 0% (p<0.05). In total, 21% of patients had reverse gradients which occurred in 41% of legs with proximal indentation and 8% without. When reverse gradients or proximal indentation exist, AES may not be as effective and may be counterproductive. A standardized protocol of nursing practice is critical to optimizing AES after THR and TKR. More in-vivo research is needed on AES after hip and knee replacement.

Comparison of methods of measuring active cervical range of motion.

STUDY DESIGN: Experimental study. Cervical range of motion (CROM) was measured using different clinical methods. OBJECTIVE: To compare the reliability and accuracy of visual estimation, tape measurement, and the universal goniometer (UG) with that of the CROM goniometer in measuring active CROM in healthy volunteers. The secondary objective was to identify the single neck movement that best represents overall range of motion. SUMMARY OF BACKGROUND DATA: Neck movement is affected by pathology in the spine and shoulder. A reliable and accurate measurement of neck movement is required to quantify injury, recovery, and disability. Various methods of measuring neck movement have been described of which radiography remains the accepted reference standard. However, radiography is impractical for routine clinical assessment. Visual estimation, tape measurement, and the UG are convenient alternatives. To date, the accuracy and reliability of these methods have not been compared in healthy subjects, and the single neck movement that best reflects overall range has not yet been identified. METHODS: Active cervical flexion, extension, right and left lateral flexion and rotation were measured in 100 healthy volunteers. Visual estimation, tape measurement between fixed landmarks, and the UG aligned on fixed and anatomic landmarks were compared with the CROM goniometer, which was used as the reference standard. RESULTS: Compared with the CROM goniometer, the UG aligned on fixed landmarks was the most accurate method, followed by the UG on anatomic landmarks. The reliability of the UG was between substantial and perfect. Visual estimation was reproducible but measured range of movement inaccurately. Tape measurement was inaccurate. Extension best reflected overall range. CONCLUSION: The UG aligned on a fixed landmark is most reliable method of measuring neck movement clinically. Where range must be quickly assessed, extension should be measured.

Katz and Stirrat hand diagram revisited.

Katz and Stirrat devised a hand diagram, which uses subjective information from the patient for the diagnosis of carpal tunnel syndrome (CTS). They reported a good result. We tested the inter-observer and intra-observer reliability of this hand diagram. Twenty five consecutive patients with a diagnosis of CTS, 25 with other common hand and wrist problems but CTS and 25 healthy individuals were prospectively recruited. Each patient filled in a hand diagram. Two experienced hand surgeon scored the diagrams blindly on two different sittings four-week apart. The intra-class correlation coefficient (ICC) and Cohen's Kappa were used for intra and inter-observer reliability respectively. The intra-observer agreement was poor (ICC 95% 0.33-0.65) and inter-observer was fair (Kappa = 0.241). This study does not support the use of Katz and Stirrat Hand Diagram for the diagnosis of carpal tunnel syndrome in place if a thorough clinical examination.