Internal fixation of femoral neck fractures. Compression screw compared with nail plate fixation

Surgical interventions for treating intracapsular hip fractures in older adults: a network meta-analysis

BACKGROUND

Hip fractures are a major healthcare problem, presenting a considerable challenge and burden to individuals and healthcare systems. The number of hip fractures globally is rising rapidly. The majority of intracapsular hip fractures are treated surgically.

OBJECTIVES

To assess the relative effects (benefits and harms) of all surgical treatments used in the management of intracapsular hip fractures in older adults, using a network meta-analysis of randomised trials, and to generate a hierarchy of interventions according to their outcomes.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Web of Science, and five other databases in July 2020. We also searched clinical trials databases, conference proceedings, reference lists of retrieved articles and conducted backward-citation searches.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs comparing different treatments for fragility intracapsular hip fractures in older adults. We included total hip arthroplasties (THAs), hemiarthroplasties (HAs), internal fixation, and non-operative treatments. We excluded studies of people with hip fracture with specific pathologies other than osteoporosis or resulting from high-energy trauma.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion. One review author completed data extraction which was checked by a second review author. We collected data for three outcomes at different time points: mortality and health-related quality of life (HRQoL) - both reported within 4 months, at 12 months, and after 24 months of surgery, and unplanned return to theatre (at end of study follow-up). We performed a network meta-analysis (NMA) with Stata software, using frequentist methods, and calculated the differences between treatments using risk ratios (RRs) and standardised mean differences (SMDs) and their corresponding 95% confidence intervals (CIs). We also performed direct comparisons using the same codes.

MAIN RESULTS

We included 119 studies (102 RCTS, 17 quasi-RCTs) with 17,653 participants with 17,669 intracapsular fractures in the review; 83% of fractures were displaced. The mean participant age ranged from 60 to 87 years and 73% were women.  After discussion with clinical experts, we selected 12 nodes that represented the best balance between clinical plausibility and efficiency of the networks: cemented modern unipolar HA, dynamic fixed angle plate, uncemented first-generation bipolar HA, uncemented modern bipolar HA, cemented modern bipolar HA, uncemented first-generation unipolar HA, uncemented modern unipolar HA, THA with single articulation, dual-mobility THA, pins, screws, and non-operative treatment. Seventy-five studies (with 11,855 participants) with data for at least two of these treatments contributed to the NMA. We selected cemented modern unipolar HA as a reference treatment against which other treatments were compared. This was a common treatment in the networks, providing a clinically appropriate comparison. In order to provide a concise summary of the results, we report only network estimates when there was evidence of difference between treatments. We downgraded the certainty of the evidence for serious and very serious risks of bias and when estimates included possible transitivity, particularly for internal fixation which included more undisplaced fractures. We also downgraded for incoherence, or inconsistency in indirect estimates, although this affected few estimates. Most estimates included the possibility of benefits and harms, and we downgraded the evidence for these treatments for imprecision.  We found that cemented modern unipolar HA, dynamic fixed angle plate and pins seemed to have the greatest likelihood of reducing mortality at 12 months. Overall, 23.5% of participants who received the reference treatment died within 12 months of surgery. Uncemented modern bipolar HA had higher mortality than the reference treatment (RR 1.37, 95% CI 1.02 to 1.85; derived only from indirect evidence; low-certainty evidence), and THA with single articulation also had higher mortality (network estimate RR 1.62, 95% CI 1.13 to 2.32; derived from direct evidence from 2 studies with 225 participants, and indirect evidence; very low-certainty evidence). In the remaining treatments, the certainty of the evidence ranged from low to very low, and we noted no evidence of any differences in mortality at 12 months.  We found that THA (single articulation), cemented modern bipolar HA and uncemented modern bipolar HA seemed to have the greatest likelihood of improving HRQoL at 12 months. This network was comparatively sparse compared to other outcomes and the certainty of the evidence of differences between treatments was very low. We noted no evidence of any differences in HRQoL at 12 months, although estimates were imprecise. We found that arthroplasty treatments seemed to have a greater likelihood of reducing unplanned return to theatre than internal fixation and non-operative treatment. We estimated that 4.3% of participants who received the reference treatment returned to theatre during the study follow-up. Compared to this treatment, we found low-certainty evidence that more participants returned to theatre if they were treated with a dynamic fixed angle plate (network estimate RR 4.63, 95% CI 2.94 to 7.30; from direct evidence from 1 study with 190 participants, and indirect evidence). We found very low-certainty evidence that more participants returned to theatre when treated with pins (RR 4.16, 95% CI 2.53 to 6.84; only from indirect evidence), screws (network estimate RR 5.04, 95% CI 3.25 to 7.82; from direct evidence from 2 studies with 278 participants, and indirect evidence), and non-operative treatment (RR 5.41, 95% CI 1.80 to 16.26; only from indirect evidence). There was very low-certainty evidence of a tendency for an increased risk of unplanned return to theatre for all of the arthroplasty treatments, and in particular for THA, compared with cemented modern unipolar HA, with little evidence to suggest the size of this difference varied strongly between the arthroplasty treatments.

AUTHORS' CONCLUSIONS

There was considerable variability in the ranking of each treatment such that there was no one outstanding, or subset of outstanding, superior treatments. However, cemented modern arthroplasties tended to more often yield better outcomes than alternative treatments and may be a more successful approach than internal fixation. There is no evidence of a difference between THA (single articulation) and cemented modern unipolar HA in the outcomes measured in this review. THA may be an appropriate treatment for a subset of people with intracapsular fracture but we have not explored this further.

Internal fixation implants for intracapsular hip fractures in older adults

BACKGROUND

Hip fractures are a major healthcare problem, presenting a huge challenge and burden to patients, healthcare systems and society. The increased proportion of older adults in the world population means that the absolute number of hip fractures is rising rapidly across the globe. The majority of hip fractures are treated surgically. This review evaluates evidence for types of internal fixation implants used in joint-preserving surgery for intracapsular hip fractures.

OBJECTIVES

To determine the relative effects (benefits and harms) of different implants for the internal fixation of intracapsular hip fractures in older adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Web of Science, Cochrane Database of Systematic Reviews, Epistemonikos, Proquest Dissertations and Theses, and National Technical Information Service in July 2020. We also searched clinical trials databases, conference proceedings, reference lists of retrieved articles and conducted backward-citation searches.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs comparing implants used for internal fixation of fragility intracapsular proximal femoral fractures in older adults. Types of implants were smooth pins (these include pins with fold-out hooks), screws, or fixed angle plates. We excluded studies in which all or most fractures were caused by specific pathologies other than osteoporosis or were the result of a high energy trauma.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion. One review author extracted data and assessed risk of bias which was checked by a second review author. We collected data for seven outcomes: activities of daily living (ADL), delirium, functional status, health-related quality of life (HRQoL), mobility, mortality (reported within four months of surgery as early mortality, and at 12 months since surgery), and unplanned return to theatre for treating a complication resulting directly or indirectly from the primary procedure (such as deep infection or non-union). We assessed the certainty of the evidence for these outcomes using GRADE.

MAIN RESULTS

We included 38 studies (32 RCTs, six quasi-RCTs) with 8585 participants with 8590 intracapsular fractures. The mean ages of participants in the studies ranged from 60 to 84 years; 73% were women, and 38% of fractures were undisplaced. We report here the findings of the four main comparisons, which were between different categories of implants. We downgraded the certainty of the outcomes for imprecision (when data were available from insufficient numbers of participants or the confidence interval (CI) was wide), study limitations (e.g. high or unclear risks of bias), and inconsistency (when we noted substantial levels of statistical heterogeneity). Smooth pins versus fixed angle plate (four studies, 1313 participants) We found very low-certainty evidence of little or no difference between the two implant types in independent mobility with no more than one walking stick (1 study, 112 participants), early mortality (1 study, 383 participants), mortality at 12 months (2 studies, 661 participants), and unplanned return to theatre (3 studies, 736 participants). No studies reported on ADL, delirium, functional status, or HRQoL. Screws versus fixed angle plates (11 studies, 2471 participants) We found low-certainty evidence of no clinically important differences between the two implant types in functional status using WOMAC (MD -3.18, 95% CI -6.35 to -0.01; 2 studies, 498 participants; range of scores from 0 to 96, lower values indicate better function), and HRQoL using EQ-5D (MD 0.03, 95% CI 0.00 to 0.06; 2 studies, 521 participants; range -0.654 (worst), 0 (dead), 1 (best)). We also found low-certainty evidence showing little or no difference between the two implant types in mortality at 12 months (RR 1.04, 95% CI 0.83 to 1.31; 7 studies, 1690 participants), and unplanned return to theatre (RR 1.10, 95% CI 0.95 to 1.26; 11 studies, 2321 participants). We found very low-certainty evidence of little or no difference between the two implant types in independent mobility (1 study, 70 participants), and early mortality (3 studies, 467 participants). No studies reported on ADL or delirium. Screws versus smooth pins (seven studies, 1119 participants) We found low-certainty evidence of no or little difference between the two implant types in mortality at 12 months (RR 1.07, 95% CI 0.85 to 1.35; 6 studies, 1005 participants; low-certainty evidence). We found very low-certainty evidence of little or no difference between the two implant types in early mortality (3 studies, 584 participants) and unplanned return to theatre (5 studies, 862 participants). No studies reported on ADL, delirium, functional status, HRQoL, or mobility. Screws or smooth pins versus fixed angle plates (15 studies, 3784 participants) In this comparison, we combined data from the first two comparison groups. We found low-certainty evidence of no or little difference between the two groups of implants in mortality at 12 months (RR 1.04, 95% CI.083 to 1.31; 7 studies, 1690 participants) and unplanned return to theatre (RR 1.02, 95% CI 0.88 to 1.18; 14 studies, 3057 participants). We found very low-certainty evidence of little or no difference between the two groups of implants in independent mobility (2 studies, 182 participants), and early mortality (4 studies, 850 participants). We found no additional evidence to support the findings for functional status or HRQoL as reported in 'Screws versus fixed angle plates'. No studies reported ADL or delirium.

AUTHORS' CONCLUSIONS

There is low-certainty evidence that there may be little or no difference between screws and fixed angle plates in functional status, HRQoL, mortality at 12 months, or unplanned return to theatre; and between screws and pins in mortality at 12 months. The limited and very low-certainty evidence for the outcomes for which data were available for the smooth pins versus fixed angle plates comparison, as well as the other outcomes for which data were available for the screws and fixed angle plates, and screws and pins comparisons means we have very little confidence in the estimates of effect for these outcomes. Additional RCTs would increase the certainty of the evidence. We encourage such studies to report outcomes consistent with the core outcome set for hip fracture, including long-term quality of life indicators such as ADL and mobility.

Poor citation of prior evidence in hip fracture trials

BACKGROUND

Failure to cite prior evidence in the medical literature may result in publication redundancy and inefficient use of research funding. We evaluated trials in which internal fixation was compared with arthroplasty for the treatment of hip fractures in order to determine the extent to which these randomized trials cited all relevant previous trials.

METHODS

We searched MEDLINE and Embase for all relevant articles on four topics: internal fixation compared with arthroplasty, total hip arthroplasty compared with hemiarthroplasty, sliding hip screws compared with other fixation devices, and surgical delay of hip fracture treatment. We determined the proportion of previous studies that were cited in comparison with the total number of previous studies that were citable (i.e., the citation rate) as well as the proportion of times that a study was cited in comparison with the total number of times that it could have been cited (i.e., the hit rate). A cumulative meta-analysis was performed for the "internal fixation compared with arthroplasty" topic to determine whether compelling evidence favoring one intervention existed at an earlier time.

RESULTS

In total, sixty studies were assessed and yielded an overall citation rate of 48%. All "highly cited" studies reported a positive result (favoring arthroplasty), and 60% were published in The Journal of Bone and Joint Surgery (American or British volume). The results of a study and the journal of publication significantly affected the hit rate (p < 0.05).

CONCLUSIONS

Our review of studies of hip fracture treatment suggests poor citation of the previous literature. Studies in higher-impact journals with positive results are more likely to be cited in subsequent studies. Therefore, redundancy in publication and unnecessary surgical trials often occur.

Internal fixation implants for intracapsular proximal femoral fractures in adults

BACKGROUND

Numerous different implants with screws, pins and side plates have been used for the internal fixation of intracapsular hip fractures.

OBJECTIVES

To determine from randomised trials which implant is superior for the internal fixation of intracapsular proximal femoral fractures.

SEARCH STRATEGY

We searched the Cochrane Musculoskeletal Injuries Group specialised register. The date of the most recent search was December 2000.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing different implants for the internal fixation of intracapsular hip fractures in adults.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality, by use of a ten item scale, and extracted data. Additional information was sought from trialists. After grouping by implant type, comparable groups of trials were subgrouped and where appropriate, data were pooled using the fixed effects model.

MAIN RESULTS

Twenty-seven studies involving 5269 participants (5274 fractures) were included in the study. Considerable variation in the quality of methodology between studies was found and biases due to familiarity with some of the implants were noted. None of the implants tested were found to be significantly superior for any of the outcome measures related to fracture healing complications or mortality. The sliding hip screw was found to take longer to insert and to have an increased operative blood loss compared with multiple screws or pins.

REVIEWER'S CONCLUSIONS

No clear conclusions can be made on the choice of implant for internal fixation of intracapsular fractures from the available evidence within randomised trials.

Unstable femoral neck fractures in young adults: treatment with the AO 130-degree blade plate

OBJECTIVE

To evaluate the clinical outcome of the treatment of unstable femoral neck fractures using the AO 130-degree blade plate.

DESIGN

Between 1980 and 1994, thirty-four consecutive patients younger than age fifty years with an unstable intracapsular femoral neck fracture (Garden Types III-IV) were treated with internal fixation.

SETTING

University Hospital Gasthuisberg, Leuven, Belgium.

INTERVENTION

The AO 130-degree blade plate with an antirotation, 6.5-millimeter, partially threaded cancellous lag screw was used.

RESULTS

Nineteen (63.3 percent) patients had an excellent result, seven (23.3 percent) had a good result, three (10 percent) had a fair result, and one (3.3 percent) had a poor result. Delayed union was observed in one case, and avascular necrosis was observed in two cases. Two implants perforated the subchondral bone.

CONCLUSION

Stable fixation with the AO 130-degree blade plate avoids damage to the adjacent blood supply to the femoral head and appears to guarantee a good final outcome of unstable intracapsular femoral neck fractures in young adults.

Choice of implant for internal fixation of femoral neck fractures. Meta-analysis of 25 randomised trials including 4,925 patients

We reviewed all randomised trials comparing different implants for treating intracapsular fractures of the hip and, where possible, the data were combined. 25 randomised trials were identified involving 4,925 patients. Screws appeared to be superior to pins. It was not possible to determine the optimum number or type of screws. No advantage was shown for an implant with a side-plate.

Rigid osteosynthesis decreases the late complication rate after femoral neck fracture. The influence of three different osteosynthesis devices evaluated in 369 patients

The influence of three different fixation devices on late healing complications after femoral neck fractures was studied in a large patient group from three different hospitals. Except for the choice of device, which was unique to each hospital, all other factors having a potential influence on the late outcome, such as sex and age of the patients, initial degree of fracture dislocation and quality of surgical reduction were similar among the three groups. Within a 2-year observation period the incidence of late segmental collapses (14%-19%) was not related to choice of device, but a higher number of non-unions (27%-30%) occurred after adaptive non-rigid methods using screws (von Bahr) or a flanged nail (Rydell) than after a more rigid osteosynthesis (8%, Deyerle). Using such a rigid fixation, the complication rate could be reduced by one-third and the need for revision surgery halved. A device providing stable fixation should be preferred for treatment of femoral neck fractures in the elderly to prevent the healing complications related to insufficient stabilization.

Acetabular penetration of sliding screw

Case report of disengagement of sliding screw from the plate and penetration through the acetabulum into the pelvic cavity. The mechanism was probably technical failure in combination with osteoporosis and a new trauma in the region. We find that it is possible to remove the screw through the old incision, but the patient should be prepared for laparotomy.

Intracapsular fractures of the femoral neck in young patients

The details of the aetiology, treatment and outcome of acute intracapsular fractures for 58 fractures in 57 patients aged less than 60 years, were prospectively studied. The majority of the injuries were sustained by low energy trauma. Eighty-four per cent united uneventfully. There was a non-union rate of 7 per cent, and avascular necrosis rate of 10 per cent. Better results were obtained from closed than open reduction. The results do not support the commonly held view that this injury carries a poor prognosis in young patients.

An algorithm for assessment of fracture displacement and pin positions in femoral neck fractures

A method for determination of both the displacement of the femoral head and the position of the fixation device in fixed femoral neck fractures is described. In routine AP and lateral radiographs of the hip, measurements are made of femoral neck-shaft angle, the diameter of the femoral head and neck, the distances from the center of the femoral head to the femoral neck axis and the distances from the femoral neck axis to the fixating screws. From these values the position of the femoral head and the fixating screws are determined by geometric calculations. A computer program in Q-BASIC was devised to perform the calculations and to produce graphic displays of cross-sections of the femoral head and neck, with the displacement of the head and the screw positions indicated. The accuracy of the method was evaluated by a new method using axial radiographs of hip specimens, which were compared with the computer-plotted graphs of the femoral head and neck. The mean error of the method was found to be +/- 5% of the femoral head diameter, approximately 2.5 mm.

Predictive value of early scintimetry in intracapsular hip fractures. A prospective study with regard to femoral head necrosis, delayed union and non-union

In 84 patients with an intracapsular hip fracture, early technetium-99m methylene diphosphonate (99mTc-MDP) scintimetry could be carried out preoperatively of in the case of conservative treatments within 72 h after injury. Fifty-four patients were available for a 3-year follow-up. The corrected uptake ratio showed a very high accuracy in predicting secondary dislocation, non-union (NU), delayed union (DU) or femoral head necrosis (FHN) and was far more reliable than the uncorrected uptake ratio. The predictive value of scintimetric follow-up at a 2- or 12-week interval could not reach the same accuracy of early scintimetry in predicting poor outcome. A comparison of follow-up scintimetry after conservative treatment and osteosynthesis showed that the major vascular injury to the femoral head is caused at the moment of the initial trauma and that no additional damage occurs perioperatively with closed reduction and fixation with a Dynamic Hip Screw device. Scintimetry is a useful tool in predicting poor outcome due to FHN and/or NU in the treatment of intracapsular hip fractures.

Internal fixation of femoral neck fractures. Dynamic Hip and Gouffon screws compared in 73 patients

A prospective, randomized study comparing the Dynamic Hip screws and the Gouffon screws in the treatment of femoral neck fractures was terminated before the planned number of patients had been admitted, owing to a preponderance of early failure of the Gouffon screws (P 0.014); thus only 73 patients entered the study. After three years' follow-up, 25/38 Gouffon screws and 12/35 Dynamic Hip screws had failed. Six patients treated with Gouffon screws and 14 treated with Dynamic Hip screws had died. The outcome still favoured the use of Dynamic Hip screws (P 0.02).

Fixation of femoral neck fractures. A four-flanged nail versus threaded pins in 200 cases

Two methods of internal fixation for cervical hip fractures were compared in a "randomized to surgeons" type of study. One hundred patients were treated with the Rydell four-flanged nail and 100 with the Gouffon pins. Redisplacement, nonunion, or segmental collapse occurred in 27 patients operated on with the Rydell nail and in 29 patients operated on with the Gouffon pins. According to the actuarial method of follow-up, the failure rates after 2 years were 31 and 33 percent in the two groups.

Internal fixation of 410 cervical hip fractures. A randomized comparison of a single nail versus two hook-pins

Totally, 410 patients with a cervical hip fracture were randomized between two methods of osteosynthesis: a single nail (Rydell) and two hook-pins (LIH). Seventy-five percent of the patients were women. Sixty-nine percent were alive after 2 years. The patients were followed up with clinical and radiographic examinations for 2 years postoperatively. No difference between the two groups were found regarding quality of reduction, early displacement within 3 months, extraction after healing, nonunion, late segmental collapse, or reoperation with a total hip arthroplasty. Nor did we find any differences between the two groups when selecting those alive after 2 years or when dividing the fractures in displaced and nondisplaced fractures.

Fixation of femoral neck fracture. Prospective comparison of von Bahr screws, Gouffon screws, and Hessel pins

We report a prospective study of 214 patients with femoral neck fractures operated on with multiple pinning. The fractures were randomly allocated to fixation with either von Bahr screws or Hessel pins in 1983 and 1984 or von Bahr or Gouffon screws in 1984 and 1985. After 2 years, the failure rate was one third in the von Bahr and the Gouffon screw groups and one half in the Hessel pin group. We conclude that the nonthreaded Hessel pin is inferior to the von Bahr and Gouffon screws for fixation of femoral neck fractures.

Stability of femoral neck fractures. A postoperative roentgen stereophotogrammetric analysis

Using roentgen stereophotogrammetric analysis, the postoperative stability of femoral neck fractures was measured in 16 patients. During the first day after internal fixation, before weight bearing, the center of the femoral head moved on an average 1.5 mm (total translation) in six undisplaced fractures and 3.7 mm in 10 displaced fractures, which was about one third of the fracture movement during the first postoperative month. Three undisplaced fractures displayed a rotatory instability, mainly after weight bearing had begun. Five of the displaced fractures showed maximal rotatory displacement during the first postoperative day. The recorded fracture movements before weight bearing may question the rationale of peroperative mechanical compression.

Internal fixation of femoral neck fracture. No difference between the Rydell four-flanged nail and Gouffon's pins

Two methods of internal fixation of femoral neck fractures were compared in a prospective randomized study of 223 patients. Radiographic evidence of early redisplacement, nonunion, or late segmental collapse occurred in 45 of 122 patients operated on with the Rydell four-flanged hook nail and in 33 of 101 patients operated on with Gouffon pins. According to the actuarial method of follow-up, the failure rates after 2 years were respectively 41 and 35 percent in the nail and pin groups, which is a nonsignificant difference.

Fixation of displaced femoral neck fractures. A comparison between sliding screw plate and four cancellous bone screws

In a prospective, randomized trial, 104 consecutive patients with displaced femoral neck fractures were allocated either to fixation with a sliding screw plate or 4 ASIF cancellous bone screws. The patients were reexamined at fixed intervals to determine the time of union. The 2-year-cumulated rate of union was 64 per cent in the plate group and 84 per cent in the screw group.

Sequential scintimetry after femoral neck fracture. Methodologic aspects and prediction of healing complications

Forty-five patients with recent cervical hip fractures were included in a prospective, clinical, radiographic and sequential scintimetric study. Striking changes in radionuclide uptake over the entire hip region on the fracture side were found during the first 5 postoperative months. Fractures that healed without complications showed the highest relative femoral head uptake at 1 week and a peak value at 6 weeks, followed by a gradual decline at the subsequent examinations. Fractures with complications (redisplacement, nonunion, or late segmental collapse) showed a lower initial uptake and a more gradual increase and only a slight tendency towards increased uptake after 3 months. The accuracy in predicting nonunion with scintimetric examination alone is high both at 1 and at 6 weeks, and the accuracy is almost equally high with combined scintimetric, radiographic, and clinical assessment 3-5 months postoperatively.

Stability of fixation in femoral neck fractures. Comparison of four fixation devices in vivo and in cadavers

On human cadaveric femora, internal fixation of cervical osteotomies was performed with four different devices. With the use of a lever, a static force was applied through the acetabulum to the osteotomy site. Motion at the osteotomy site was measured by two strain gauges. The compression force necessary to inhibit motion at the osteotomy site during the fixation procedure was measured. This force was lower with a hook pin than with the other devices. During surgery in 12 patients with displaced femoral neck fractures, the forces holding the fracture surfaces together were measured with a dynamometer. The force at which widening of the fracture gap was observed by fluoroscopy was recorded. In seven fractures, the mean compression force was 110 (60-170) N. The remaining five fractures did not open up when pressures of up to 200 N were applied. These forces were always greater than the hook pin forces measured in the cadaver experiments, but often less than the forces obtained with the other devices.

Avascular femoral head necrosis following fracture fixation

A prospective, randomized trial of 104 consecutive patients with displaced fractures of the femoral neck treated with either a sliding screw plate or four AO cancellous bone screws was performed to study the influence of the fixation device and the fixation procedure on the vascularity of the femoral head. The vitality of the femoral head was determined by 99mTc-MDP scintigraphy performed 2-3 months after the operation. Eighty-seven patients (84 per cent) were available for assessment. The two treatment groups were comparable with regard to age, degree of primary displacement and quality of reduction. There were significantly more (P less than 0.01) avascular femoral heads or femoral heads with reduced vascularity in the sliding screw plate group (14/40, 35 per cent) than in the four AO cancellous bone screw group (5/47, 11 per cent).