An uncemented hemispherical acetabular component is the mainstay of acetabular revision and gives excellent long-term results.

Occasionally, the degree of acetabular bone loss means that a hemispherical component will be unstable when sited in the correct anatomical location or there is minimal bleeding host bone left for biological fixation. On these occasions an alternative method of reconstruction has to be used.

A major column structural allograft has been shown to restore the deficient bone stock to some degree, but it needs to be off-loaded with a reconstruction cage to prevent collapse of the graft. The use of porous metal augments is a promising method of overcoming some of the problems associated with structural allograft. If the defect is large, the augment needs to be protected by a cage to allow ingrowth to occur. Cup-cage reconstruction is an effective method of treating chronic pelvic discontinuity and large contained or uncontained bone defects.

This paper presents the indications, surgical techniques and outcomes of various methods which use acetabular reconstruction cages for revision total hip arthroplasty.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):73–7.

The purpose of this study was to identify factors that predict implant cut-out after cephalomedullary nailing of intertrochanteric and subtrochanteric hip fractures, and to test the significance of calcar referenced tip-apex distance (CalTAD) as a predictor for cut-out.

We retrospectively reviewed 170 consecutive fractures that had undergone cephalomedullary nailing. Of these, 77 met the inclusion criteria of a non-pathological fracture with a minimum of 80 days radiological follow-up (mean 408 days; 81 days to 4.9 years). The overall cut-out rate was 13% (10/77).

The significant parameters in the univariate analysis were tip-apex distance (TAD) (p <  0.001), CalTAD (p = 0.001), cervical angle difference (p = 0.004), and lag screw placement in the anteroposterior (AP) view (Parker’s ratio index) (p = 0.003). Non-significant parameters were age (p = 0.325), gender (p = 1.000), fracture side (p = 0.507), fracture type (AO classification) (p = 0.381), Singh Osteoporosis Index (p = 0.575), lag screw placement in the lateral view (p = 0.123), and reduction quality (modified Baumgaertner’s method) (p = 0.575). In the multivariate analysis, CalTAD was the only significant measurement (p = 0.001). CalTAD had almost perfect inter-observer reliability (interclass correlation coefficient (ICC) 0.901).

Our data provide the first reported clinical evidence that CalTAD is a predictor of cut-out. The finding of CalTAD as the only significant parameter in the multivariate analysis, along with the univariate significance of Parker’s ratio index in the AP view, suggest that inferior placement of the lag screw is preferable to reduce the rate of cut-out.

Cite this article: Bone Joint J 2014; 96-B:1029–34.

We report the use of porous metal acetabular revision shells in the treatment of contained bone loss. The outcomes of 53 patients with ≤ 50% acetabular bleeding host bone contact were compared with a control group of 49 patients with > 50% to 85% bleeding host bone contact. All patients were treated with the same type of trabecular metal acetabular revision shell. The mean age at revision was 62.4 years (42 to 80) and the mean follow-up of both groups was 72.4 months (60 to 102). Clinical, radiological and functional outcomes were assessed. There were four (7.5%) mechanical failures in the ≤ 50% host bone contact group and no failures in the > 50% host bone contact group (p = 0.068). Out of both groups combined there were four infections (3.9%) and five recurrent dislocations (4.9%) with a stable acetabular component construct that were revised to a constrained liner. Given the complexity of the reconstructive challenge, porous metal revision acetabular shells show acceptable failure rates at five to ten years’ follow-up in the setting of significant contained bone defects. This favourable outcome might be due to the improved initial stability achieved by a high coefficient of friction between the acetabular implant and the host bone, and the high porosity, which affords good bone ingrowth.

Purpose: The purpose of this study was to relate the extent of reaming to bone formation occurring around a critical sized defect in the tibia.

Method: Eleven canines were allocated into 2 groups: empty (N=5) or iliac crest autograft (N=6). All tibiae were reamed to 7.0 mm and fixed with a 6.5 mm statically locked intramedullary nail after creation of an 8.0 mm diaphyseal defect. The extent of reaming of the canal was dependent on the cross-sectional area of the tibia as all tibiae were reamed to 7.0 mm. Fluorescent markers were given at different times: calcein green (6 weeks), xylenol orange (9 weeks), and tetracycline (11 and 14 weeks). Animals were sacrificed at 15 weeks and perfused with a barium compound. Radiography, Micro CT, brightfield microscopy and fluorescent microscopy were used for analysis.

Results: Bone and vasculature volume within the defect were reported as a percentage of the total volume of the defect. Linear regression analysis of percent bone volume (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.925 (p=0.025) for the empty group and 0.244 (p=0.641) for the autograft group. Linear regression analysis of percent vasculature volume (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.784 (p=0.117) for the empty group and −0.146 (p=0.783) for the autograft group. Bone formation at osteotomy sites was defined as the distance from the original osteotomy site to the tip of newly formed bone. Linear regression analysis of bone formation at the osteotomy sites (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.132 (p=0.832) for the empty group and −0.937 (p=0.006) for the autograft group. Bone formation rates were reported as the distance between the fluorescent labels. Bone formation rate was less within the endosteum, cortex and periosteum with extensive reaming in empty samples.

Conclusion: Our results suggest that the acute management of tibia fractures with bone defects should involve limited reaming. This does not apply when the defect is autografted. Limited reaming may be defined by the cross-sectional area of the tibia in ratio to that of the reamer.

Purpose: The aim of our study was to evaluate bone formation and angiogenesis produced within a biodegradable poly-D, L-lactide-co-glycolide acid/calcium phosphate (PLGA/CaP) scaffold when used to treat a diaphyseal tibia defect and compare this to an iliac crest autograft or an empty defect.

Method: An 8.0 mm diaphyseal defect was created in a canine tibia model. All tibiae were reamed to 7.0 mm and fixed with a 6.5 mm statically locked intramedullary nail. Eighteen canines were allotted into three treatment groups:

empty (N=5),

Fluorescent markers were given at different times: calcein green (six weeks), xylenol orange (nine weeks), and tetracycline (11 and 14 weeks). Animals were sacrificed at 15 weeks and perfused with a barium compound. Radiography, Micro CT, and brightfield and fluorescent microscopy were used for analysis.

Results: Micro CT and brightfield images of scaffold samples displayed multiple vessels (10 to 100μm) within the scaffold. The bone volume and vasculature volume (measured with Micro CT) within the tibial defect site were reported as a percentage of the total volume of the defect site. The percent bone volume within the defect site was not different between treatment groups (p=0.112). There was greater percent vasculature volume in the scaffold group than the autograft group (p< 0.001). Bone formation at the osteotomy sites was defined as the distance from the original osteotomy site to the tip of newly formed bone. Osteotomy bone formation was significantly greater in the scaffold group than the autograft group (p=0.015). Osteotomy sites associated with greater angiogenesis displayed greater bone formation. Bone formation rates were reported as the distance between the fluorescent bone labels. Autograft samples had the greatest bone formation rates within the periosteum. Autograft and scaffold samples had the greatest rate of bone formation within the cortex.

Conclusion: Our canine tibial defect model provides a satisfactory facsimile of the traumatic tibia fracture with associated bone loss. The PLGA/CaP biodegradable scaffold we have employed promotes angiogenesis within a defect and could be used in conjunction with autografting.

We conducted a systematic review and meta-analysis of randomised controlled trials comparing cross-linked with conventional polyethylene liners for total hip replacement in order to determine whether these liners reduce rates of wear, radiological evidence of osteolysis and the need for revision. The MEDLINE, EMBASE and COCHRANE databases were searched from their inception to May 2010 for all trials involving the use of cross-linked polyethylene in total hip replacement. Eligibility for inclusion in the review included the random allocation of treatments, the use of cross-linked and conventional polyethylene, and radiological wear as an outcome measure. The pooled mean differences were calculated for bedding-in, linear wear rate, three-dimensional linear wear rate, volumetric wear rate and total linear wear. Pooled risk ratios were calculated for radiological osteolysis and revision hip replacement. A search of the literature identified 194 potential studies, of which 12 met the inclusion criteria. All reported a significant reduction in radiological wear for cross-linked polyethylene.

The pooled mean differences for linear rate of wear, three-dimensional linear rate of wear, volumetric wear rate and total linear wear were all significantly reduced for cross-linked polyethylene. The risk ratio for radiological osteolysis was 0.40 (95% confidence interval 0.27 to 0.58; I² = 0%), favouring cross-linked polyethylene. The follow-up was not long enough to show a difference in the need for revision surgery.