The approach to total hip arthroplasty (THA) should allow adequate visualization and access so as to implant in optimal position whilst minimizing muscle injury, maintaining or restoring normal soft tissue anatomy and biomechanics and encouraging a rapid recovery with minimal complications. Every surgeon who performs primary hip arthroplasties will expound the particular virtues of his or her particular routine surgical approach. Usually this approach will be the one to which the surgeon was most widely exposed to during residency training.

There is a strong drive from patients, industry, surgeon marketing campaigns, and the media to perform THA through smaller incisions with quicker recoveries. The perceived advantage of the anterior approach is the lack of disturbance of the soft tissues surrounding the hip joint, less pain, faster recovery with the potential for earlier return to work, shorter hospital stay and improved cosmetic results. The potential disadvantages include less visibility, longer operation time, nerve injuries, femoral fractures, malposition and a long learning curve for the surgeon (and his / her patients).

The anterior approach was first performed in Paris, by Robert Judet in 1947. The advantages of the anterior approach for THA are several. First, the hip is an anterior joint, closer to the skin anterior than posterior. Second, the approach follows the anatomic interval between the zones of innervation of the superior and inferior gluteal nerves lateral and the femoral nerve medial. Third, the approach exposes the hip without detachment of muscle from the bone.

The mini-incision variation of this exposure was developed by Joel Matta in 1996. He rethought his approach to THA and his goals were: lower risk of dislocation, enhanced recovery, and increased accuracy of hip prosthesis placement and leg length equality. This approach preserves posterior structures that are important for preventing dislocation while preserving important muscle attachments to the greater trochanter. The lack of disturbance of the gluteus minimus and gluteus medius insertions facilitates gait recovery and rehabilitation, while the posterior rotators and capsule provide active and passive stability and account for immediate stability of the hip and a low risk of dislocation.

A disadvantage of the approach is the fact that a special operating table with traction is required. Potential complications include intraoperative femoral and ankle fractures. These can be avoided through careful manipulation of the limb. If a femoral fracture occurs, the incision can be extended distally by lengthening the skin incision downward along the anterolateral aspect of the thigh, and splitting the interval between the rectus femoris and the vastus lateralis.

The choice of approach used to perform a primary THA remains controversial. The primary goals are pain relief, functional recovery and implant longevity performed with a safe and reproducible approach without complications. The anterior approach is promising in terms of hospital stay and functional recovery. Although recent studies suggest that component placement in minimally invasive surgery is safe and reliable, no long-term results have been published. Further follow-up and development is necessary to compare the results with the posterior approach as most of the positive data is based on comparisons with the anterolateral approach.

The proposed benefits of the anterior approach are not supported by the current available literature. The issues regarding the difficult learning curve, rate of complications, operative time, requirement for trauma tables and image intensifier should be taken into account by surgeons starting with the anterior approach in THA.

Approximately 20% of patients undergoing primary unilateral total knee arthroplasty complain of severe pain in the contralateral knee, and 10% of patients who have had a primary total knee (TKA) undergo contralateral surgery within 1 year.

The number of patients suitable for primary TKA is rising, and so is the need for simultaneous bilateral TKA (BTKA) procedures. The advantages of single-stage BTKA include its low complication rates, high patient satisfaction, and cost-effectiveness. Others believe that there is increased morbidity and mortality.

The goal of reducing the exposure to repeated anaesthesia, total hospitalization and recovery time, and cost, while maintaining patient safety, is a laudable one. Our data suggest that bilateral TKA patients have a lower total operating time, use less pain medication, have a shorter hospital stay and lower overall treatment costs.

The cohort of patients selected for bilateral surgery in our unit is younger and has fewer comorbidities than unilateral controls. They have a high satisfaction rate and no increase in complication or readmission rates. We have seen a higher blood transfusion rate but no increase in cardiac, thromboembolic or septic complications.

The key to BTKA is patient selection and the implementation of efficient care and surgical pathways that includes a thorough pre-assessment, careful education and well-resourced aggressive post-operative physiotherapy. When appropriately applied, the benefits include a shorter overall recovery time and an accelerated return to everyday life and work.

The infected joint arthroplasty continues to be a very challenging problem. Its management remains expensive, and places an increasing burden on health care systems. It also leads to a long and difficult course for the patient, and frequently a suboptimal functional outcome. The choice of a particular treatment program will be influenced by a number of factors. These include the acuteness or chronicity of the infection; the infecting organism(s), its antibiotic sensitivity profile and its ability to manufacture glycocalyx; the health of the patient; the fixation of the prosthesis; the available bone stock; and the particular philosophy and training of the surgeon.

For most patients, antibiotics alone are not an acceptable method of treatment, and surgery is necessary. The standard of care for established infection is two-stage revision with antibiotic loaded cement during the interval period and parental antibiotic therapy for six weeks. Single stage revision may have economic and functional advantages however. We have devised a protocol that dictates the type of revision to be undertaken based on host, organism and local factors.

Our protocol has included single stage revision using antibiotic loaded cement in both THA and TKA. This was only undertaken when sensitive organisms were identified pre-operatively by aspiration and appropriate antibiotics were available to use in cement. Patients with immunocompromise, multiple infecting organisms or recurrent infection were excluded. Patients with extensive bone loss that required allograft reconstruction or where a cementless femoral component was necessary were also excluded.

Our algorithm was validated first in the hip and extended to infected TKA in 2004. This protocol has now been applied in over 100 TKA revisions for infection between 2004 and 2009. Our single stage revision rate is now over 25%. We continue to see a lower reinfection rate in these carefully selected patients, with high rates of infection control and satisfaction and better functional and quality of life scores than our two-stage revision cases.

Whilst our indications are arbitrary and not based on specific biomarkers, we present excellent results for selective single stage exchange. A minimum three-year follow-up suggests that these patients have shorter hospital stays, higher satisfaction rates and better knee scores. An ongoing evaluation is in place. One-stage revision arthroplasty for infection offers potential clinical and economic advantages in selected patients.

The approach to total hip arthroplasty (THA) should allow adequate visualization and access so as to implant in optimal position whilst minimizing muscle injury, maintaining or restoring normal soft tissue anatomy and biomechanics and encouraging a rapid recovery with minimal complications. The direct anterior approach (DAA) for THA was first performed in Paris, by Robert Judet in 1947. This procedure has since been performed consistently by a small group of surgeons and has recently gained great popularity. Access to the hip can be safely performed with one or two assistants. The advantages of the anterior approach for hip arthroplasty are several. First, the hip is an anterior joint, closer to the skin anterior than posterior. Second, the approach follows the anatomic interval between the zones of innervation of the superior and inferior gluteal nerves lateral and the femoral nerve medial. Third, the approach exposes the hip without detachment of muscle from the bone. Care must be taken to avoid cutting the lateral femoral cutaneous nerve which runs over the fascia of the sartorius. The mini-incision variation of this exposure was developed by Joel Matta in 1996. He rethought his approach to hip arthroplasty and by abandoning the posterior approach and adopting the anterior approach his goals were: lower risk of dislocation, enhanced recovery, and increased accuracy of hip prosthesis placement and leg length equality. This approach preserves posterior structures that are important for preventing dislocation while preserving important muscle attachments to the greater trochanter. The lack of disturbance of the gluteus minimus and gluteus medius insertions facilitates gait recovery and rehabilitation while the posterior rotators and capsule provides active and passive stability and accounts for immediate stability of the hip and a low risk of dislocation. Using the anterior approach, patients are allowed to mobilise their hip freely. The gluteus maximus and tensor fascia latae muscles insert on the iliotibial band which joins them and form a ´hip deltoid´. Lack of disturbance of these abductors and pelvic stabilisers is another benefit of the anterior approach and accelerates gait recovery. The lateral femoral cutaneous nerve is at risk when the fascia is incised between the tensor fascia latae and the sartorius muscle. Damaging it may lead to a diminished sensation on the lateral aspect of the thigh and formation of a neuroma.

A disadvantage of the approach is the fact that a special operating table with traction is required. Potential complications include intra-operative femoral and ankle fractures. These can be avoided through careful manipulation of the limb. If a femoral fracture occurs, the incision can be extended distally along the anterolateral aspect of the thigh, and splitting the interval between the rectus femoris and the vastus lateralis. In obese or muscular patients, where visibility is in doubt, an increase of the incision length will give the surgeon the required view.

The choice of approach used to perform a primary THA remains controversial. The primary goal of a hip replacement is pain relief, functional recovery and implant longevity performed with a safe and reproducible approach without complications. The anterior approach is promising in terms of hospital stay and functional recovery. Although recent studies suggest that component placement in minimally invasive surgery is safe and reliable, no long-term results have been published. Further follow-up and development is necessary to compare the results with the posterior approach. The proposed benefits of with the DAA are not supported by the current available literature. The issues regarding the difficult learning curve, rate of complications, operative time, requirement for trauma tables and image intensifier should be taken into account by surgeons starting with the DAA in THA.

Introduction

Acetabular revision surgery is becoming more prevalent with an estimated increase of 137% by 2030. It is challenging surgery especially in the presence of deficient bone loss. Several techniques of acetabular reconstruction are used world-wide. The greater the bone loss (Paprosky Type IIIA and IIIB, and AAOS Classification of Acetabular Bone Loss Type 3 and 4) the more complex are the reconstruction methods. There is however, insufficient literature comparing the contemporary techniques of revision acetabular reconstruction and their outcomes.

The best surgical modality for treating chronic periprosthetic shoulder infections has not been established, with a lack of randomised comparative studies. This systematic review compares the infection eradication rate and functional outcomes after single- or two-stage shoulder exchange arthroplasty, to permanent spacer implant or resection arthroplasty.

Full-text papers and those with an abstract in English published from January 2000 to June 2014, identified through international databases, were reviewed. Those reporting the success rate of infection eradication after a single-stage exchange, two-stage exchange, resection arthroplasty or permanent spacer implant were included, with a minimum follow-up of 6 months and sample size of 5 patients.

Eight original articles reporting the results after resection arthroplasty (n = 83), 6 on single-stage exchange (n = 75), 13 on two-stage exchange (n = 142) and 8 papers on permanent spacer (n = 68) were included.

The average infection eradication rate was 86.7% at a mean follow-up of 39.8 months (SD 20.8) after resection arthroplasty, 94.7% at 46.8 months (SD 17.6) after a single-stage exchange, 90.8% at 37.9 months (SD 12.8) after two-stage exchange, and 95.6% at 31.0 months (SD 9.8) following a permanent spacer implant. The difference was not statistically significant.

Regarding functional outcome, patients treated with single-stage exchange had statistically significant better postoperative Constant scores (mean 51, SD 13) than patients undergoing a two-stage exchange (mean 44, SD 9), resection arthroplasty (mean 32, SD 7) or a permanent spacer implant (mean 31, SD 9) (p=0.029). However, when considering studies comparing pre- and post-operative Constant scores, the difference was not statistically significant.

This systematic review failed to demonstrate a clear difference in infection eradication and functional improvement between all four treatment modalities for established periprosthetic shoulder infection. The relatively low number of patients and the methodological limitations of the studies available point out the need for well designed multi-center trials to further assess the best treatment option of peri-prosthetic shoulder infection.

Introduction

Recent studies on large diameter femoral head hip replacements have implicated the modular taper junction as one of the significant sources of wear and corrosion products and this has been attributed to increased torque and bending on the taper interface. The aim of this study was to assess the effect of frictional torque and bending moment on fretting corrosion at the taper junction and to investigate whether different material combinations also had an effect.

Total knee replacement (TKR) is considered the “gold standard” treatment for advanced osteoarthritis (OA) of the knee with good survivorship and functional outcomes. However up to 20% of patients undergoing TKR may have unicompartmental disease only. Treatment options for medial compartment arthritis can include both unicompartmental knee replacements (UKR) and TKR. While some surgeons favor TKR with a proven track record, others prefer UKR due to more normal joint kinematics, better proprioception and better motion. There is also a higher rate of return to sports amongst patients with UKR compared to TKR.

When considering all knee procedures, partial knee replacements account for 7–9%, primary TKRs for 83–88%, and revision knee replacements for 5–8%. Unicompartmental Knee Replacements comprise more than 90% of all partial knee replacement procedures. Proponents of UKR cite as advantages the preservation of normal knee kinematics, lower peri-operative morbidity, blood loss and infection risk compared with TKRs, as well as accelerated patient rehabilitation and recovery. However, partial knee replacements have a higher rate of revision than TKRs. This may be partly because they are inserted in patients with higher expectations, and partly because they are easier to revise. As a result, the volume of UKRs implanted has diminished over time and continues to decline.

We compared patient reported outcomes, satisfaction and perception of normality of the knee post-operatively between UKR and TKR. A single unit and single surgeon series of patients were recruited. Data was collated for 68 well-matched patients with more than 24 months follow-up. UKR was undertaken in patients with isolated medial compartment osteoarthritis; stable ACL and less than grade 3 lateral patellar changes of the Outerbridge classification. TKR was undertaken for the rest. The patients were assessed with validated knee scores including the Total Knee Function Questionnaire (TKFQ) which focuses on recreational and sporting outcomes as well as activities of daily living (ADL). Patient satisfaction and perception of knee normality was measured on a visual analogue scale.

Thirty-four patients with a TKR and 34 patients with a UKR were analyzed. The average ages in the TKR and UKR groups were 69.25 and 67.26 years, respectively. The patients were well-matched for demographics and had equivalent pre-operative morbidities and scores. The UKR group had better WOMAC (p=0.003), SF36 (physical: p<0.001 mental: p=0.25), Oxford knee (p<0.001) and Knee Society scores (p=0.002, function: p<0.001). The UKR group showed better outcomes in the TKFQ including exercise and sport (p= 0.02), movement and lifestyle (p=0.02) and the ADL (p=0.002). There was, however, no difference in patient satisfaction scores (p=0.41) and perception of how normal the knee felt between the two groups (p=0.99).

A UKR procedure confers better functional outcome in terms of recreation and sport compared to TKR procedures. While UKR is an appropriate choice in the elderly yet active patient with unicompartmental knee arthritis, satisfaction is similar to that of patients with a TKR reflecting higher pre-operative expectations. We believe that in appropriate centers, the UKR procedure is associated with excellent outcomes. UKR should have a secure place in the knee arthroplasty armamentarium provided current knowledge regarding patient selection and surgical technique is followed.

Introduction

The reconstructive hip surgeon is commonly faced with complex cases where severe bone loss makes conventional revision techniques difficult or impossible. This problem is likely to increase in future, as there is a good correlation between the degree of bone loss seen and number of previous total hip operations. In such situations, one alternative is the use impaction allografting with cement. This has captured the attention of the orthopaedic community because of its potential for reconstituting femoral bone stock.

Introduction

Hip and groin injuries are common in athletes participating in high level sports. Adductor muscle tendon injuries represent a small but important number of these injuries. Avulsion injuries involving tendons attaching to the symphysis pubis have previously been described and can be managed both operatively and non-operatively.

The aim is to describe a rare variant of this injury; complete avulsion of the adductor sleeve complex including adductor longus, pectineus and rectus abdominus. A surgical technique is then outlined which promotes a full return to pre-injury level of sporting activity.

A multitude of different bearing combinations exist to recreate the artificial hip joint. To date, there is no particular ‘gold-standard’ total hip arthroplasty (THA) couple since none is faultless. Strategies to improve performance are aimed either at modifying the shape and design of components or their material properties. Wear particle generation is now well recognised as a cause of aseptic loosening which consistently features amongst the most common indication for revision THA and thus minimising wear lies at the cornerstone of developing bearing couples. However, history has shown the use of supposed newer and improved materials have not been without occasional catastrophic failure. Hard-on-hard bearings are theoretically more resistant to wear but component fracture and squeaking has been witnessed with ceramic-on-ceramic articulations whilst metal-on-metal articulations have been plagued by reports of pseudotumor and ALVAL formation. This has all led to resurgence in the hard-on-soft couple.

More recently, corrosion at taper junctions has been identified as a significant factor in hip arthroplasty failure. Femoral head materials, surface changes or coatings may therefore have an increasing role to play.

In 2005, a multi-center, prospective, assessor and patient-blinded, randomised control trial was initiated. This was designed as a three armed study with either cobalt-chrome or oxidized zirconium femoral heads articulating against highly cross-linked polyethylene (XLPE) liners and oxidized zirconium articulating against ultra-high molecular weight polyethylene (UHMWPE). Early reports that XLPE was significantly superior to UHMWPE when coupled with cobalt-chrome meant no patient involved in the study was approved to receive a couple of cobalt-chrome and UHMWPE since it was deemed to be a high wear group.

We hypothesised that oxidized zirconium femoral heads would produce less linear wear than cobalt- chrome femoral heads at mid-term evaluation, whilst maintain similar outcomes when recording WOMAC, SF-36 and pain scores, and complication rates. All three groups were statistically comparable preoperatively and at five years when measuring normalised WOMAC, SF-36 and pain scale scores; all groups showed a statistically significant improvement in scores from baseline compared to at five years (p<0.001).

There was no significant difference in mean femoral head penetration when either oxidized zirconium or cobalt-chrome where articulated with XLPE (p=0.1533) but a significant difference in mean femoral head penetration was observed between the group that had used UHMWPE and both the other groups which had used XLPE (p<0.001). There were no hips in which either acetabular or femoral osteolysis was observed.

We have demonstrated that oxidized zirconium femoral heads are safe with low rates of wear when coupled with XLPE. However at five year follow-up, it appears that the choice of material of the acetabular bearing is more important than the choice of femoral head bearing. Further follow-up is needed in order to see if femoral head choice leads to a difference in outcome beyond 5 years as laboratory data suggests. Moreover the potential reduction of corrosion with ceramic or oxidized zirconium heads may yet also prove to be significant.

It is likely that current and future data will lead us away from the use cobalt chrome heads towards alternatives that are less likely to be associated with corrosion or wear and osteolysis.

Introduction:

The reconstructive hip surgeon is commonly faced with complex cases where severe bone loss makes conventional revision techniques difficult or impossible. This problem is likely to increase in future, as there is a good correlation between the degree of bone loss seen and number of previous total hip operations. In such situations, one alternative is the use of impaction allografting with cement.

The advantages of modularity in both primary and revision hip surgery are well documented, and have been at the heart of innovation in hip implant design over the last two decades. There have been significant developments in modularity proximally at the head-neck junction, more distally with modular necks and at mid-stem level, notable for complex revisions. Modularity allows us to address version, length and offset issues and to restore optimal hip biomechanics. There are, however, increasing clinical concerns associated with the failure of taper junctions. The use of large femoral heads and modular stems are now considered major risk factors for taper corrosion. Recent studies have shown an 8–9% early revision rate of one modular neck design due to pain and adverse local tissue reaction. I will summarise our laboratory and retrieval data on taper design and tribology in order to put in perspective the clinical use of modularity in hip arthroplasty.

Modular junctions rely on a frictional interlock. The engagement obtained and resulting micromotion is strongly influenced by taper size, taper length/engagement, material, surface finish, neck length and offset. In our quest for thinner femoral necks, greater offsets and bigger femoral heads, we have inadvertently created an environment that can generate fretting corrosion at modular junctions and leads to premature implant failure.

Our work demonstrates that increasing torque and bending moment leads to increased susceptibility to fretting corrosion at the modular taper interface of total hip replacements. This is particularly relevant with the increasing use of larger diameter femoral heads that produce higher torques. It also identifies surface area and surface finish as important factors in wear and corrosion at the modular interface of total hip replacements. Critically, the combination of these factors can lead to extensive corrosion at the interface.

Surgical technique is also important. Higher impaction loads on clean, dry surfaces result in greater contact length and extraction forces, which may influence micromotion.

It is critical in future that all innovation is introduced in a systematic gradual fashion so that we do not fall into similar traps again. The unintended consequences of minor changes in design may have a massive effect on outcomes. Our findings suggest that it may be possible to continue to employ the advantages of modularity in hip surgery whilst avoiding some of the pitfalls that have led to the failure of some modular systems.

Understanding the key design and surgical factors that drive the performance of taper junctions is vital for the surgical community. There is a body of knowledge that supports appropriate taper use / modularity to help surgeons deal with complex situations. We must be careful not throw the baby out with the bathwater.

Summary Statement

Proximal femoral bony deficits present a surgical and biomechanical challenge to implant longevity in revision hip arthroplasty. This work finds comparable primary stability when a distally fixing tapered fluted stem was compared with a conical design in cadaveric tests.

Introduction

The reconstructive hip surgeon is commonly faced with complex cases where severe bone loss makes conventional revision techniques difficult or impossible. This problem is likely to increase in future, as there is a good correlation between the degree of bone loss seen and number of previous total hip operations. In such situations, one alternative is the use impaction allografting with cement. This has captured the attention of the orthopaedic community because of its potential for reconstituting femoral bone stock.

The infected joint arthroplasty continues to be a very challenging problem. Its management remains expensive, and places an increasing burden on health care systems. It also leads to a long and difficult course for the patient, and frequently a suboptimal functional outcome. The choice of a particular treatment program will be influenced by a number of factors. These include the acuteness or chronicity of the infection; the infecting organism(s), its antibiotic sensitivity profile and its ability to manufacture glycocalyx; the health of the patient; the fixation of the prosthesis; the available bone stock; and the particular philosophy and training of the surgeon.

For most patients, antibiotics alone are not an acceptable method of treatment, and surgery is necessary. The standard of care for established infection is two-stage revision with antibiotic-loaded cement during the interval period and parental antibiotic therapy for six weeks. Single-stage revision may have economic and functional advantages however. We have devised a protocol that dictates the type of revision to be undertaken based on host, organism and local factors.

Our protocol has included single-stage revision using antibiotic-loaded cement in both THA and TKA. This was only undertaken when sensitive organisms were identified pre-operatively by aspiration and appropriate antibiotics were available to use in cement. Patients with immunocompromise, multiple infecting organisms or recurrent infection were excluded. Patients with extensive bone loss that required allograft reconstruction or where a cementless femoral component was necessary were also excluded.

Our algorithm was validated first in the hip and extended to infected TKA in 2004. This protocol has now been applied in over 100 TKA revisions for infection between 2004 and 2009. Our single-stage revision rate is now over 25%. We continue to see a lower reinfection rate in these carefully selected patients, with high rates of infection control and satisfaction and better functional and quality of life scores than our two-stage revision cases.

Whilst our indications are arbitrary and not based on specific biomarkers, we present excellent results for selective single-stage exchange. A minimum three-year follow up suggests that these patients have shorter hospital stays, higher satisfaction rates and better knee scores. An ongoing evaluation is in place. One-stage revision arthroplasty for infection offers potential clinical and economic advantages in selected patients.

The advantages of modularity in both primary and revision hip surgery are well documented, and have been at the heart of innovation in hip implant design over the last two decades. Modularity allows us to address version, length and offset issues and to restore optimal hip biomechanics. There are, however, increasing clinical concerns associated with the failure of taper junctions. The use of large femoral heads and modular stems are now considered major risk factors for taper corrosion. I will summarise our laboratory and retrieval data on taper design and tribology in order to put in perspective the clinical use of modularity in hip arthroplasty.

Modular junctions rely on a frictional interlock. The engagement obtained and resulting micromotion is strongly influenced by taper size, taper length/engagement, material, surface finish, neck length and offset. In our quest for thinner femoral necks, greater offsets and bigger femoral heads, we have inadvertently created an environment that can generate fretting corrosion at modular junctions and leads to premature implant failure.

An inverted hip replacement setup was used similar to the specified ASTM test (ASTM F1875–98). Twenty-eight millimeter Cobalt Chrome (CoCr) femoral heads were coupled with either full length (standard) or reduced length (mini) 12/14 Titanium (Ti) stem tapers. These Ti stem tapers had either a rough or smooth surface finish whilst all the head tapers had a smooth finish. Wear and corrosion of taper surfaces were compared following a 10 million loading cycle. The surface roughness parameters on the head taper were significantly increased when the head-stem contact area was reduced. Similarly, the surface roughness parameters on the head taper were significantly increased when rough stem tapers were used. With rough male tapers the CoCr head taper became circumferentially ridged with distinct areas of pitting corrosion similar to that seen on some retrievals. In these tests similar surface morphology to that on retrieved femoral heads was seen on the female head taper.

Thirty-six millimeter CoCr femoral heads were also coupled with either a CoCr or Ti stem with 12/14 tapers all with smooth finish. Increasing perpendicular horizontal offsets in the sagittal plane created incremental increases in torque. A proportional relationship between torque and corrosion was observed for both CoCr-CoCr and CoCr-Ti material combinations.

In-vitro studies were used to evaluate the role of: taper size, angle mismatch, surface finish, and manufacturing tolerances on taper engagement. In-vitro loading analysis was performed to determine the bearing friction experienced by the taper connection. The component materials analysed were CoCr and Ti for stem design and CoCr/CoCr, ceramicized metal/CoCr, and CoCr/Ti for head/neck tapers. The high performance combinations included tapers with larger diameters, rougher surface finish, tighter tolerances and a proximal locking location. Loading studies demonstrate a 15 – 31% reduction in frictional torque (for 28, 36 and 40mm head sizes) using the ceramicized metal/XLPE couples compared to CoCr/XLPE couples.

Retrieval studies were conducted to assess taper corrosion using the Goldberg system and SEM analysis. Two hundred-nine taper surfaces, with in-vivo time varying from 1 week and 10 years, were analysed showing that ceramicized metal femoral heads have a lower corrosion score compared to CoCr femoral heads.

Understanding the key design and surgical factors that drive the performance of taper junctions is vital for the surgical community. There is a body of knowledge that supports appropriate taper use / modularity to help surgeons deal with complex situations. We must be careful not throw the baby out with the bathwater.

The infected joint arthroplasty continues to be a very challenging problem. Its management remains expensive, and places an increasing burden on health care systems. It also leads to a long and difficult course for the patient, and frequently a sub optimal functional outcome. The choice of a particular treatment program will be influenced by a number of factors. These include the acuteness or chronicity of the infection; the infecting organism(s), its antibiotic sensitivity profile and its ability to manufacture glycocalyx; the health of the patient; the fixation of the prosthesis; the available bone stock; and the particular philosophy and training of the surgeon.

For most patients, antibiotics alone are not an acceptable method of treatment, and surgery is necessary. The standard of care for established infection is two stage revision with antibiotic loaded cement during the interval period and parental antibiotic therapy for six weeks. Single stage revision may have economic and functional advantages however. We have devised a protocol that dictates the type of revision to be undertaken based on host, organism and local factors.

Our protocol has included single stage revision using antibiotic loaded cement in both THA and TKA. This was only undertaken when sensitive organisms were identified preoperatively by aspiration and appropriate antibiotics were available to use in cement. Patients with immunocompromise, multiple infecting organisms or recurrent infection were excluded. Patients with extensive bone loss that required allograft reconstruction or where a cementless femoral component was necessary were also excluded.

Our algorithm was validated first in the knee and extended to infected TKA in 2004. This protocol has now been applied in over 100 TKA revisions for infection between 2004 and 2009. Our single stage revision rate is now over 25%. We continue to see a lower reinfection rate in these carefully selected patients, with high rates of infection control and satisfaction and better functional and quality of life scores than our two stage revision cases.

Whilst our indications are arbitrary and not based on specific biomarkers, we present excellent results for selective single stage exchange. A minimum three year follow-up suggests that these patients have shorter hospital stays, higher satisfaction rates and better knee scores. An ongoing evaluation is in place. One stage revision arthroplasty for infection offers potential clinical and economic advantages in selected patients.

The reconstructive hip surgeon is commonly faced with complex cases where severe bone loss makes conventional revision techniques difficult or impossible. This problem is likely to increase in future, as there is a good correlation between the degree of bone loss seen and number of previous total hip operations. In such situations, one alternative is the use impaction allografting with cement. This has captured the attention of the orthopaedic community because of its potential for reconstituting femoral bone stock.

The first clinical reports of impaction allografting on the femoral side were in relation to revision with cementless stems. The use of morsellised bone with cement on the femoral side was first reported by the Exeter group. The great enthusiasm with which this technique has been received is related to its biological potential to increase bone stock. The rapid revascularisation, incorporation and remodelling of morsellised compacted cancellous allograft differs dramatically from structural allografting where bone ingrowth usually is limited to 2–3mm. Histological evidence for bony reconstitution has been presented from postmortem retrievals, and from biopsies at the time of trochanteric wire removal.

The size of the bone chips used as morsellised allograft is important. The graft behaves as a friable aggregate and its resistance to complex forces depends on grading, normal load and compaction. It is recommended that particles of 3–5mm in diameter make up the bulk of the graft. A bone slurry, such as that produced by blunted bone mills, or by the use of acetabular reamers or high speed burrs would not give satisfactory stability. A wide range of particle sizes is recommended in order to achieve the greatest stability. Future considerations will include the potential for either adding biomaterials to the allograft, or ultimately substituting it completely.

A satisfactory cement mantle is required to ensure the longevity of any cemented stem. The primary determinant of cement mantle thickness is the differential between the graft impactors and the final stem. All femoral impaction systems require careful design to achieve a cement mantle that is uninterrupted in its length and adequate in its thickness.

The technique of impaction allografting on the femoral side was first and most successfully reported using a highly polished stem with a double tapered geometry and no collar. It is thought to be ideal for this technique as it can subside within the cement mantle, thus generating hoop stresses on the cement which creeps, potentially maintaining physiological loads on the supporting bone. The extension of this technique to other stems has led to some controversy. Confounding factors such as surgical technique, the impaction system available, the type and size of allograft bone used, and the extent of the pre-operative bone loss, will undoubtedly continue to influence such comparisons. It appears that the exact stem configuration may not be as critical as its surface finish, the amount of graft impaction possible and the cement mantle produced.

Impaction allografting is the only technique currently available that reverses the loss of bone stock seen in a revision hip arthroplasty. Moreover, this technique does not sacrifice host tissue, and could facilitate further surgery. Impaction allografting, performed with great attention to detail using appropriate equipment, represents an exciting reconstructive solution for contained femoral defects. Its role in larger and combined defects remains open to scrutiny. Careful observation and cautious optimism are necessary as further refinements may well improve the predictability of the clinical results and expand the indications for this important addition to the armamentarium of the revision surgeon.

Periprosthetic fractures in total hip arthroplasty lead to considerable morbidity in terms of loss of component fixation, loss of bone and subsequent functional deficits. We face an epidemic of periprosthetic fractures as the number of cementless implants inserted continues to rise and as the number of revisions continues to increase. The management of periprosthetic fractures requires careful preoperative imaging, planning and templating, the availability of the necessary expertise and equipment, and knowledge of the potential pitfalls so that these can be avoided both intra-operatively and in follow-up. There is a danger that these cases fall between the expertise of the trauma surgeon and that of the revision arthroplasty surgeon.

The past decade has afforded us clear treatment algorithms based on fracture location, component fixation and the available bone stock. We still nevertheless face the enduring challenge of an elderly population with a high level of comorbidity who struggle to rehabilitate after such injuries. Perioperative optimisation is critical as we have seen prolonged hospital stays, high rates of systemic complications and a significant short term mortality in this cohort.

We have also been presented with new difficult fracture patterns around anatomic cementless stems and in relation to tapered cemented and cementless stems. In many cases, fixation techniques are biomechanically and biologically doomed to fail and intramedullary stability, achieved through complex revision is required.

The treatment of unstable peri-prosthetic femur fractures can be technically challenging due to the weak non-supportive bone stock. We have seen an increase in the frequency of Type B3 fractures that require complex reconstruction with modular tapers, interlocking implants and proximal femoral replacements. Our reconstructive practice has evolved; the aims of femoral reconstruction include rotational and axial stability of the stem, near normal hip biomechanics and preserving as much femoral bone as possible. The advent of modular prostheses that gain distal fixation but have proximal options has extended the scope of this type of fixation. We now favor modular tapered stems that afford us the opportunity to reconstruct such femora whilst attempting to preserve the proximal bone. In effect, distal cone or taper fixation provides the initial stability required for the procedure to be successful but the proximal modular implant subsequently load shares to decrease stress shielding, distribute stress more evenly through the femur and minimise the risk of stem fracture. Such systems provide the intraoperative versatility that these cases require. The use of interlocking stems with coated ingrowth surfaces offers a relatively appealing solution for some complex fractures and avoids the complications that would be associated with unstable fixation or resection of the proximal femur.

Periprosthetic acetabular fractures are also increasingly recognised. This is in part due to the popularity of press fit components, which increase fracture risk both at the time of insertion and later due to medial wall stress shielding and pelvic osteolysis, and partly due to the increasing frequency of severe defects encountered at the time of revision surgery. These can present a very difficult reconstructive challenge and may require porous metal, cup-cage or custom reconstruction.

Periprosthetic fractures continue to cause problems worldwide. The sequelae of periprosthetic fractures include the financial cost of fixation or revision surgery, the associated morbidity and mortality in an elderly frail population, the difficulty with mobilisation if the patient cannot fully weight bear and a poor functional outcome in a proportion of cases. The battle over which patients or fractures require fixation and which require revision surgery continues.