The selection of a prophylaxis agent is a balance between efficacy and safety. Total knee arthroplasty patients receive DVT prophylaxis because orthopaedic surgeons are concerned about the morbidity and mortality associated with pulmonary embolism. However, at the same time there is great concern about excessive bleeding. The goal is to provide the appropriate anticoagulation to prevent symptomatic pulmonary embolism (PE) and DVT but at the same time avoid over anticoagulation which can be associated with bleeding and other wound problems. Therefore, risk stratification is necessary.

Although risk stratification is the ideal way to determine the appropriate prophylaxis agent to use for a specific patient, there is no validated risk stratification strategy available today. There is general agreement at this time that patients who have had a prior PE or symptomatic DVT are at higher risk for development of a pulmonary embolism. In addition, there is a general belief that patients who have coagulation abnormalities (i.e. Factor V Leiden, Protein C and S deficiency) have an increased risk of developing a pulmonary embolism. Other factors that have been mentioned as associated with PE after total hip arthroplasty include age, female gender, and higher body mass index. The selection of a prophylaxis regimen should be influenced by the ability to mobilise the patient after surgery.

Management of symptomatic osteonecrosis of the hip includes either some type of head preservation procedure or a total hip arthroplasty (THA). In general, once there is collapse of the femoral head, femoral head preservation procedures have limited success. There are a number of different femoral head preservation procedures that are presently performed and there is no consensus regarding which one is most effective. These procedures involve a core decompression with some type of vascularised or nonvascularised grafting of the femoral head. Core decompression with bone grafting of the femoral head with stem cells harvested from the iliac crest and vascularised fibula grafts are the two most popular femoral head preservation procedures.

Once the femoral head has collapsed then a THA should be performed when the patient has significant disability. In the past, total hip arthroplasty in osteonecrosis patients was not considered a highly successful procedure because it was performed in younger patients (most patients are younger than fifty years of age) and longevity was limited by wear and osteolysis. The advent of reliable cementless acetabular and femoral fixation and alternative bearing surfaces (i.e. highly crosslinked polyethylene liners) has been associated with improved outcomes and enhanced longevity. THA is considered the procedure of choice even for young patients (less than 30 years old) with collapse of the femoral head and significant pain and disability.

There are a number of different non-operative management options for patients with a painful knee secondary to osteoarthritis (OA). In 2013 the American Academy of Orthopaedic Surgeons developed an evidence-based clinical practice guideline addressing treatment of osteoarthritis of the knee. Strength of recommendations were designated as strong, moderate and inconclusive. Strong recommendations included: self-management program, NSAIDs or tramadol and no acupuncture, no glucosamine and chondroitin sulfate and no hyaluronic acid. The “No” recommendations for hyaluronic acid and glucosamine and chondroitin sulfate were quite controversial because orthopaedic surgeons argued that some of their patients benefited from these treatments. Moderate strength recommendations included weight loss, lateral wedge insoles and needle lavage. The evidence-based data was inconclusive with respect to valgus force unloading brace, manual physical therapy, acetaminophen, opioids and pain patches. The effectiveness of corticosteroid and platelet rich plasma (PRP) injections were also inconclusive.

Unloader braces are available to decrease pressure on the involved compartment. There is data showing that these braces can be effective for some patients. However, there are concerns with patient compliance because of poor fit and discomfort. These braces seemed to be tolerated best when used for sports activities in patients with medial compartment arthritis.

Oral anti-inflammatory agents are effective in relieving pain and are a good first line agent for patients with OA. There is significant interest in the use of PRP injections for management of patients with knee OA particularly when patients have already received a steroid and/or a hyaluronic acid injection. To date there are no appropriately powered multi-centered randomised trials demonstrating that PRP is effective in decreasing pain and function in knee OA. However, there are some studies that suggest PRP can be helpful for patients with OA. Further studies to determine the indications for PRP injections are necessary. PRP injections are not covered by insurance in the United States.

In summary, the management of patients with painful OA of the knee needs to be individualised based on patient symptoms and expectations. Non-operative management can be effective in limiting pain and enhancing function.

Drainage from the knee wound after TKA is an obvious concern for the arthroplasty surgeon. One of the inherent problems with a total knee arthroplasty is there is a focus on obtaining maximum range of motion but at the same time the wound needs to heal in a timely fashion. Consistent knee drainage after a TKA is a source of concern. The quantity and quality of drainage needs to be assessed and there are certain questions that need to be answered including: 1) Is there bloody drainage which suggests fascial dehiscence?; 2) Is the patient too active?; 3) Is the drainage in some way related to DVT prophylaxis?; 4) Is the patient obese and could the drainage be secondary to fat necrosis or seroma? and 5) Is the drainage suggestive of an infection? The work-up can include C-reactive protein and sed rate, and possibly a knee aspiration. In general, C-reactive protein >100mg/L within the first six weeks after surgery suggests the presence of an infection. The sed rate is generally not useful in the early post-operative period. In the first six weeks after surgery if the number of white cells in the aspiration is >10,000 this suggests infection especially if there are 80–90% polymorphonuclear cells.

Each day of prolonged wound drainage is noted to increase the risk of infection by 29%. Morbid obesity has been shown to be an independent risk factor for infection. Some anticoagulants (i.e. low molecular weight heparin) have been associated with increased wound drainage. In a retrospective review of 11,785 total joint arthroplasties, 2.9% of joints developed wound drainage, and of these patients, 28% required further surgery. It was noted that patients that were malnourished had a 35% failure rate with respect to controlling the drainage and preventing infection versus 5% in patients that were healthy.

The International Consensus Conference on Infection concluded that a wound that has been persistently draining for greater than 5–7 days requires surgical intervention. The available literature provides little guidance regarding the specifics of this procedure. In general, if the wound is draining or is red, rest the leg for a day or two. In some instances a bulky Jones dressing can be helpful. If the drainage persists one could consider using a negative pressure dressing (wound vac) but there is little data on efficacy after TKA. If there is persistent drainage or cellulitis, then operative intervention is probably necessary. Evaluation of CRP and a knee joint aspiration can be helpful. The decision to return to the OR should be made within the first 7 days after the surgery. At the time of the procedure one will need to decide to perform either a superficial washout versus a washout and polyethylene exchange.

An outpatient total hip arthroplasty (THA) will be defined as a THA performed at an ambulatory care facility where the patient is discharged the same day as the procedure. Such procedures are being done in the United States and the hypothesis is that a “same day” THA will lead to reduced costs and improved outcomes. However, there are no appropriately powered randomised controlled trials evaluating outcomes in this group of patients to support this hypothesis.

It appears that a “same day” THA is here to stay. Therefore, the selection criteria for patients that undergo the procedure needs to be carefully defined. The safety of this regimen needs to be confirmed.

In an evaluation of the NSQIP database, Otero et al. compared outcomes in patients discharged on POD 0 and POD 1 and noted that THA patients in the POD 0 group had increased rates of complications. Risk factors for complications included age >70, smoking, COPD, CAD and hematocrit less than 36. In addition, the patients discharged on POD 0 had higher rates of diabetes, steroid use and lower hematocrit. Clearly, the selection criteria for this procedure needs to be defined.

In two separate studies, Goyal et al. and Dorr et al. noted that approximately 25% of patients were unable to leave the hospital on POD 0 usually because of nausea and/or hypertension.

Issues to consider before developing a same day discharge program include: 1) Is the patient healthy enough to go home the same day as the surgery?; 2) Does the patient live close enough to the hospital to be discharged the same day?; 3) Can the family provide the appropriate care for the patient at home?; 4) Is it really better for the patient or just better for the surgeon?

If a surgeon embarks on a same day discharge program, rigorous selection criteria must be instituted and followed. In addition, the patient must have free choice with respect to a same day discharge versus a 24-hour stay.

Wear and osteolysis are the major problems limiting the longevity of total hip arthroplasty. There is general agreement that if left untreated osteolysis will eventually lead to loosening of the acetabular component. In many cases polyethylene liner exchange may be preferable to revision of a well-fixed acetabular component. If there is osteolysis present the question is when should the polyethylene liner exchange be performed? The answer to that question has not been definitively defined at the present time.

There are few studies available that evaluate the timing of surgical intervention when acetabular osteolysis is present. Indications for surgical intervention include prevention of complete wear of the head through the polyethylene liner (liner thickness < 1.5 mm) and when the osteolysis involves 50% or more of the shell circumference on AP or lateral x-rays. Of course persistent pain with wear or osteolysis is another indication for surgery. Contraindications to cup retention and liner exchange include: 1) Malpositioned component; 2) Non-modular component; 3) Unable to obtain hip stability; 4) Thin polyethylene liner (relative); 5) Severe damage to acetabular shell; and 6) Poor track record of the acetabular component.

If one decides to retain the component the following steps are generally involved in operative management. Remove the liner and assess component stability. Assess the locking mechanism for the polyethylene. If the locking mechanism is not intact one can consider cementing the liner in place. In general, it is recommended to debride and bone graft the osteolytic lesion. The author prefers to use an access hole at the periphery of the component or at times a trapdoor can be made in the ilium. It is essential not to de-stabilise the acetabular component. At the present time there is no optimal graft material to use. Potential graft options include demineralised bone matrix or cancellous bone chips. Since dislocation is the number one complication after polyethylene liner exchange, it is a good idea to use a larger femoral head whenever possible. In some cases it is also worthwhile to consider bracing the patient after the surgery.

It is essential to be ready to perform a complete revision. Therefore, when planning to perform a polyethylene liner exchange one needs to have the appropriate components available to completely revise the acetabular component.

Drainage from the knee wound after TKA is an obvious concern for the arthroplasty surgeon. One of the inherent problems with a total knee arthroplasty is there is a focus on obtaining maximum range of motion but at the same time the wound needs to heal in a timely fashion. Consistent knee drainage after a TKA is a source of concern. The quantity and quality of drainage needs to be assessed and there are certain questions that need to be answered including: 1) Is there bloody drainage which suggests fascial dehiscence?; 2) Is the patient too active?; 3) Is the drainage in some way related to DVT prophylaxis?; 4) Is the patient obese and could the drainage be secondary to fat necrosis or seroma? and 5) Is the drainage suggestive of an infection? The work up can include C-reactive protein and sed rate, and possibly a knee aspiration. In general, C-reactive protein >100 mg/L within the first six weeks after surgery suggests the presence of an infection. The sed rate is generally not useful in the early post-operative period. In the first six weeks after surgery if the number of white cells in the aspiration is >10,000 this suggests infection especially if there are 80–90% polymorphonuclear cells.

Each day of prolonged wound drainage is noted to increase the risk of infection by 29%. Morbid obesity has been shown to be an independent risk factor for infection. Some anticoagulants (i.e. low molecular weight heparin) have been associated with increased wound drainage. In a retrospective review of 11,785 total joint arthroplasties, 2.9% of joints developed wound drainage, and of these patients, 28% required further surgery. It was noted that patients that were malnourished had a 35% failure rate with respect to controlling the drainage and preventing infection versus 5% in patients that were healthy.

The International Consensus Conference on Infection concluded that a wound that has been persistently draining for greater than 5–7 days requires surgical intervention. The available literature provides little guidance regarding the specifics of this procedure. In general, if the wound is draining or is red, rest the leg for a day or two. In some instances a bulky Jones dressing can be helpful. If there is persistent drainage or cellulitis, then operative intervention is probably necessary. Evaluation of CRP and a knee joint aspiration can be helpful. The decision to return to the OR should be made within the first 7 days after the surgery. At the time of the procedure one will need to decide to perform either a superficial washout versus a washout and polyethylene exchange.

Metal-on-metal bearing surfaces were used frequently until recently because of the potential for decreased wear and the ability to use large femoral heads which can reduce instability. However, data reported in the Australian registry over the past 5 years demonstrated an increase in failure rates compared to metal-on-polyethylene bearings. In addition, adverse local tissue reactions (ALTR) associated with pseudotumors and destruction of the soft tissue around the joint have led to revision of these implants. Unfortunately, at the present time there is no optimal management strategy that has been delineated for metal-on-metal implants because of a lack of evidence. The biologic response to metal-on-metal implants is usually local but may be systemic. The management of these patients is complex because patients may have pseudotumors and/or elevated metal ion levels and be asymptomatic. In addition, there are a number of intrinsic causes (loosening, infection, iliopsoas tendinitis) and extrinsic causes (spinal disease, trochanteric bursitis) that can be a source of pain.

There is no evidenced based approach to manage these patients and no single test should be used to determine treatment. A thorough clinical evaluation is essential and blood tests are necessary to rule out infection. Imaging studies including plain radiographs and a MARS MRI are needed to evaluate either the stability of the prosthesis and to assess for the presence of pseudotumors and soft tissue destruction around the implant. Patients with symptomatic hips and evidence of muscle involvement on MRI require revision. Finally, the clinician must always be aware of the potential for systemic effects which require early and aggressive intervention to limit the adverse response to the metal and the metal bearing.

Metal on metal bearing surfaces were used frequently until recently because of the potential for decreased wear and the ability to use large femoral heads which can reduce instability. However, data reported in the Australian registry over the past 5 years demonstrated an increase in failure rates compared to metal on polyethylene bearings. In addition, adverse local tissue reactions (ALTR) associated with pseudotumors and destruction of the soft tissue around the joint have led to revision of these implants.

Unfortunately, at the present time there is no optimal management strategy that has been delineated for metal on metal implants because of a lack of evidence. The biologic response to metal on metal implants is usually local but may be systemic. The management of these patients is complex because patients may have pseudotumors and/or elevated metal ion levels and be asymptomatic. In addition, there are a number of intrinsic causes (loosening, infection, iliopsoas tendinitis) and extrinsic causes (spinal disease, trochanteric bursitis) that can be a source of pain.

There is no evidence based approach to manage these patients and no single test should be used to determine treatment. A thorough clinical evaluation is essential and blood tests are necessary to rule out infection. Imaging studies including plain radiographs and a MARs MRI are needed to evaluate either the stability of the prosthesis and to assess for the presence of pseudotumors and soft tissue destruction around the implant. Patients with symptomatic hips and evidence of muscle involvement on MRI require revision. Finally, the clinician must always be aware of the potential for systemic effects which require early and aggressive intervention to limit the adverse response to the metal and the metal bearing.