Previous work has demonstrated increased implant failure in patients with DDH compared to osteoarthritis with historic methods and implants. This study examines outcomes of modern total hip arthroplasty (THA) techniques using uncemented fixation and cross-linked PE (XLPE) bearings for DDH.

A consecutive series of 879 patients with DDH who underwent primary THA with uncemented components and a XLPE bearing at a single institution between 1999 and 2016 were identified. Mean age at index arthroplasty was 51 years, with 78% females. Mean follow-up was 8 years.

5- and 10-year survivorships free of revision were 98.4% and 98%, respectively. 5- and 10-year survivorships free of reoperation for any reason were 97% and 96%, respectively. Survivorship free of acetabular revision for aseptic loosening was 99.8% at 5 and 10 years, while survivorships free of femoral revision for aseptic loosening were 99.7% at 5 years and 99.5% at 10 years. Survivorship free of reoperation for PE damage (2 liner fractures, 2 rim damage from impingement) was 99.3% at 10 years. There were no revisions for bearing surface wear or osteolysis. 13% of patients experienced complications (4% dislocation, 3.3% wound complication rate). Ten-year survivorship free of reoperation for instability was 99.2%. 8 patients developed infection requiring operation (<1%). 100 patients had a prior pelvic osteotomy (11%), which did not increase rate of complications (p=0.22) or reoperations (p=0.51).

Fixation with modern uncemented implants has dramatically reduced implant loosening in patients with DDH, and the use of XLPE bearings has markedly reduced revision for PE wear/osteolysis in this young patient population, leading to dramatically improved mid/long-term survivorship compared to historic series.

Patients who are actively smoking at the time of primary total joint arthroplasty (TJA) are at considerably increased risk of perioperative complications. Therefore, strategies to assist patients with smoking cessation before surgery have become routine practice. A secondary benefit is the theoretical catalyst for long-term smoking cessation. However, questions remain as to whether patients actually cease smoking prior to the procedure, and if so, how long this lasts postoperatively.

Our high-volume, academic institution documents self-reported smoking status at each clinic visit (at 6-month intervals), as well as at the time of surgery through a total joint registry. As such, all patients who underwent TJA from 2007 to 2018 were identified and grouped as: non-smokers, smokers (regularly smoking cigarettes within 1 year from surgery), and former smokers (those who quit smoking within a year before surgery). Thereafter, smoking status in the postoperative period was assessed, with special attention to the former smokers in order to see who remained smoke-free.

From the 28,758 primary TJAs identified, 91.3% (26,244) were non-smokers, 7.3% (2,109) were smokers, and 1.4% (405) had quit smoking before surgery. Among patients who quit smoking before surgery, only 38% were still abstinent at 9 years from surgery. Conversely, 24% of smokers at the time of surgery eventually quit and 3.1% of non-smokers started smoking over the same time period.

Despite a concerted effort to help patients stop smoking before TJA, an important proportion (7.3%) are unsuccessful. Among those patients who do manage to stop smoking, only a minority (38%) remain smoke-free after surgery. Compared to current smokers, patients who managed to quit before surgery are more likely to remain smoke-free after surgery. These findings highlight that smoking remains a tremendous challenge in contemporary TJA practices. Additional strategies targeting smoking cessation before after surgery are needed.

There are numerous factors that influence total hip arthroplasty (THA) stability including surgical approach, soft-tissue tensioning, impingement, abductor status, and component positioning. A long-held tenet regarding acetabular component positioning is that cup inclination and anteversion of 40 ± 10 degrees and 15 ± 10 degrees, respectively, represents a “safe zone” as to minimise dislocation after primary THA. However, several studies have recently challenged that notion for individual patients. A study completed by Abdel et al. identified a cohort of 9784 primary THAs performed at a single institution with 206 THAs (2%) that subsequently dislocated. The authors determined that 58% of the dislocated THAs had their acetabular component within the safe zone for both acetabular inclination and anteversion. When looked at separately, 84% had their inclination within the safe zone (mean value of 44 ± 8 degrees), and 69% had their anteversion within the safe zone (mean value of 15 ± 9 degrees). As such, surgeons should take into account that cup positioning alone does not determine the risk of instability following THA, as there are a multitude of other factors that can contribute to dislocation. Hip stability is multifactorial and likely patient-specific, and must take into account bony and muscular anatomy, static and dynamic soft tissue balance and intraoperative tensioning, and the functional demand and rehabilitative efforts of the patient.

Simultaneous bilateral total hip arthroplasties (THAs) present unique and unwarranted dangers to the patient and surgeon alike. These include a significantly increased risk of blood transfusion (up to 50% in contemporary series even with the use of tranexamic acid), longer operative times, longer length of stays, and higher mortality rates in patients with minimal risk factors (age > 75 years, rheumatoid arthritis, higher ASA class, and/or male sex). This is even in light of the fact that the vast majority of literature has a substantial selection bias in which only the healthiest, youngest, non-obese, and most motivated patients are included.

Traditionally, simultaneous bilateral THAs were completed in the lateral decubitus position. This required the surgeon and surgical team to reposition the patient onto a fresh wound, as well as additional prepping and draping. To mitigate these additional limitations of simultaneous bilateral THAs, there has been a recent trend towards utilizing the direct anterior approach. However, this particular approach presents its own unique set of complications such as an increased risk of periprosthetic femoral fracture and early femoral failure, an increased risk of impaired wound healing (particularly in obese patients), potential injury to the lateral femoral cutaneous nerve with subsequent neurogenic pain, and traction-related neurologic injuries. When compounded with the risks of simultaneous bilateral THAs, the complication profile becomes prohibitive for an elective procedure with an otherwise very low morbidity.

Pelvic discontinuity is defined as a separation of the ilium superiorly from the ischiopubic segment inferiorly. In 2018, the main management options include the following: 1) hemispheric acetabular component with posterior column plating, 2) cup-cage construct, 3) pelvic distraction, and 4) custom triflange construct. A hemispheric acetabular component with posterior column plating is a good option for acute pelvic discontinuities. However, healing potential is dependent on host's biology and characteristic of the discontinuity. The plate should include 3 screws above and 3 screws below the discontinuity with compression in between. In addition, the hemispherical acetabular component should have at least 50% host bone contact with 3–4 screws superior and 2–3 screws inferior to the discontinuity. On the other hand, a cup-cage construct can be used in any pelvic discontinuity. This includes a highly porous acetabular component placed on remaining host bone. Occasionally, highly porous metal augments are used to fill the remaining bone defects. A supplemental cage is placed over the acetabular component, spanning the discontinuity from the ilium to the ischium. A polyethylene liner is then cemented into place with antibiotic-loaded bone cement. Rarely, pelvic distraction may be needed. With this technique, pelvic stability is obtained via distraction of the discontinuity by elastic recoil of the pelvis and by fixing the superior hemipelvis and inferior hemipelvis to a highly porous metal cup or augment with screws, thereby unitizing the superior and inferior aspects of the pelvis. In essence, the cup acts as a segmental replacement of the acetabulum, with healing occurring to the cup or augment, resulting in a unitised hemipelvis. Frequently, the discontinuity itself does not achieve bony healing. Finally, custom triflange constructs are being utilised with increasing frequency. Triflange cups are custom-designed, porous and/or hydroxyapatite coated, titanium acetabular components with iliac, ischial, and pubic flanges. Rigid fixation promotes healing of the discontinuity and biologic fixation of the implant. It requires a CT scan, dedicated preoperative design, and fabrication costs.

Pulsed Electromagnetic Fields (PEMFs) promote joint tissue anabolic activities, particularly in cartilage and bone. Here we investigated the effect of selected PEMFs (75Hz, 1.5mT, 1.3msec) in a differentiating model of murine myoblasts (C2C12) in vitro. C2C12 were seeded at 5×10³ cells/cm² in 4 well plates and left to adhere for 24h. Subsequently, cells were either maintained in growth medium (GM) or induced towards myogenic differentiation in low-serum conditions, with and without PEMF exposure, for 4 days. Morphological analysis, myotube formation and fusion index (FI) were assessed with fluorescence microscopy techniques. Metabolic activity was determined by MTT; moreover, a multiplex cytokine array (RayBiotech) allowed cell supernatant molecule quantification. Cells exposed to PEMFs in GM acquired a distinctive elongated morphology, with increased bi-nuclear figures (3.2-fold FI increase over PEMF-unexposed cells) and displayed a significantly higher metabolic activity (+31%, p<0.05 over PEMF-unexposed cells). PEMF exposure increased metabolic activity also under myogenic differentiation (+15% over PEMF-unexposed differentiating cells, p<0.05), with the formation of long, thick polynuclear myotubes, suggesting a role of PEMFs in enhancing myogenesis (7.7-fold FI increase over PEMF-unexposed cells). 4-day culture supernatants revealed the presence of several myokines (KC/CXCL1, LIX, MCP-1, TIMP-1). Preliminary analysis showed a 1.16-fold increase (n=2) of LIX and, notably, a 1.91-fold increase (n=2) of TNF-RI, in cell supernatants of PEMF-exposed over PEMF-unexposed cells. Collectively, these results suggest that PEMF may successfully be applied in models of muscle cell trauma to optimise muscle fibre repair, by fine-tuning the release of myokines, promoting myoblast proliferation and myotube formation.

Highly porous tantalum cups have been used in complex acetabular revisions for nearly 20 years but reports of long term results are limited. This study was designed to report ten year results of revision using a single porous tantalum cup design with special attention to re-operation for any reason, all-cause revision, and revision for aseptic loosening.

Retrospective review of all revision THA cases performed from 1999–2006 using a highly porous tantalum acetabular component design with multiple screw holes and a cemented polyethylene liner (Zimmer Biomet, Warsaw, IN). Our institutional medical record and total joint registry were used to assess follow-up and xrays were reviewed. The Paprosky classification system was used to rate acetabular bone loss. Radiographic loosening was defined as new/progressive radiolucencies in all 3 acetabular zones, or cup migration (>2mm). Kaplan-Meier survivorship was used to assess survivorship free of cup revision/removal for any reason, and free of revision for aseptic loosening.

Between 1999 and 2006 this tantalum cup was used in 916 revisions. Mean age: 66 (±6), BMI: 29 (±6), and male: 42%. Indications for revision: aseptic loosening 346 (38%), osteolysis 240 (26%), and infected arthroplasty 168 (18%). Large (3A or 3B) bone defects were present in 260, and pelvic discontinuity in 61. Reoperation for any reason: 133 (15%), but 84 of 133 cases did not require cup revision for instability (38) or femoral failure (24). Tantalum cup removal/revision was required in 49 (5.3%) for deep infection (39) and recurrent dislocation (6), and aseptic loosening (4). 10 year survivorship free of cup revision for any reason: 95% and for aseptic loosening: 99%. Radiographic review (mean 10 years): suspicious for aseptic loosening in another 4 cups.

A highly porous tantalum acetabular component with multiple screws and a cemented polyethylene insert provided durable long term fixation for an array of acetabular revision problems. Long term aseptic loosening was very rare (<1%) and cup removal was mainly related to deep infection, and rarely dislocation.

Assess union rate, complications, and outcomes of large series of contemporary extended trochanteric osteotomies (ETOs) performed during revision THAs.

From 2003 to 2013, 612 ETOs were performed during revision THAs using 2 techniques. 367 were Paprosky type and 245 were Wagner type. Indications were aseptic loosening (65%), periprosthetic joint infection (18%), periprosthetic fracture (6%), femoral implant fracture (5%), and other (6%). Mean age 69 years, 58% male. Median follow-up 5 years (range, 2.1 to 13 years).

Mean Harris Hip Scores increased from 57 preoperatively to 77 at latest follow-up (p=0.0001). Radiographic union of the extended osteotomy occurred in 98%. There were 9 ETO nonunions. Mean time to union of the distal transverse osteotomy was 5.9 months (range, 1 month − 2 years). Mean trochanteric osteotomy fragment migration prior to union was 3 mm (range, 0–29 mm). Over 1 cm of migration occurred in 7.4%. Intraoperative fracture of the ETO diaphyseal fragment occurred in 4%, and postoperative greater trochanter fractures in 8.8%. Other complications: dislocation in 5.7% and infection in 3.4%. Dislocation occurred in 19 of 462 with ETO migration < 1 cm and 4 of 39 with ETO migration ≥1 cm (p=0.08). Ten year survivorship free of revision for aseptic femoral loosening, free of any component removal or revision, and free of reoperation were 97%, 91%, and 82%, respectively.

The union rate after ETO was high and notable trochanteric migration was infrequent. The most common complication was fracture intraoperatively or postoperatively of the osteotomy fragment.

Over the past 30 years, cemented, cementless, and hybrid fixation options have been utilised with various total knee arthroplasty (TKA) implant systems. While cemented components are widely used and considered the most reliable method of fixation, historical results may not be applicable to contemporary patients, who are increasingly younger than 65 years of age. Moreover, the literature is not definitive on which method of TKA fixation obtains the best clinical, functional, and radiographic results. A recent Cochrane meta-analysis on roentgen stereophotogrammetric analysis (RSA) included five randomised clinical trials (RCTs) in 297 participants. The authors observed that cemented fixation of tibial components demonstrated smaller displacement in relation to cementless fixation. However, the risk of future aseptic loosening with uncemented fixation was approximately half that of cemented fixation (risk ratio = 0.47, 95% CI 0.24 to 0.92) with a 16% absolute risk difference between groups. Almost all included studies recorded functional measures of Knee Society and Hospital for Special Surgery knee scores, but the authors of each study found no significant difference between the groups. Recently, highly porous metals have become an attractive fixation option in TKA due to their biomechanical properties. In a large RCT of 397 patients, Pulido et al found that uncemented highly porous metal tibias provided comparably durable fixation and reliable pain relief and restoration of function when compared with traditional cemented modular tibias. While longer term studies are needed, cementless TKAs may be a durable and reliable alternative with highly porous metals, particularly in younger patients.

There are numerous factors that influence total hip arthroplasty (THA) stability including surgical approach, soft-tissue tensioning, impingement, abductor status, and component positioning. A long-held tenet regarding acetabular component positioning is that cup inclination and anteversion of 40 degrees ± 10 degrees and 15 degrees ± 10 degrees, respectively, represents a “safe zone” as to minimise dislocation after primary THA. However, several studies have recently challenged that notion for individual patients. A study completed by Abdel et al identified a cohort of 9784 primary THAs performed at a single institution with 206 THAs (2%) that subsequently dislocated. The authors determined that 58% of the dislocated THAs had their acetabular component within the safe zone for both acetabular inclination and anteversion. When looked at separately, 84% had their inclination within the safe zone (mean value of 44 degrees ± 8 degrees), and 69% had their anteversion within the safe zone (mean value of 15 degrees ± 9 degrees). As such, surgeons should take into account that cup positioning alone does not determine the risk of instability following THA, as there are a multitude of other factors that can contribute to dislocation. Hip stability is multifactorial and likely patient-specific, and must take into account bony and muscular anatomy, static and dynamic soft tissue balance and intra-operative tensioning, and the functional demand and rehabilitative efforts of the patient.

Acetabular fractures can occur due to either low or high-energy trauma, and treatment can consist of non-operative management, open reduction and internal fixation (ORIF), or total hip arthroplasty in either the acute or chronic setting. These decisions are often based on the age of the patient, the fracture pattern, and the existence of pre-fracture hip debility. In the acute setting, younger patients should undergo ORIF with anatomic reduction of the fracture, while total hip arthroplasty (THA) may be considered for elderly patients with pre-existing hip arthritis. Several factors can expedite the onset of post-traumatic arthritis in the former, including difficult fracture patterns, fractures that are intra-articular in nature, or fractures involving the femoral head. A meta-analysis of seven studies with 685 patients from all age groups reported the incidence of post-traumatic arthritis following satisfactory reduction of acetabular fractures (≤2 mm) to be 13.2%. Unsatisfactory reductions (>2 mm) increased the incidence of post-traumatic arthritis to 43.5%. Factors affecting the reduction quality include fracture type, fracture characteristics (e.g. comminution, impaction), time to surgery, and experience level of the operative team. In such settings, salvage THAs can be considered. However, complications including aseptic loosening, instability, and periprosthetic infection are more common than for other indications leading to THA. In our experience, at 20 years, we found that THAs performed after operatively treated acetabular fractures still had excellent hip function, and a 70% survivorship free of aseptic acetabular revision. A more recent study of 30 primary THAs performed with highly porous acetabular components indicated excellent results as well. As such, if early complications can be avoided, patients can expect substantial pain relief and excellent durability.

Uncemented component retention with polyethylene (PE) liner and femoral head exchange is commonly used to treat periprosthetic osteolysis. The purpose was to determine long-term implant survivorship, risk factors for aseptic failures, clinical outcomes, and complications following PE liner and head exchange.

We identified 116 hips in 110 patients treated with PE liner and head exchange for osteolysis from 1993 to 2004. The mean age was 58, 64 were women, and mean follow-up was 11 years.

Implant survivorship free from all-cause revisions was 91% at 5-years, 81% at 10-years, and 69% at 15-years. Reasons for re-revision included subsequent conventional PE wear and osteolysis in 7 (6%), aseptic acetabular loosening in 5 (4%), and instability in 5 hips (4%). Mean time to revision for aseptic acetabular loosening was 4 years (range 1 – 7 years). Risk factors for aseptic acetabular loosening included acetabular zones of pre-revision osteolysis, percentage of cup involvement, and size of osteolytic defects. Absolute risk of acetabular loosening was 23% for three zones of osteolysis (Relative Risk (RR) 12, p<0.01), 40% if osteolysis involved more than half the cup circumference (RR 14, p<0.01), and 21% for defects greater than 600 mm² (RR 11, p<0.01). Harris hip scores improved from 77 to 87 (p<0.01). The most common complication was dislocation (16%).

These data quantify risk of subsequent component loosening when well fixed, uncemented implants are retained during operations for osteolysis, and may inform operative decisions regarding shell retention versus revision.

Blood conservation is an essential aspect of total hip arthroplasty (THA). As recently as 10 years ago, it was standard practice across North America for patients to undergo pre-operative autologous blood donation (PAD) prior to an elective TJA. Though the cost of PAD is about the same as allogenic blood transfusion, it has fallen out of favor due to mixed results.

Instead, most surgeons have implemented a practice of obtaining pre-operative hemoglobin levels. If anemia is diagnosed, the patient should be worked up for the underlying cause. In cases of pre-operative anemia where a specific deficiency cannot be elucidated, consideration can be given to the use of erythropoietin (EPO).

The routine use of tranexamic acid (TXA) has become the standard of care at most institutions since it is safe, inexpensive, easy to administer, and very effective at minimizing peri-operative blood transfusion. Intravenous TXA can be administered effectively in a variety of different ways and a number of different protocols are described. The popularised Mayo Clinic protocol is to administer TXA once prior to incision (1g IV in 50mL of normal saline) and once during wound closure.

Acute normovolemic hemodilution is a technique utilised just before or after the induction of anesthesia in which whole blood is removed while keeping the patient normovolemic with acellular fluids (i.e. crystalloids or colloids). This technique is rarely used.

Hypotensive anesthesia is a technique utilised to keep mean arterial pressures (MAP) at a level around 50mm Hg. It appears to be most effective with the use of epidural anesthesia. Certain patients may not be good candidates for hypotensive anesthesia (high cardiac risk factors), but it can be an effective corollary to other intra-operative measures.

Historically, many surgeons practiced reflexive transfusion protocols rather than treating patients on an individual basis. Current practice has adopted a more pragmatic approach to transfusion. Specifically, patients are assessed for signs of anemia and are often allowed to drift well below 8g/dL as long as they remain asymptomatic and have a suitable cardiac risk.

Over the past several decades, cementless femoral fixation for primary total hip arthroplasties (THAs) has become more common in North America. It is estimated that nearly 90% of all primary THAs completed in the United States are cementless. In the Australian National Joint Replacement Registry, the use of cementless fixation has increased from 51.3% in 2003 to 63.3% in 2015. During the same time period, cemented fixation declined from 13.9% to 3.7%, but hybrid fixation was relatively stable at about 33%. This is likely related to the fact that multiple institutional and national registries have shown a higher rate of intra-operative periprosthetic femoral fractures with the use of cementless femoral components in certain patient populations. Those risk factors include patients greater than 65 years of age, female patients, and those with significant osteoporosis and Dorr C canals.

However, it is important to note that not all cementless femoral components are similar. In fact, there is great variation in not only the geometry of cementless femoral components, but also in the type and extent of the biologic ingrowth surfaces. Each design has unique advantages and disadvantages. While some cementless femoral components are indicated for the general population, some are more specific and tailored to complex primary THAs (such as developmental dysplasia of the hip or post-traumatic arthritis with intra-operative concern for femoral version and thus hip stability) or revision procedures where distal fixation is needed (such as those with periprosthetic fractures or lack of proximal metaphyseal bony support).

In 2000, Berry first described the evolution of cementless femoral components based upon distinct geometries that govern where fixation is obtained. This was modified in 2011 by Khanuja et al. to include six general types of cementless femoral components based upon shape. These include the following: Type 1: Single wedge; Type 2: Double edge with metaphyseal filling; Type 3: Tapered - A: Tapered round, B: Tapered spline/cone, C: Tapered rectangle; Type 4: Cylindrical fully coated; Type 5: Modular; Type 6: Anatomic.

Type 1, 2, and 6 cementless femoral components obtain fixation in the metaphysis, whereas Type 3 stems obtain fixation in the metaphyseal-diaphyseal junction. Type 4 stems obtain fixation in the diaphysis. Type 5 stems can obtain fixation in either the metaphysis or the diaphysis.

Within each type of stem, specific implant designs have had excellent long-term survivorship, while other specific implant designs have had higher than expected failure rates. Type 1 stems have the most published reports, and most contemporary reports indicate a stem survivorship greater than 95% at 15–20 years. Similar findings have been documented with specific implants from other types of stems when appropriate indications and surgical technique are utilised. Of note, one class of stems that has shown early failures due to adverse local tissue reactions (ALTR) is that of dual-modular necks. On the other hand, modular fluted tapered stems continue to produce excellent long-term data in complex primary THAs, as well as difficult revision THAs.

Over the past 30 years, cemented, cementless, and hybrid fixation options have been utilised with various total knee arthroplasty (TKA) implant systems. While cemented components are widely used and considered the most reliable method of fixation, historical results may not be applicable to contemporary patients, who are increasingly younger than 65 years of age. Moreover, the literature is not definitive on which method of TKA fixation obtains the best clinical, functional, and radiographic results. A recent Cochrane meta-analysis on roentgen stereophotogrammetric analysis (RSA) included five randomised clinical trials (RCTs) in 297 participants. The authors observed that cemented fixation of tibial components demonstrated smaller displacement in relation to cementless fixation. However, the risk of future aseptic loosening with uncemented fixation was approximately half that of cemented fixation (risk ratio = 0.47, 95% CI 0.24 to 0.92) with a 16% absolute risk difference between groups. Almost all included studies recorded functional measures of Knee Society and Hospital for Special Surgery knee scores, but the authors of each study found no significant difference between the groups. Recently, highly porous metals have become an attractive fixation option in TKA due to their biomechanical properties. In a large RCT of 397 patients, Pulido et al found that uncemented highly porous metal tibias provided comparably durable fixation and reliable pain relief and restoration of function when compared with traditional cemented modular tibias. While longer-term studies are needed, cementless TKAs may be a durable and reliable alternative with highly porous metals, particularly in younger patients.

Ten to 15% of the pelvic girdle tumors are primary malignant bone tumors, while about 80% are osseous metastases. Due to improved function, enhanced quality of life, and acceptable local recurrence rates, limb salvage surgery has replaced external hemipelvectomies in many cases of primary malignancies. However, large segmental bony defects and poor bone quality due to the disease process itself and subsequent treatment (i.e. chemotherapy and radiation) can make stable implant fixation difficult when performing a total hip arthroplasty (THA) for oncologic periacetabular lesions with concurrent fractures. Various methods are available to reconstruct the hemipelvis, and include large structural allografts, allograft-prosthetic composites (APCs), custom-made endoprostheses, modular saddle prostheses, and modular hemipelvis endoprostheses. However, short- and mid-term results from our institution indicate that tantalum reconstructions with adjuvant screw fixation and supplemental reinforcement cages provide reasonable improvement in clinical outcomes and stable fixation in situations with massive bone loss and compromised bone quality. On the femoral side, cemented fixation remains a viable option (including proximal femoral replacements), but uncemented distal fixation with extensively-porous coated cylindrical stems or modular fluted tapered stems can be considered if the disease process (or subsequent treatment) primarily affects the proximal femur. In addition to long-term fixation, post-operative dislocations remain a significant concern given the often compromised abductor mechanism.

Larger diameter femoral heads and improved operative approaches and soft tissue repair/closure have somewhat reduced the incidence of recurrent instability after total hip arthroplasty (THA). Nevertheless, hip instability remains one of the most common reasons for reoperation after THA, and accounts for roughly a quarter of hip revisions in the United States in Medicare patients. The prevalence of instability after THA varies widely, from 0.3% to 15%. Surgeons have come to understand that hip instability can be caused by implant malposition, impingement, and inadequate soft tissue tension or integrity. While the cumulative risk of instability is acceptable at approximately 2.8% with transtrochanteric approaches, this is based upon the trochanter actually healing (and often being advanced). On the other hand, trochanteric nonunion and proximal migration have been noted by many, and this frequently results in catastrophic instability. Moreover, and importantly, abductor insufficiency is one the most difficult causes of hip instability to solve. Woo and Morrey reported a 17.6% instability rate when trochanteric nonunion occurred with 1 cm proximal trochanteric migration. Alternatively, the contemporary incidence of instability with the posterolateral or anterolateral approaches, and an adequate soft tissue repair, is approximately 1–2%.

Complications involving the knee extensor mechanism occur in 1% to 12% of patients following total knee arthroplasty (TKA), and have negative effects on patient outcomes. While multiple reconstruction options have been described, the results in patients with a prior TKA are inferior to those in patients without a TKA. However, optimistic results have been reported by Browne and Hanssen with the use of a synthetic mesh (knitted monofilament polypropylene)3. In this technique, a synthetic graft is created by folding a 10 × 14 inch sheet of mesh and securing it with nonabsorbable sutures. A burr is then used to create a trough in the anterior aspect of the tibia to accept the mesh graft. The graft is inserted into the trough and secured with cement. After the cement cures, a transfixion screw with a washer is placed. A portal is subsequently created in the lateral soft tissues to allow delivery of the graft from deep to superficial. The patella and quadriceps tendon are mobilised, and the graft is secured with sutures to the lateral retinaculum, vastus lateralis, and quadriceps tendon. The vastus medialis is then mobilised in a pants-over-vest manner over the mesh graft, and secured with sutures. Finally, the distal arthrotomy is closed tightly to completely cover the mesh graft with host tissue. In their series, Browne and Hanssen noted that 9 of 13 patients achieved an extensor lag of > 10 degrees with preserved knee flexion and significant improvements in the mean Knee Society scores for pain and function.

Complications involving the knee extensor mechanism occur in 1% to 12% of patients following total knee arthroplasty (TKA), and have negative effects on patient outcomes. While multiple reconstruction options have been described, the results in patients with a prior TKA are inferior to those in patients without a TKA. However, optimistic results have been reported by Browne and Hanssen with the use of a synthetic mesh (knitted monofilament polypropylene). In this technique, a synthetic graft is created by folding a 10 × 14 inch sheet of mesh and securing it with nonabsorbable sutures. A burr is then used to create a trough in the anterior aspect of the tibia to accept the mesh graft. The graft is inserted into the trough and secured with cement. After the cement cures, a transfixion screw with a washer is placed. A portal is subsequently created in the lateral soft tissues to allow delivery of the graft from deep to superficial. The patella and quadriceps tendon are mobilised, and the graft is secured with sutures to the lateral retinaculum, vastus lateralis, and quadriceps tendon. The vastus medialis is then mobilised in a pants-over-vest manner over the mesh graft, and secured with sutures. Finally, the distal arthrotomy is closed tightly to completely cover the mesh graft with host tissue. In their series, Browne and Hanssen noted that 9 of 13 patients achieved an extensor lag of <10 degrees with preserved knee flexion and significant improvements in the mean Knee Society scores for pain and function.

Summary

Based upon genetic analysis, decorin is an exciting pharmacologic agent of potential anti-fibrogenic effect on arthrofibrosis in our animal model.