Incidence and treatment of abductor deficiency during total hip arthroplasty using the posterior approach: repair with direct suture technique and gluteus maximus flap transfer.

AIMS: The aims of this study were to assess the exposure and preservation of the abductor mechanism during primary total hip arthroplasty (THA) using the posterior approach, and to evaluate gluteus maximus transfer to restore abductor function of chronically avulsed gluteus medius and minimus. PATIENTS AND METHODS: A total of 519 patients (525 hips) underwent primary THA using the posterior approach, between 2009 and 2013. The patients were reviewed preoperatively and at two and five years postoperatively. Three patients had mild acute laceration of the gluteus medius caused by retraction. A total of 54 patients had mild chronic damage to the tendon (not caused by exposure), which was repaired with sutures through drill holes in the greater trochanter. A total of 41 patients had severe damage with major avulsion of the gluteus medius and minimus muscles, which was repaired with sutures through bone and a gluteus maximus flap transfer to the greater trochanter. RESULTS: Abductor strength was maintained in the normal hips, but lateral hip pain progressed significantly, five years postoperatively (p < 0.0001). In the 54 patients with mild abductor tendon damage treated with simple repair, lateral hip pain also increased significantly during follow-up (p = 0.002). In the 35 patients with severe avulsion but good muscle repaired using a gluteus maximus flap transfer, abductor function was restored. The six patients with complete avulsion and poor muscle did not regain strong abductor power, but lateral hip pain decreased. CONCLUSION: The posterior approach offered excellent exposure and preservation of the abductor mechanism during primary THA. Augmentation of the repair with a gluteus maximus flap provided stable reconstruction of the abductor muscles and seemed to restore function in the hips with functioning muscles. Cite this article: Bone Joint J 2019;101-B(6 Supple B):116-122.

Phase transformation, roughness, and microhardness of artificially aged yttria- and magnesia-stabilized zirconia femoral heads.

Yttria-stabilized zirconia ceramic (Y-TZP) has been used in total hip arthroplasty for many years but is susceptible to low-temperature aging. Medical-grade magnesia-stabilized zirconia (Mg-PSZ) is less commonly used; however, it has been shown to resist phase transformation. The purpose of this study was to directly compare the effects of artificial aging on phase transformation, surface roughness, and Vickers microhardness on Y-TZP and Mg-PSZ femoral heads. Y-TZP and Mg-PSZ heads were artificially aged in an autoclave in stages up to a total of 49 h. The surface roughness of Y-TZP significantly increased with each stage of artificial aging. Y-TZP heads aged for 49 h had a significantly higher monoclinic phase concentration and roughness, and a significantly lower microhardness, than nonaged Y-TZP heads. Artificial aging also caused the surface of Y-TZP to exhibit a lumpy "orange peel"-like appearance with a significantly higher mean peak height, suggesting that artificial aging causes individual grains to be pushed out of the surface. In contrast, artificial aging did not significantly affect the properties of Mg-PSZ heads. These findings suggest that Mg-PSZ is a satisfactory material for orthopaedic implant use, while Y-TZP, in the form tested, is not adequately stable for use as a bearing surface.

Prophylactic peri-operative local antibiotic irrigation.

An extensive review of the spinal and arthroplasty literature was undertaken to evaluate the effectiveness of local antibiotic irrigation during surgery. The efficacy of antibiotic irrigation for the prevention of acute post-operative infection after total joint arthroplasty was evaluated retrospectively in 2293 arthroplasties (1990 patients) between January 2004 and December 2013. The mean follow-up was 73 months (20 to 139). One surgeon performed all the procedures with minimal post-operative infection. The intra-operative protocol included an irrigation solution of normal saline with vancomycin 1000 mg/l and polymyxin 250,000 units/l at the rate of 2 l per hour. No patient required re-admission for primary infection or further antibiotic treatment. Two morbidly obese patients (two total hip arthroplasties) developed subcutaneous fat necrosis requiring debridement and one was revised because the deep capsular sutures were contaminated by the draining subcutaneous haematoma. One patient who had undergone total knee arthroplasty had unrecognised damage to the lateral superior geniculate artery and developed a haematoma that became infected secondarily four months after the surgery and underwent revision. The use of antibiotic irrigation during arthroplasty surgery has been highly effective for the prevention of infection in the author's practice. However, it should be understood that any routine prophylactic use of antibiotics may result in resistant organisms, and the wise stewardship of the use of antibiotics is an important part of surgical practice.

Intra-articular infusion: a direct approach to treatment of infected total knee arthroplasty.

Bactericidal levels of antibiotics are difficult to achieve in infected total joint arthroplasty when intravenous antibiotics or antibiotic-loaded cement spacers are used, but intra-articular (IA) delivery of antibiotics has been effective in several studies. This paper describes a protocol for IA delivery of antibiotics in infected knee arthroplasty, and summarises the results of a pharmacokinetic study and two clinical follow-up studies of especially difficult groups: methicillin-resistant Staphylococcus aureus and failed two-stage revision. In the pharmacokinetic study, the mean synovial vancomycin peak level was 9242 (3956 to 32 150; sd 7608 µg/mL) among the 11 patients studied. Serum trough level ranged from 4.2 to 25.2 µg/mL (mean, 12.3 µg/mL; average of 9.6% of the joint trough value), which exceeded minimal inhibitory concentration. The success rate exceeded 95% in the two clinical groups. IA delivery of antibiotics is shown to be safe and effective, and is now the first option for treatment of infected total joint arthroplasty in our institution.

Patellar tracking measurement in the normal knee.

Eleven fresh frozen cadaveric knee specimens were mounted in a knee kinematics test device, and normal patellar movements were evaluated with use of an external device for direct measurement of patellar movements. The effects of four different measurement conditions were assessed through alteration of one condition and determination of its effect on patellar kinematics with the use of six specimens. The four conditions included (a) change of the measuring axis from an axis parallel to the central axis of the femur (femoral axis) to one parallel to the central axis of the tibia (tibial axis), (b) rotation of the femoral axis internally 6 degrees, (c) change of the direction of the quadriceps force from parallel to the mechanical line of the lower extremity to a direction parallel to the femoral shaft, and (d) increase of the magnitude of the quadriceps force from 111 to 500 N. During knee flexion, the patella shifted laterally after a slight initial medial shift, tilted laterally from midflexion to 90 degrees, and gradually rotated medially. The patellar shift relative to the tibial axis appeared to be more medial than the shift measured relative to the femoral axis; the discrepancy was caused by the valgus position of the tibia relative to the femur. Changing the rotational angle of the femoral axis artificially changed the patellar position. Varying the direction of the quadriceps within the narrow range and increasing the quadriceps force did not affect patellar movements.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutrient pathways of the cruciate ligaments. An experimental study using the hydrogen wash-out technique.

We used the hydrogen wash-out technique to determine the rate of wash-out of an inert tracer from the posterior cruciate ligament in dogs and rabbits after we had detached the ligament from bone and synovial structures, and after we had isolated it from the synovial tissue with aluminum foil. These rates were compared with those from controls and no differences could be found between them. The uptake of tritiated proline administered intravenously was also shown not to be significantly different in the detached ligament as compared with an intact ligament. Isolation of the ligament from contact with the synovial lining prevented the uptake of hydrogen. Cruciate ligaments removed from the knee and placed in the suprapatellar pouch appeared viable after eight to ten days. These findings suggest that diffusion can serve as a major pathway for delivery of nutrients to the cruciate ligaments.

The effects of extraperiosteal and subperiosteal dissection. I. On blood flow in muscle.

Blood flow was studied in traumatized and untraumatized flexor digitorum longus muscles of rabbits before and after surgical dissection of the periosteum of the tibia. Neither extraperiosteal nor subperiosteal dissection diminished blood flow in untraumatized muscles, but when the muscles had been crushed, only extraperiosteal dissection appeared to severely compromise their collateral circulation. Because subperiosteal dissection did not diminish the blood flow in injured muscles, it seems to offer some advantages as a surgical approach to bone in a severely traumatized extremity.

The effects of extraperiosteal and subperiosteal dissection. II. On fracture healing.

The effects of subperiosteal and extraperiosteal dissection on the healing of tibial osteotomies were studied in fourteen rabbits killed three weeks after the osteotomy. Of the tibiae exposed subperiosteally, 71 per cent healed; of those exposed extraperiosteally, only 7 per cent had solid union. The first group had a significantly lower level of hydroxyproline in the callus and higher values for breaking load, breaking strength, and absorption of energy to failure. In ten animals that also had muscle transection at the osteotomy site, the rate and type of healing was similar whether no dissection, subperiosteal dissection, or extraperiosteal dissection had been done, but the callus showed lower calcium levels and higher hydroxyproline levels than in either of the groups with muscle trauma. This implies retardation of healing caused by muscle injury. Our data suggest that in the absence of muscle damage, subperiosteal dissection results in earlier healing than does extraperiosteal dissection. Muscle transection markedly retards healing; then, after transection, neither type of dissection appears to retard healing more than the other.

Subchondral route for nutrition to articular cartilage in the rabbit. Measurement of diffusion with hydrogen gas in vivo.

The route of nutrients going to articular cartilage was studied by determining the diffusion of hydrogen molecules from the subchondral circulation to the articular cartilage in rabbits. In all immature animals there was diffusion of hydrogen from subchondral bone into articular cartilage, while in the older immature animals the results were variable. None of the mature animals showed any diffusion of hydrogen into articular cartilage. The rate of diffusion of hydrogen was significantly lower in the articular cartilage than in the subchondral bone in the immature animals while the concentrations of hydrogen in the articular cartilage were only fractions of those in the subchondral bone at the same instant. Histologically, the deep layers of immature cartilage are penetrated extensively by vascular buds from the ossified portion of the epiphysis, while in adults the articular cartilage is separated from subchondral vascular spaces by an end-plate of bone. Blood vessels penetrating into the basilar layer of articular cartilage in immature animals appear to play an important role in the nutrition of articular cartilage coming from the subchondral region.

The effects of surgical procedures on the blood supply to the femoral head.

UNLABELLED: We have studied the effects of surgical procedures on the blood supply to the femoral head in adult dogs. The blood supply to normal adult canine femoral heads and osteoarthritic femoral heads was assessed by microvascular injection techniques and by measurement of the rate of blood flow by the hydrogen-washout technique. Circulation to the femoral head in the mature dog normally is dependent on retinacular vessels. Vascular anastomoses between the epiphysis and the metaphysis are generally not larger than capillary size. Reaming the femoral head does not devascularize the bone unless the retinacular vessels are disturbed. Stripping of the retinaculum, or combined reaming of the femoral head and stripping of the retinaculum, devascularized the femoral head in adult dogs with normal femoral heads. In the osteoarthritic hips, vascular anastomoses developed between the epiphysis and the metaphysis, so that stripping the retinaculum did not devascularize the femoral head. However, the rate of blood flow was decreased after combined reaming and retinacular stripping. CLINICAL RELEVANCE: In the non-arthritic hip or in one with early arthritis, the retinacular vessels are of primary importance to circulation to the femoral head. Damage to these vessels during surgery will lead to osteonecrosis in a high percentage of patients. The formation of vascular anastomoses between the epiphysis and the metaphysis during the development of osteoarthritis may make the arthritic femoral head less vulnerable. However, care should be taken to preserve retinacular vessels, since in this study the rate of blood flow was decreased by reaming the femoral head and stripping the retinaculum.

Femoral rotational alignment, based on the anteroposterior axis, in total knee arthroplasty in a valgus knee. A technical note.

The landmarks used to achieve correct rotational alignment of the femoral component in total knee arthroplasty may be indistinguishable or unreliable in the distal architecture of a valgus knee. Five observers identified the anteroposterior axis, the posterior condylar axis, and the transepicondylar axis in thirty cadaveric femora to determine the reliability of the use of each axis in the operative setting. In addition, radiographs were made of the distal aspect of each femur, the axes were constructed, and the angles were measured and compared with the visual measurements made by the observers. A line drawn perpendicular to the anteroposterior axis consistently approximated 4 degrees of external rotation relative to the posterior condylar surfaces. The transepicondylar axis was more difficult to define and was not as accurate. The radiographic results were similar to the visual results, but the standard deviations for the former were less than those for the latter. The anteroposterior axis appears to be a reliable landmark for rotational alignment of the femoral component in a valgus knee.

1980 Volvo award winner in basic science. Nutritional pathways of the intervertebral disc. An experimental study using hydrogen washout technique.

The pathways of material transfer to the intervertebral disc were studied in adult dogs by measuring diffusion of hydrogen molecules in the nucleus pulposus before and after disruption of the route through the annulus fibrosus and before and after disruption of the end-plate route. The interfaces was only in the central two-thirds of one side, caused significantly greater decrease in the rate of hydrogen washout than the disruption of the annulus route. Histologically, the bone-cartilage interface was frequently perforated by marrow cavity and vascular buds. These findings suggest that the end-plate route is a major pathway for material transfer to the intervertebral disc.

Nutrient pathways in transferred patellar tendon used for anterior cruciate ligament reconstruction.

With the use of the hydrogen washout technique, nutrient pathways of a Jones-type anterior cruciate substitution in the dog were examined. There was no hydrogen uptake by the graft of patellar tendon left attached to the tibia but isolated from the synovium. However, when the graft was placed against synovium in the intercondylar notch, hydrogen uptake and washout were not significantly different than when the patellar tendon was completely intact (control). We conclude that, at least initially, direct blood flow does not contribute to nutrition and that synovial diffusion may play a significant role in the sustenance of the graft.

Tibiofibular synostosis and recurrent ankle sprains in high performance athletes.

Recent evidence points toward a weight bearing and dynamic stabilizing function of the distal fibula in ankle joint mechanics. When fibular rotation and translation are restricted, ankle pain during weight bearing and push off often (but not always) results. The case histories of six professional athletes with distal tibial synostosis resulting from internal rotation-inversion injury confirm recent reports of ankle disability resulting from restriction of fibular motion, but suggest that there may be many patients with this lesion who are not disabled. Two patients with incomplete synostosis were asymptomatic, and one with complete synostosis had only occasional pain after vigorous exercise.

Clinical results of Whiteside Ortholoc total knee replacement.

Three hundred and four consecutive cementless Ortholoc I TKAs were followed for 2 to 5 years. One patient had femoral and tibial component loosening. There were no cases of patellar component loosening, but six knees had failure of the patellar polyethylene surface due to wear. A major design change of the metal-polyethylene locking mechanism was effected to address this problem. The patellar component is now countersunk and the central post has been reduced in size. 79.1 per cent of the knees were graded excellent, 13.4 per cent good, 5.8 per cent fair, and 1.7 per cent poor. The Ortholoc I group was compared to a similar group of 424 Ortholoc II knees at 1 year postoperatively for pain relief. The Ortholoc II knee differs from the Ortholoc I primarily in tibial component fixation, using four peripheral 6.5-mm screws. The Ortholoc II group had significantly fewer painful knees, which suggests that the screws in the tibial component were effective in improving fixation and controlling load distribution. Survival analysis showed no tendency for the results to deteriorate over the time span studied. Cementless fixation of all components, including the tibia and patella, was highly successful and can be achieved without stress relief of the distal femur.

Failure of cementless fixation of the femoral component in total hip arthroplasty.

The basic concepts involved in cementless fixation of the total hip arthroplasty femoral component have been controversial. Some clinicians advocate fixation only of the proximal portion of the stem so that weight-bearing loads will be transferred proximally, and proximal stress shielding will be avoided. Others advocate distal fixation to ensure rigidity of fixation but concede that it will lead to proximal stress shielding and bone loss. However, clinical evidence suggests that the design of the implant is one important factor in determining stress shielding. When the stem is smooth and cylindrical distally, proximal stress relief does not occur, even when the stem is fixed tightly distally. Because femoral component loosening is the most common clinical problem with cementless total hip arthroplasty, every effort should be made to achieve fixation of the implant. Proximal and distal fixation can be achieved with most of the available implants. For tight proximal fixation, a good proximal implant design and a precise line-to-line preparation technique are critical, but aggressive broaching and interference-fit techniques result in a high rate of proximal femoral fracture during preparation and implantation. When the conditions are good for excellent proximal fixation, a flexible stem should be selected to apply a large amount of stress proximally. The stress transferred through distal fixation will be small in this situation, and the reaming technique of the femoral diaphysis does not need to be very aggressive. Approximately 10 to 20 mm of tight distal fit combined with the 0.5-mm underreaming technique provides sufficient distal fixation, and the chance of distal femoral fracture during insertion of the stem is minimum with this technique. When conditions are unfavorable for excellent proximal fixation, such as in revision hip arthroplasty, or when a proximal deformity or osteoporosis is present, a relatively rigid stem should be selected to avoid overloading proximal fixation and, thus, generating large proximal micromotion. The stress transferred through distal fixation will be large in this situation, and a relatively aggressive but well-controlled reaming technique of the diaphysis is required. Approximately 20 to 40 mm of tight distal fit combined with a 0.5-mm underreaming technique is adequate to obtain sufficient distal fixation and still avoid distal femoral fracture. Implant design features that improve proximal fixation and instrumentation features that improve bone preparation and decrease the risk of failure will broaden the indications for cementless fixation. As fixation and instrumentation improve, more flexible implants can be developed to improve bone preservation and avoid proximal stress relief.(ABSTRACT TRUNCATED AT 400 WORDS)

Surgical exposure in revision total knee arthroplasty.

Extensile exposure is one of the crucial skills for managing the challenges presented by revision total knee arthroplasty. Full exposure is necessary to perform the intricate bone and ligament work, and short incisions combined with a timid approach to the quadriceps mechanism will result in inadequate reconstruction of the knee. Repair and reconstruction of the facial, subcutaneous, and cutaneous tissues to achieve closure are separate and equally important skills.

Cementless fixation issues in revision total knee arthroplasty.

Although massive solid allografts can be expected to vascularize and form new bone, variable amounts of replacement as well as collapse and necrosis may be prominent features of these large block allografts. Immunocompatibility seems to be an important factor in allograft healing and incorporation. Large block allograft of the acetabulum appears to be more likely to succeed if autograft is used. Rejection appears to be a significant factor in survival of large allografts. Although bone itself is not highly immunogenic, the role of marrow elements in the cancellous bone graft may be crucial. When possible, marrow contents should be washed carefully from the interstices of cancellous bone to remove cellular elements that do not contribute to osteoinduction but do produce an inflammatory immune response that can compromise healing and bone formation. Washing and soaking the components in antibiotic solution has the additional benefit of making available a reservoir of antibiotic that is released slowly during the postoperative period. Morcellized cancellous bone, rather than finely ground bone which tends to be destroyed by phagocytosis, is the best available choice for reconstructing large volumes of deficient bone stock. Fixation is completely dependent on the existing bone, so that massive defects must be protected until sufficient rigidity develops in the grafted material to allow sharing of weightbearing loads. Clinical experience has shown that migration of the tibial component after reconstruction with morcellized allograft is rare during the first 2 to 5 years after surgery (Fig. 8). These results are surprising in light of reported experience with structural allografts of the acetabulum. Jasty and Harris reported loosening of acetabular components after 4 years in 32% of their cases. The biologic behavior of morcellized allograft differs from that of block allograft, however. Vascularization and ossification are rapid and a permanent, competent loadbearing structure is achieved by filling large deficient areas. The biologic response obtained with the correct technique appears to be early and vigorous. It does not seem likely that progressive collapse would occur after remodeling and healing have been established (Fig. 9). Bone graft handling probably is crucial to the success of grafting of the knee. Antibiotic soaking and washing, removal of bone marrow, and adequate support of the implants are all necessary factors for consistent success of this technique. The results of this salvage procedure have been encouraging. The grafting technique appears to provide long-term support for the implants, so that repeat revision is unlikely.

Rotational stability of noncemented total hip femoral components.

Achieving torsional fixation of the femoral component in total hip arthroplasty is an important factor in success of the implant, so design features that improve fixation are likely to improve clinical results. Four femoral stem designs that allow different levels of femoral neck resection and use different distal fixation techniques were mechanically tested in cadaveric femurs to determine resistance to torsional loads. Five specimens for each stem design were implanted according to the standard procedure, and each was axially and torsionally loaded in a servohydraulic testing machine. Rotational interface micromotion and interface slippage were measured at the bone-implant interface. Decreased micromotion and interface slippage were associated with a distal scratch fit and neck retaining design, and the combination of distal scratch fit and neck retention had the least micromotion and smallest standard deviation of the four designs.

Effect of neck resection on torsional stability of cementless total hip replacement.

Loosening of the femoral component in total hip arthroplasty commonly results from inadequate resistance to torsional loads. We evaluated 20 adult human cadaver femora to determine the effect of different neck-resection levels on torsional resistance of the femoral component. All specimens were prepared for fixation with the Impact modular total hip replacement. Each femoral diaphysis was overreamed 2 mm to achieve only proximal fixation. The specimens were then divided into groups of five and implants were inserted with the precision press-fit technique. Each specimen was loaded in an Instron stress-testing device. A linearly variable differential transducer was then attached to the specimen to measure micromotion at the medial interface between the implant and bone. Each specimen was loaded until failure occurred. When all of the neck was preserved, torsional load to failure was significantly better than in the 50%, 15%, and 0% neck-preservation specimens. At a 20 N-m torsional load, the 100% and 50% neck preservation specimens had similar micromotion, but the 15% and 0% specimens had gross motion and a large standard deviation at this load level. Without distal fixation, the femoral component is highly dependent on proximal geometry for resistance to torsional loading. Preserving the femoral neck provides an effective means of resistance. Maintaining the entire femoral neck most effectively reduces miromotion at low loads, but maintaining the midshaft area of the femoral neck appears to most effectively control micromotion at higher torsional loads. Resection below the midshaft of the neck markedly decreases the torsional load-bearing capacity of the proximal femur.