3. Adult Reconstruction (Hip & Knee) MCQs

This patient has demonstrated recurrent instability, and her current implants lack the modularity to upsize and improve the head-neck ratio and range to impingement. Given the monoblock acetabular component and a +7-mm neck length, the best option is revision to a large-diameter femoral head or dual-mobility component.

In type B3 fractures, the proximal femur is so deficient that it cannot be treated with open reduction and internal fixation or support a new femoral component. In younger patients, the femur can be reconstructed with allograft prosthesis composite to restore bone stock. Removal of the distal stem with trephines would compromise fixation with cement. Elderly and low-demand patients can be treated more simply with a cemented segmental replacement prosthesis, such as that used for tumor reconstruction.

Figures 1 through 5 are the radiographs and CT scans of a 67-year-old man who has had intermittent anterior and medial pain since his left total knee arthroplasty (TKA) 12 years ago. Examination reveals full range of motion and positive posterior drawer. His pain has been recalcitrant to physical therapy, nonsteroidal anti-inflammatory drugs, and brace treatment. What is the most appropriate treatment?

All of the options, except cementing the metaphyseal portion and press fitting the keel of the tibial component, have been shown to create strong and long-lasting constructs; however, cementing of both the platform and the keel offers the most predictable solution. Cementing the platform and not the keel has been shown to have a higher loosening rate than the more traditional methods of fully cementing or using screws to augment fixation.

A study by Boyd et al. was performed to determine patellar complications after TKA, with the use of an unconstrained prosthesis, with and without resurfacing of the patella. Chronic pain (post-operative, peripatellar pain) in the group that had not had resurfacing was noted in 40 (13 percent) of the 300 knees that were affected by inflammatory arthritis (rheumatoid arthritis [RA], juvenile RA and miscellaneous subcategories), and in 11 (6 percent) of the 195 knees affected by degenerative osteoarthrosis. A revision to resurface the patella was performed in all 51 knees that caused chronic pain and had not had resurfacing of the patella. Hence, chronic pain after TKA without resurfacing the patella was more common in knees affected by rheumatoid arthritis than in those affected by degenerative osteoarthritis. The authors of the study recommend that the patella be resurfaced when an unconstrained prosthesis is used in patients with a diagnosis of inflammatory arthritis and to a lesser degree osteoarthrosis.

Both the American Academy of Orthopaedic Surgeons (AAOS) and AdvaMed, the medical device manufacturer's trade organization, have written guidelines that address potential conflicts of interest regarding interactions between physicians and manufacturer's representatives when it comes to patients' best interest. The AAOS feels that the orthopaedic profession exists for the primary purpose of caring for the patient and that the physician-patient relationship is the central focus of all ethical concerns. When an orthopaedic surgeon receives anything of significant value from industry, a potential conflict of interest exists. The AAOS believes that it is acceptable for industry to provide financial and other support to orthopaedic surgeons if such support has significant educational value and has the purpose of improving patient care. All dealings between orthopaedic surgeons and industry should benefit the patient and be able to withstand public scrutiny. A gift of any kind from industry should in no way influence the orthopaedic surgeon in determining the most appropriate treatment for his or her patient. Orthopaedic surgeons should not accept gifts or other financial support with conditions attached. Subsidies by industry to underwrite the costs of educational events where CME credits are provided can contribute to the improvement of patient care and are acceptable. A corporate subsidy received by the conference's sponsor is acceptable; however, direct industry reimbursement for an orthopaedic surgeon to attend a CME educational event is not appropriate. Special circumstances may arise in which orthopaedic surgeons may be required to learn new surgical techniques demonstrated by an expert or to review new implants or other devices on-site. In these circumstances, reimbursement for expenses may be appropriate.

EXPLANATION: The structure identified by the forceps is the radioscaphocapitate ligament. During a proximal row carpectomy, it is very important to identify and protect this ligament. Compromise of the ligament would result in ulnar translocation of the carpus and early failure of the proximal row carpectomy procedure. If the ligament is injured during surgery, immediate repair should be performed. Green and associates discuss the importance of the radioscaphocapitate ligament in stabilizing the carpus after this procedure is performed. Nakamura and associates compared 3-mm, 6-mm, and 10-mm radial styloidectomies, and only the 3-mm styloidectomy subsequently preserved carpal stability. Compromise of the radioscaphocapitate ligament occurred when larger portions of the radial styloid were excised. Distal radioulnar joint instability would result only from the disruption of the distal radioulnar joint stabilizers. Avascular necrosis would not occur, because the capitate receives its blood supply mainly from the palmar vessels. Finally, loss of active thumb IP flexion would not occur, because the flexor pollicis longus tendon would remain intact even if ligament compromise were to occur.

Both autograft and allograft have been used for complex acetabular reconstructions. They have been shown to be successful in the short term. However, graft resorption with collapse and subsequent cup loosening have occurred at high rates for both types of grafts, especially if reinforcement rings or cages are not used.

Poor survivorship of cemented sockets in young patients has led to the development of a variety of cementless designs. Of these, smooth metal-backed sockets have not performed as well as porous-coated designs. Threaded metal-backed sockets showed a 6% to 25% revision rate secondary to aseptic loosening at a mean follow-up of 4.5 to 6 years. Despite some early failed designs, cementless porous-coated metal-backed sockets have shown the best survivorship in long-term studies.

DISCUSSION: Contralateral total hip arthroplasty in patients with hip fusions results in a 40% higher rate of mechanical failure and loosening. During gait, motion of the contralateral hip is increased and more time is spent bearing weight on that hip. In patients with hip fusions, gait efficiency is only 53%, with a greater rate of oxygen consumption. REFERENCES: Garvin KL, Pellicci PM, Windsor RE, et al: Contralateral total hip arthroplasty or ipsilateral total hip arthroplasty in patients who have long-standing fusion of the hip. J Bone Joint Surg Am 1989;71:1355-1362. Gore DR, Murray MP, et al: Walking patterns of men with unilateral surgical hip fusion. J Bone Joint Surg Am 1975;57:759-765. Romness DW, Morrey BF: Total knee arthroplasty in patients with prior ipsilateral hip fusion. J Arthroplasty 1992;7:63-70.

Paletta and Laskins performed a retrospective study of the results of TKA with cement in 22 patients who had a previous patellectomy. Nine of the patients had insertion of a posterior cruciate ligament-substituting implant. Thirteen patients had insertion of a posterior cruciate ligament-sparing implant. The 5-year postoperative knee scores were 89 for the posterior cruciate ligament-substituting knee versus 67 for the posterior cruciate ligament-sparing knee (P < 0.01). The patella functions to increase the lever arm of the extensor mechanism and to position the quadriceps tendon and the patellar ligament roughly parallel to the anterior cruciate ligament and posterior cruciate ligament, respectively. The patellar ligament thereby provides a strong reinforcing structure that functions to prevent excessive anterior translation of the femur during flexion of the knee. The absence of the patella results in the patellar ligament and the quadriceps tendon being relatively in line with one another. After a patellectomy, the resultant quadriceps force is no longer parallel to the posterior cruciate ligament. This results in loss of the reinforcing function of the patellar ligament. The authors believe this loss of reinforcing function may place increased stresses on the posterior cruciate ligament and posterior aspect of the capsule, which may result in stretching of these structures over time. They found a high rate of anteroposterior instability, a high prevalence of recurvatum, and a high rate of loss of full active extension compared with passive extension in the posterior cruciate ligament-sparing group, which supports their theory.

Proximally coated femoral components were conceived in response to the proximal stress shielding seen with extensively coated total hip stems, but initial patient studies showed problems with osteolysis, thigh pain, and stability. However, Mont and Hungerford now report that second-generation devices that have been in use more than 5 years clinically have shown very low aseptic loosening rates (1% to 3%), and patients report less thigh pain (less than 5% in most studies). These results can be attributed to improved geometry, instruments, and technique, which ensure initial implant stability. The authors suggest that proximal coating must be circumferential to seal the diaphysis from wear debris, and they note that the concept of proximal coating for cementless femoral stems seems viable as long as the twin requirements of circumferential coating and rigid initial stability are realized.

Iliopsoas impingement is a potential cause of persistent groin pain after a total hip arthroplasty. This patient’s history gives groin pain with resisted hip flexion and during activities that require this level of function. The radiographs depict an acetabular component with substantial retroversion. Typical options for the management of iliopsoas tendon impingement include injections, tenotomy, and acetabular revision. Recently, Chalmers and associates reported more predictable groin pain resolution with 8 mm or more of anterior acetabular component when overhang was revised. The radiographs clearly show more retroversion, with a cup prominence of more than 8 mm anteriorly. MRI with MARS could potentially help in the diagnosis of this impingement but would not help in management. An ultrasound-guided injection would need to be administered into the iliopsoas tendon sheath to be of help and, in this case, would likely be performed for diagnostic purposes due to the extreme anterior overhang. Option D would be useful for mild cases of iliopsoas impingement but likely would not help much in this more extreme case.

This situation represents a definitively and chronically infected knee replacement. Antibiotic therapy alone might suppress the infection but would not eradicate it. Debridement and polyethylene exchange would be appropriate treatment for an early postoperative infection. The treatment of choice is to perform a two-stage debridement and reconstruction. Although not among the listed choices, an aspiration or culture could be done presurgically and might help clinicians identify the best antibiotics to treat the condition. Antibiotic selection would not affect the need for the two-stage reconstruction, however.

This patient has a neuropathic knee caused by neurosyphilis, as shown by the joint destruction on the radiographs, with a lack of pain and a positive RPR test. He has a low-demand job and would be best treated with a hinged knee arthroplasty to provide stability for his knee.

The treatment of choice for a late hematogenous infection is two-stage resection arthroplasty and reimplantation, with parenteral antibiotics prior to reimplantation. This is particularly true when septic loosening has occurred as in this patient. Open irrigation and debridement with polyethylene exchange has been used successfully when the duration of symptoms is 3 weeks or less. Long-term suppressive antibiotics are most commonly used when the patient’s medical condition precludes further surgery. Delayed reimplantation has been shown to be superior to immediate reimplantation in multiple studies. Little data support the use of arthroscopic irrigation and debridement.

DISCUSSION: Given a well-fixed acetabular metal shell and a localized osteolytic lesion, good outcomes can be expected from liner revision in this clinical scenario with retention of the metal socket, assuming no damage to the components or other unexpected findings arise during revision surgery. Here, complete cup revision is not warranted, considering the appropriate implant position. Beaulé and associates reviewed 83 consecutive patients (90 hips) in whom a well-fixed acetabular component was retained in a clinical scenario such as the one described. No hip showed recurrence or expansion of periacetabular osteolytic lesions. If the metal cup is unstable, acetabular component revision may be indicated.

DISCUSSIONBased on the fact that the fracture is occurring around the stem (type B) and the stem is clearly loose (type B2), the appropriate treatment is removal of the in situ stem (which is loose), ORIF of the femur (cerclage wires, cables, or a plate would be acceptable), and insertion of a longer revision stem (a tapered fluted modular titanium or fully porous coated cylindrical stem) to bypass the fracture. All other responses are incorrect because they provide inappropriate treatment options for a Vancouver B2 fracture.

DISCUSSION: The patient has an acute postoperative fracture of the proximal femur with subsidence. It is also common that the stem retroverts relative to the femur. It is most often seen in proximally porous coated stems within 90 days of surgery; one paper found it to occur 0.7% of the time in modern implants. There is always a debate whether this is a missed intraoperative fracture, or a new fracture that has resulted from an event of increased hoop stresses. Removal of the primary stem, placement of a diaphyseal engaging stem (most frequently a tapered-fluted stem), and cabling of the fracture is the most successful treatment.

Recent studies have shown a high rate of waste of autologous blood. Therefore, the Committee does not recommend autologous blood donation for procedures that carry a transfusion risk of 10% or less.