Management of the patella in revision total knee arthroplasty

Problems with the patellofemoral joint comprise the most common complication in primary and revision total knee arthroplasty (TKA). The difficulties can range from instability and anterior knee pain at one end of spectrum of severity, to fracture and extensor mechanism disruption at the other end. These complications are generally higher in revision TKA due to compromised bone stock and blood supply. Despite the particular challenges posed by the bone-deficient patella, reasonable results can be achieved.     

The patella in total knee arthroplasty.

Controversy persists as to whether the patella should be resurfaced in total knee arthroplasty. Can the good results of patellar cartilage against the metal femoral component be expected to endure? Attention to technique can be expected to reduce some of the complications of resurfacing, notably fracture, rupture, and instability. Component breakage results from metal-backed designs, and the causes of patellar clunks have not been fully understood.     

Management of recurrent dislocation of the patella following total knee arthroplasty.

Fifteen knees with patellar dislocation after total knee arthroplasty had realignment of the extensor mechanism using a modification of the Trillat procedure. The onset of dislocation occurred on average 4.7 months from the time of surgery. After total knee arthroplasty the patients had an average range of motion of 109 degrees. All patients had medialization of the tibial tubercle and lateral release. No patient had a recurrent dislocation after a minimum 2-year follow-up period. The average knee score was 82 and the average flexion arc was 112 degrees. All but one of the osteotomies healed uneventfully.     

Technical considerations of total knee arthroplasty after proximal tibial osteotomy

Forty-five total knee replacements in forty-one patients who had continued to have progressive osteoarthritis after a proximal tibial osteotomy were evaluated prospectively. There were 51 per cent excellent, 29 per cent good, 4 per cent fair, and 16 per cent poor results after a minimum follow-up of two years. The resection of tibial bone that was produced by the osteotomy could not be related causally to the fair or poor clinical results that were found after arthroplasty. Radiographic study, however, showed that 80 per cent of the knees had patella infera before the arthroplasty, which may contribute to altered biomechanics of the patellofemoral joint of the arthroplasty. The procedure for total knee replacement is made more difficult by the previous osteotomy, and a custom-made prosthesis may be required. The clinical results that were obtained in this series are similar to those for the revision total knee arthroplasties that have been done at this institution, but they were not as satisfactory as those that were obtained after primary total knee replacement. Our results should be considered when a surgeon compares the advantages and disadvantages of proximal tibial osteotomy with those of total knee arthroplasty for an older patient who has unicompartmental osteoarthritis of the knee.     

全膝关节置换术中髌骨处理

全膝关节置换术中是否进行髌骨置换仍有争论,术后膝前疼痛及髌股关节并发症是争论的焦点.膝前疼痛是多种因素共同作用的结果,不能简单地归咎为髌骨置换与否.全膝关节置换时是否置换髌骨应考虑原发病、病变程度、假体类型及患者活动量和体重等诸多因素.如果行髌骨置换,精湛的外科技术、合适的假体是全膝关节置换术后髌股关节并发症减少的关键;如果不行髌骨置换,患者的筛选标准是保证手术疗效的关键.     

Asymmetric patella resurfacing in total knee arthroplasty

Three hundred consecutive primary, cemented, condylar total knee arthroplasties (TKAs) were reviewed for the presence of asymmetric patella resurfacing using a postoperative Merchant or sunrise patellar radiograph. Twenty-one knees in 14 patients were found to have the patella asymmetrically resurfaced. Asymmetric resurfacing typically involved the inadvertent preferential resurfacing of the lateral facet with underresection of bone from the medial patellar facet. All patients underwent follow-up for a minimum of 5 years, with a mean follow-up of 7.5 years. Of the 21 knees, 3 revisions were required for patellar complications. One patellar component was loose on radiographs and there was marked patellofemoral pain in 6 knees. Overall, 11 of 21 knees (52%) underwent revision or were recommended for revision for patellar complications or had anterior knee pain that limited activities. Inadvertent asymmetric patella resurfacing using the kinematic condylar implant adversely affects the outcome after TKA.     

Medialization of the patella in total knee arthroplasty

Patellar complications of total knee arthroplasty remain the most common cause of pain and reoperation. Laboratory studies have suggested that medialization of the patella will improve tracking of the patella on the trochlea of the femoral component. The purpose of this study was to determine if clinical medialization of the patellar component on the patellar bone would improve tracking of the patella as demonstrated radiographically. Sixty-two knees were randomized so that 31 knees had a centrally placed patellar component and 31 had the patellar component placed on the medial two thirds of the patellar bone. There was no difference between the two groups with respect to either clinical or radiographic results in the first year after surgery. There was no improvement compared with previous reports in the incidence of tilt and displacement. The one improvement was a reduction in the incidence of lateral release. Thus, consequences of lateral release such as postoperative morbidity, avascular necrosis of the patella, and stress fracture of the patella can be avoided. It is recommended that the patellar component be placed on the medial two thirds of the patella to reduce the occurrence of lateral release. Tracking of the patella during surgery can be assessed using a single suture placed at the superior pole of the patella, and this technique in combination with the no-thumbs test provides an additional means of evaluation for patellar tracking.     

Effect of patella thickness on patella strain following total knee arthroplasty

Patellar complications following total knee arthroplasty (TKA) have begun to emerge as a major cause of failure. In an effort to understand some of the mechanical factors that might contribute to patellar component failure, a biomechanical study was performed. Quadriceps force and anterior patellar strain were measured during dynamic flexion in 10 fresh, paired human cadaver knee joints. First, tests were performed in the intact knee, followed by either posterior cruciate ligament (PCL) retention or sacrifice of TKA without patellar resurfacing. Tests were then performed following patellar resurfacing with an overly thick, optimum and thin, bony patella. Patellar strain increased in each specimen (with flexion angles of up to 80 degrees), was most pronounced as the bony patella became thinner, was closest to the intact knee when the patella was not resurfaced, and was unaffected by PCL retention or sacrifice. Patellar osteotomy, resulting in a bony patellar thickness of less than 15 mm, resulted in significantly increased strain. TKA systems should include instrumentation that allows precise restoration of overall patellar thickness while maintaining a bony patellar thickness of at least 15 mm.     

One-peg versus three-peg patella component fixation in total knee arthroplasty.

In many designs of total knee arthroplasty, the patella with one central peg has been replaced by a patella with three small pegs for cement fixation. There have been recent reports of failure of this design. This is a prospective, consecutive study of two types of patella component fixation in 228 posterior-stabilized knee arthroplasties done by one surgeon. A central peg all-polyethylene component was used for 84 consecutive knees in 63 patients (Group A) and a three-peg patella was used for the next 144 consecutive knees in 99 patients (Group B). The mean followup was 6.7 years (range, 2-10 years) for Group A and 3.5 years (range, 2-6 years) for Group B. Except for the patellar component fixation, all knees had the same posterior-stabilized prosthesis using a specific protocol for patellar resurfacing. No patient required reoperation for a patellofemoral complication. The prevalence of patella fracture was higher in Group A, 4.7% (four knees), compared with 2.1% (three knees) in Group B, but this difference was not statistically significant. The presence of anterior knee pain referable to the patella was 7.1% (five patients, six knees) in Group A (one patient with two knees had severe anterior knee pain) and 9% (13 knees in 13 patients) in Group B. There was no patella clunk syndrome, subluxation, or fracture of a fixation peg in either group. With this specific protocol for patella resurfacing, there was a higher rate of complications with the one central peg patella (4.7%) than with the three-peg patella (2.1%), but this did not reach statistical significance. The results do not support an increased risk of component failure with this three-peg patella design, but do not, at this length of followup, show any significant advantage of three-peg fixation.     

Fracture of the patella following total knee arthroplasty

The charts of 21 patients (22 knees) with significant radiographic changes of the patella after total knee arthroplasty were reviewed. The average patient age was 73 years, and average follow-up after arthroplasty was 7.3 years. Lateral release, fat pad excision, quadriceps tendon release, and previous surgery were implicated in the etiology of fracture of the patella. Five cases had type 1 pattern (sclerosis, fragmentation, and no fracture), 5 cases had type 2 pattern (undisplaced fracture and fragmentation), and 12 cases had type 3 pattern (displaced fracture and fragmentation). Type 1 and 2 patterns required no surgical treatment and were rated good to excellent according to the Hospital for Special Surgery Disability Score Sheet. Patients with a type 3 pattern who did not undergo surgery were rated poor to fair, while patients with a type 3 pattern who underwent surgical treatment (patellectomy, removal of the patellar component, or excision arthroplasty for infection) were rated good. Patellectomy is the treatment of choice for patients with displaced fractures of the patella. A classification system for the pattern of patellar changes is proposed.     

Fracture of the patella after total knee arthroplasty

Patellar fracture after knee arthroplasty was found in 11 patients (12 knees) during a 15-year period. Causes of this fracture include trauma, technical factors, and biophysical factors. The incidence of this infrequent complication was significantly increased after patella resurfacing and revision arthroplasty. Minimally displaced, non-comminuted fractures were immobilized, whereas displaced, comminuted fractures with loose patellar prostheses were treated operatively. At a mean follow-up period of 28 months, the average knee score was 75 points. The average arc of motion was 87 degrees, and six of the 11 patients have returned to their prefracture functional level. Treatment should be individualized on the basis of fracture displacement, comminution, and button fixation.     

Fractures of the patella after total knee replacement

Pateller fractures in association with total knee replacement are uncommon, but potentially a cause of an unsatisfactory clinical outcome. Patient, implant, and technical factors are important predisposing causes of these patellar fractures. Prevention is the best treatment. Important outcome criteria include the integrity of the extensor mechanism, patellar implant fixation, and anatomic location. Patients requiring operative intervention often have an unsatisfactory outcome.     

Technical considerations in replantation of total scalp avulsions.

Total scalp avulsions are devastating injuries and replantation is the best form of reconstruction. We present our experience of replantation of six totally avulsed scalps done between 1996 and 2004. All were technically successful, but one was lost in the post-operative period due to accidental shearing of the scalp during nursing care. A single team performed the surgery in all cases and the average operating time was 6 h. No vein grafts were used. Hair growth was satisfactory in all cases. None underwent formal nerve repair but there was adequate sensory recovery in all of them by 6-9 months. A small area of skin necrosis in the occipital area (three cases), telecanthus and epiphora (two cases) were the minor complications. The available Literature highlights the need for multiple teams to reduce the long operating time, the use of multiple vein grafts and the complexities involved. Since, they are rare injuries, gaining wide experience is difficult. In this article we offer recommendations in pre-op preparation, vessel identification, technique of anchoring the avulsed scalp prior to vessel anastomosis and post-op care to make this rare procedure quicker, easier and successful.     

A new concept for precise patella resection in total knee arthroplasty.

We developed a new patella-cutting guide that simplifies proper alignment and enables resection of the correct thickness of bone. This guide consists of a central shaft, two support frames, and a ring. The ring consists of upper and lower disks, with a slot between the disks. The central shaft and the lower disk have holes for fixation pins. The distance from the distal end of the central shaft to the lowest level of the slot is 8 mm. Bone of the same thickness as that of the patellar component can be automatically resected using this guide. A feeler gauge is inserted through the slot, and the periarticular region is felt. This procedure enables the guide to be set at the correct angulation. A laboratory study using fresh-frozen cadaver patella specimens and a clinical study showed that proper alignment and proper resection were achieved using this guide.     

Secondary patella resurfacing in painful non-resurfaced total knee arthroplasties

Purpose

In Norway, 19 % of revisions of non-resurfaced total knee arthroplasties done for knee pain between 1994 and 2011 were Secondary Patella Resurfacing (SPR). It is, however, unclear whether SPR actually resolves the pain. The aim was to investigate prostheses survival and clinical outcomes following SPR.

Method

A total of 308 knees (301 patients) with SPR were used to assess implant survival, and a sub-cohort (n?=?114 out of 301 patients) with Patient Reported Outcome Measures (PROMs) data were used to assess the clinical outcomes. The EuroQol (EQ-5D), the Knee Injury and Osteoarthritis Outcome Score, and Visual Analogue Scales on satisfaction and pain were used to collect PROM data. Outcomes were analysed by Kaplan-Meier, Cox regression, and multiple linear regression.

Results

The five- and ten-year Kaplan-Meier survival percentages were 91 % and 87 %, respectively. Overall, 35 knees were re-revised at a median follow-up of eight years and pain alone (10 knees) was the main cause of re-revision. Younger patients (<60 years) had nearly nine times higher risk of re-revision compared to older patients (>70 years) (RR?=?8.6; p?<?0.001). Mean EQ-5D index score had improved from 0.41 (SD 0.21) preoperative to 0.56 (SD 0.25) postoperative following SPR. A total of 63 % of patients with PROM data were satisfied with the outcomes of SPR.

Conclusion

The long-term prostheses survival following SPR was satisfactory, although not as good as for primary knee replacement. Patients’ health related quality of life improved significantly following SPR. Still, more than a third of patients with PROMs data were dissatisfied with the outcomes of the SPR procedure.

     

Secondary resurfacing of the patella in mobile-bearing total knee arthroplasty

OBJECTIVE: We aim to evaluate the impact of secondary patellar resurfacing in patients with patellar-related anterior knee pain who have undergone a mobile-bearing primary knee arthroplasty without resurfacing. MATERIALS: A total of 2950 primary Low Contact Stress (DePuy, Warsaw, Ind) mobile-bearing knee arthroplasties without patellar resurfacing were carried out between March 1992 and March 2003. Thirteen patients (0.4%) underwent secondary patellar resurfacing for patellar-related anterior knee pain. The mean age of the patients was 67.8 years. There was a mean time of 28 months to the secondary resurfacing procedure. RESULTS: Only 4 patients had an unequivocal improvement in their symptoms at a mean follow-up of 45 months (range, 3-92 months). No morbidity was noted from the procedure. CONCLUSION: The success rate of secondary patellar resurfacing is poor and patients should be counseled carefully.