Minimally invasive Oxford medial unicompartmental knee arthroplasty

We present the peak outcome results of the Oxford medial unicompartmental arthroplasty through a minimally invasive surgical incision. This prospective study included 78 Oxford medial unicompartmental knee replacements in 68 patients. At the 2 year review the patients achieved a mean Oxford Knee Score of 38.3. This was not significantly different to the 2 year results of the phase 2 Oxford knee carried out using a standard parapatellar approach when patients achieved a mean OKS of 36.0. Four unicompartmental knee replacements required revision for unexplained pain, deep infection, aseptic loosening and bearing dislocation. Minimally invasive joint replacement is attractive to both patients and surgeons, but is technically demanding with complications inherent to limited access.     

Joint line restoration after revision total knee arthroplasty.

In 99 patients, 107 knee replacements were revised in two centers by two surgeons using a single revision total knee arthroplasty system. A retrospective radiographic review of joint line position before and after revision total knee arthroplasty was made, and compared with the joint line position before primary knee arthroplasty. Prospectively collected Knee Society Clinical Rating Scores were correlated with radiographic findings. The joint line position in unreplaced knee replacements averaged 16 mm, and the joint line position in knee replacements before revision surgery averaged 17 mm. The joint line was elevated by the revision total knee arthroplasty in 85 of 107 knees (79%). After the revision total knee replacement, the joint line elevation averaged 24 mm. The Knee Society Clinical Rating Score after revision surgery averaged 131 points. If the joint line position was elevated more than 8 mm, the Knee Society Clinical Rating Score averaged 125 points, if the joint line was elevated less than 8 mm, the score averaged 141 points. Joint line elevation after revision total knee replacement is a problem. Excessive elevation may result in worse clinical outcomes. Distal femoral augments should be used more often and with greater thicknesses. Standard implants used for revision surgery should have increased distal dimensions.     

The use of an articulating spacer in the management of infected total knee arthroplasties

Eleven infected total knee arthroplasties underwent revision using an articulating spacer comprising a total condylar component and meniscal polyethylene insert cemented in place using antibiotic-loaded cement. Only 1 case required subsequent rerevision for infection, 2 were revised for pain, 6 remain in situ, and 2 patients have died with their spacers in situ. Average Knee Society clinical rating for the spacers left implanted is 167 at an average of 65 months. This articulating spacer appears not to require mandatory second-stage surgery, although should this prove necessary, then it is relatively straightforward to perform.     

Midterm results of cemented Press Fit Condylar Sigma total knee arthroplasty system

PURPOSE: To evaluate the midterm results of 50 patients who underwent total knee replacement using Press Fit Condylar (PFC) Sigma system. METHODS: We retrospectively reviewed 87 consecutive cases (50 patients with 37 bilateral cases) of PFC Sigma total knee replacement performed between January 1998 and December 1999. Patients were evaluated clinically and radiographically by an independent observer. The American Knee Society Score, Oxford Knee Score, and Knee Society radiographic assessment were used to rate knee function and to determine the satisfaction level of each patient. RESULTS: The mean age of the patients at the time of operation was 65 years (range, 41-85 years). The mean follow-up period was 5.4 years (range, 4.5-6.4 years). 44 patients (79 knees) were available for follow-up, 3 patients (3 knees) were lost to follow-up, and 3 patients (5 knees) died of unrelated causes. At the final follow-up, the mean Oxford Knee Score was 22. Using the American Knee Society Score, 88% of the knees were rated excellent, 4% good, 2% fair, and 6% poor. Five knees required revision surgery, the indications being infection in 4 knees and aseptic loosening in one knee. The survival rate of the implants was 94% at 6 years. CONCLUSION: The PFC Sigma total knee arthroplasty system has demonstrated good midterm results at our institution.     

Tibial tubercle osteotomy in septic revision total knee arthroplasty

Purpose

The incidence of revision knee arthroplasty for infection is increasing and the required surgical approach for the revision is a challenge for surgeons. Extensile approaches are frequently used when it is impossible to evert the extensor mechanism. The aim of this paper is to report our experience with tibial tubercle osteotomy (TTO) and the functional results in patients who underwent a two-stage revision due to prosthesis infection.

Methods

Twenty-six patients underwent a TTO as a surgical approach in the second stage of revision for infection. The patients were clinically assessed by means of functional scales (the Knee Society Score and WOMAC) and X-rays.

Results

The TTO healed without complications in 22 patients (84.6 %) and the average length of follow-up was 3.4 years. Non-union was observed in two patients. One patient presented an extension lag of 5°. A total of 23 patients (88.4 %) were free from infection. Twenty-five patients (96.1 %) had better scores on the Knee Society Score and WOMAC after the procedure.

Conclusions

In patients undergoing the second stage of revision total knee arthroplasty for infection, the TTO approach provides a large operating field. This enables surgeons to withdraw spacers and position new implants without damaging the extensor mechanism of the knee or altering the postoperative rehabilitation process. The complications that have been reported as a result of this procedure could be reduced by performing a meticulous surgical technique.

Level of evidence

Retrospective case series, Level IV.     

Articulating versus static spacers in revision total knee arthroplasty for sepsis. The Ranawat Award

Antibiotic laden spacer blocks frequently are used to treat an infected total knee arthroplasty. Static spacer blocks make exposure at reimplantation difficult secondary to quadriceps shortening. Unexpected bone loss attributable to migration of the spacer block also has been reported. To avoid these problems, a temporary articulating molded implant made of antibiotic cement was used in a consecutive series. The authors sought to determine whether its use would affect the reinfection rate, improve functional results, or prevent bone loss compared with static spacers. Twenty-five patients were treated with static nonarticulating spacers. Since 1996, 30 patients have been treated with tobramycin-laden articulating spacers. The knee arthroplasties in three patients treated with a static spacer became reinfected (12%). The knee arthroplasty in one patient with an articulating spacer became reinfected (7%). Fifteen of the 25 patients with static spacers had unexpected bone loss between stages. No appreciable bone loss could be measured in the patients who received articulating spacers. The average Hospital for Special Surgery score was 83 points in the patients with static spacers and 84 points for the patients with articulating spacers. Range of motion at final followup averaged 98 degrees in the patients who received static spacers and 105 degrees in the patients who received articulating spacers. Articulating spacers seem to facilitate reimplantation of infected total knee arthroplasty without additional risk of infection. Unexpected bone loss is no longer a concern with this two-stage technique. Articulating spacers offered no functional advantage over static spacers in this study group.     

The natural history of severe osteoarthritis of the knee in patients awaiting total knee arthroplasty

The disabling symptoms of osteoarthritis of the knee can be dramatically improved with joint replacement. The aim of this study was to examine the change in pain and physical function that occurs in patients with osteoarthritic knees awaiting total knee replacement. Data was collected prospectively from a cohort of 124 consecutively recruited patients at three stages of assessment over a mean of 24 months (range 9–32 months). The patients were assessed at the time of referral by the general practitioner, when first assessed by the orthopaedic consultant, and just before surgery. At each visit, the patients were examined and the American Knee Score and Oxford Knee Score completed by the patient. The function element of the American Knee Score deteriorated significantly from the time of referral till the time of first orthopaedic consultation (P=0.005) and also from the time of referral to the time of surgery (P=0.006). The pain element of the American Knee Score improved from the time of referral till the time of orthopaedic assessment (P=0.011). The change in Oxford knee scores between the time the patient was put on the waiting list and the time of surgery was not statistically significant (P=0.30). Our study shows that for patients referred with severe osteoarthritis of the knee, both the American Knee Scores and Oxford Knee Scores deteriorate significantly prior to surgery, although most of this change is not during their time on the waiting list. The time from referral by the general practitioner (GP) to orthopaedic assessment by the consultant was l.8–14.2 months (average 9.8 months) and from the time of orthopaedic assessment, i.e. when seen by the consultant and placed on the waiting list to the time of surgery was 9.1–22 months (average 13.3 months). We have shown that the pain and functional elements of the American Knee Score behave independently to the total score. This research therefore questions the current emphasis on surgical waiting times instead of patient symptoms and physical function in determining the timing of surgery.     

Lateral unicompartmental knee replacements: early results from a District General Hospital

Lateral unicompartment knee replacements are performed infrequently in the United Kingdom. This study evaluates the experience of two knee surgeons in a District General Hospital for all lateral unicompartmental arthroplasties performed between October 2007 and August 2011. Two different implants were used in this time period, the Oxford domed and the Zimmer fixed-bearing system. Twenty-seven procedures were completed in this time span (15 Oxford domed and 12 Zimmer fixed bearing), all of which once completed were followed up and 21 patients completed an Oxford knee score. Average Oxford knee scores were 36.6 (95 % CI 29.0–44.2) for the Oxford domed prosthesis and 28.6 (19.8–37.5) for the Zimmer fixed-bearing prosthesis (p = 0.15). One patient with an Oxford domed prosthesis required revision for bearing dislocation. The follow-up Oxford knee scores support the use of this technique as an alternative to total knee replacement but with no significant difference in functional outcome. Our results, however, may encourage a more cautious approach to the use of a mobile-bearing prosthesis in favour of a fixed-bearing prosthesis.     

Unicompartmental knee replacement. A minimum 15 year followup study.

One hundred forty Marmor cemented unicompartmental knee replacements were inserted in 103 patients between 1975 and 1982. Fifty-two patients were women and 51 were men. One hundred twenty-five were medial compartment knee replacements and 15 were lateral knee replacements. At minimum 15 year followup 34 patients with 48 knee replacements were living; only four patients with four knee replacements were lost to followup. Average preoperative and final followup Hospital for Special Surgery knee scores were 57 and 82 points, respectively for the knees of living patients. Average preoperative and final followup Knee Society clinical and Knee Society functional scores were 31 and 42, and 85 and 71 points, respectively. For all knees, 10.2% (14 knees) were revised [4.4% (six knees) for tibial loosening, 5.1% (seven knees) for disease progression, and .7% (one knee) for pain]. For patients living 15 years, 12.5% (six knees) were revised [2.1% (one knee) for tibial loosening, and 10.4% (five knees) for disease progression]. Revision for failure of fixation of these unicompartmental replacements was comparable with that reported for fixed bearing total knee replacement. Disease progression (46%; 62 of 136 knees) and tibial subsidence with wear (10.4%; 15 of 136 knees, five of which required revision) were the major long term problems in this group of patients.     

Revision knee arthroplasty using a distal femoral replacement prosthesis for periprosthetic fractures in elderly patients

Purpose

Distal femoral periprosthetic fractures above a total knee replacement in elderly patients are technically challenging to treat. Bone quality is often poor, the fractures comminuted, and post-operative mobilisation is difficult. This study assesses the clinical, radiological and functional outcome of revision knee distal femoral replacement (DFR) in these fractures.

Methods

We identified 14 patients over 70 years of age (70–94) who underwent DFR for periprosthetic fractures above a knee replacement. All the 14 fractures were classified as Su type III. Clinical and radiological records were retrospectively reviewed. The mean of clinical follow-up was 27 months (8–46). Functional outcome was assessed using Oxford Knee Score and EQ-5D (UK English Version) score at a mean time of 35 months (20–65). The Knee Society patient category score was also evaluated.

Results

The median post-operative knee flexion was 100° (range 90°–135°). Nine patients (64%) returned to their pre-fracture level of mobility or better. The median post-operative Oxford Knee Score was 27 (range 4–40). The median EQ-5D was 11 (range 6–12). Cognitive impairment negatively impacted the functional outcome in four patients. One patient died early post-operatively, and two patients had complications.

Conclusions

DFR led to satisfactory outcome in our patients with a relatively low complication rate. In our experience, revision knee distal femoral replacement is an appropriate method to treat elderly patients who sustained periprosthetic Su et al. type III distal femoral fractures in association with poor bone stock, caused by osteoporosis and/or comminution.

     

Minimally invasive Oxford phase 3 unicompartmental knee replacement: results of 1000 cases

This prospective study describes the outcome of the first 1000 phase 3 Oxford medial unicompartmental knee replacements (UKRs) implanted using a minimally invasive surgical approach for the recommended indications by two surgeons and followed up independently. The mean follow-up was 5.6 years (1 to 11) with 547 knees having a minimum follow-up of five years. At five years their mean Oxford knee score was 41.3 (sd 7.2), the mean American Knee Society Objective Score 86.4 (sd 13.4), mean American Knee Society Functional Score 86.1 (sd 16.6), mean Tegner activity score 2.8 (sd 1.1). For the entire cohort, the mean maximum flexion was 130° at the time of final review. The incidence of implant-related re-operations was 2.9%; of these 29 re-operations two were revisions requiring revision knee replacement components with stems and wedges, 17 were conversions to a primary total knee replacement, six were open reductions for dislocation of the bearing, three were secondary lateral UKRs and one was revision of a tibial component. The most common reason for further surgical intervention was progression of arthritis in the lateral compartment (0.9%), followed by dislocation of the bearing (0.6%) and revision for unexplained pain (0.6%). If all implant-related re-operations are considered failures, the ten-year survival rate was 96% (95% confidence interval, 92.5 to 99.5). If only revisions requiring revision components are considered failures the ten-year survival rate is 99.8% (confidence interval 99 to 100). This is the largest published series of UKRs implanted through a minimally invasive surgical approach and with ten-year survival data. The survival rates are similar to those obtained with a standard open approach whereas the function is better. This demonstrates the effectiveness and safety of a minimally invasive surgical approach for implanting the Oxford UKR.     

A rotating-hinge knee replacement for malignant tumors of the femur and tibia

We evaluated the 2- to 7-year results of a rotating-hinge knee replacement after excision of malignant tumors of the knee joint. There were 25 distal femoral and 7 proximal tibial replacements. The 5-year prosthetic survival for distal femoral replacements was 88%, compared with 58% for proximal tibial replacements. Seven patients underwent prosthetic exchange: 1 for aseptic loosening, 2 for wound slough and perioperative infection, and 4 for articulating component failure. One patient underwent above-knee amputation owing to skin necrosis. The median functional scores at the latest follow-up were 27 by the International Society of Limb Salvage evaluation system and 80 by the Hospital for Special Surgery Knee Score system. This implant is a promising choice for joint reconstruction after excision of tumors at the knee joint.     

Perceptions of outcomes after unicompartmental and total knee replacements

An independent measurement of the quality of outcome of 31 consecutive Oxford medial unicompartmental knee replacements in 28 patients and 130 total knee replacements in 104 patients performed between 1993 and 1997 is reported. The indications for surgery were anteromedial osteoarthritis for unicompartmental replacement and more extensive osteoarthritis for total knee replacement. All patients were treated by one surgeon. As a validated outcome measure of knee function, the Oxford 12-item knee questionnaire showed identical outcome in both groups with a mean score of 36.5 (maximum possible, 48). Neither the pain nor the functional outcomes were significantly different, although patients receiving unicompartmental replacement were better able to descend stairs. Two patients needed revision surgery in the unicompartmental replacement group compared with only one patient in the total knee replacement group. The femoral component of two unicompartmental replacements showed radiologic signs of loosening. The tibial component of one total knee replacement appeared loose, but the patient had no symptoms. In comparison with total knee replacement, implantation of meniscal bearing unicompartmental replacement technically is demanding and unforgiving. However, revision of a failed Oxford unicompartmental replacement is easier than revision of a failed total knee replacement, and the authors recommend this device for younger patients in whom one could expect a total knee replacement to fail within their lifetime.     

Custom-made Articulating Spacer in Two-stage Revision Total Knee Arthroplasty. An Early Follow-up of 14 Cases of at Least 1 Year After Surgery

Total knee replacement (TKR) infection represents only a small percentage of all the potential complications in joint replacement, but one that can lead to disastrous consequences. Two-stage revision, which has been proven to be the most effective technique in eradicating infection, includes prosthesis removal, positioning of an antibiotic-loaded spacer, and systemic antimicrobial therapy for at least 6 weeks. It has been suggested that there is better performance in terms of range of motion, pain, extensor mechanism shortening, and spacer-related bone loss if articulating spacers are used instead of fixed spacers. In this paper, we describe our results in two-stage revision of infected total knee arthroplasty with a minimum follow-up of 12 months on 14 patients treated by antibiotic-loaded custom-made articulating spacer as described by Villanueva et al. (Acta Orthop 77(2):329–332, 2006). The mean flexion achieved after the second stage of the revision was 120°, ranging from 97° to 130°. The mean Hospital for Special Surgery score was 84. At 1 year after surgery, none of the knees showed any evidence of recurrence of the infection. Articulating spacers are a suitable alternative to fixed spacers with good range of motion after reimplantation and effectiveness against total knee replacement deep infections.     

Distal femoral replacement in periprosthetic fracture around total knee arthroplasty

Introduction

Total knee arthroplasty is a common orthopaedic procedure in the UK; consequently, revision surgery and periprosthetic fractures are increasing in incidence. Strategies for management of these cases include non-operative strategies, internal plate fixation and revision of the distal femoral component. One under-reported practice is to perform distal femoral replacement in cases with poor distal femoral bone stock.

Materials and methods

The department's electronic database was searched for all patients undergoing revision of total knee arthroplasty. From these, all patients having distal femoral replacement for periprosthetic fracture around the distal femoral component using the Stryker Global Modular Replacement System (GMRS) implant were filtered. A retrospective analysis of the patient notes was performed to examine the patient demographics, surgical factors and postoperative complications. Postoperative scores were performed for these patients.

Results

From 2005 onwards, 11 patients (mean age 81 years, range 61–90 years) had their implants revised with a distal femoral replacement for periprosthetic fracture with associated poor bone stock. Follow up was for a mean of 33 months (range 4–72 months). One of these patients died of causes unrelated to their operation. Of the rest, all implants survived without the need of re-operation. The mean postoperative Oxford Knee Score for these patients was 22.5 (range 5–34).

Conclusions

Distal femoral replacement for patients with fracture around a total knee arthroplasty has been performed in our department with few complications and acceptable functional outcomes. It is a technically challenging operation and it should be a salvage procedure reserved for patients with poor bone stock and low demands where other methods of fixation are not suitable.

Level of evidence

IV.     

Long-term clinical results of the Oxford medial unicompartmental knee arthroplasty

The purposes of this study were to investigate the mode of failure and survivorship of an independently performed series of medial Oxford unicompartmental knee arthroplasties. The study included 43 knees in 40 patients with a mean follow-up of 14.88 years: 13 knees (11 patients) had revision surgery (30%), and ten patients required conversion to total knee prosthesis. The mean International Knee Society (IKS) scores at the time of the revision were 145.52 [standard deviation (SD): 39.90, range: 167–200]. The overall alignment of the knee was restored to neutral, with a hip-knee-ankle (HKA) angle average of 178° (SD: 3.21°, range: 170–186°). Survivorship, as defined by an endpoint of failure for any reason, showed that the survival rate at five years was 90%, at ten years 74.7% and at 15 years 70%. Excluding inappropriate patient selection and surgeon-associated failures, our survival analysis plot is much improved: survivorship at five years is 94.5%, at ten years 85.7% and at 15 years 80.4%. The Oxford meniscal bearing arthroplasty offers long-term pain relief with good knee function. Unfortunately, we demonstrated a high complication rate, with some of the failures encountered indicating that the surgical technique is very demanding.     

Short‐term Follow‐up of Antibiotic‐loaded Articulating Cement Spacers in Two‐stage Revision of Infected Total Knee Arthroplasty: A Case Series

Objective

Infection of total knee arthroplasty (TKA) is a rare but devastating complication. Two‐stage revision is an effective treatment for late infected TKA. This study aimed to assess the short‐term results of two‐stage revision using articulating antibiotic‐loaded spacers.

Methods

Twenty‐five patients (10 men and 15 women) were diagnosed with late infections after TKA and treated with two‐stage revision from April 2006 to August 2010; 19 of these patients had TKA for osteoarthritis and 6 for rheumatoid arthritis. Median age was 64.9 (range, 56–83) years. In the first‐stage surgery, the prosthesis and all bone cement was removed. After thorough debridement, bone cement with vancomycin and tobramycin was put into a die cavity and made into temporary femoral and tibial spacers, respectively. In the cases of good knee range of motion, the temporary spacers were affixed to the bone surface using the same antibiotic bone cement. In the second surgery, gentamycin Refobacin Bone Cement with vancomycin was used to fix the prosthesis. After two‐stage revision, patients were followed up clinically and radiologically at 1, 3, and 6 months, and then annually. Knee Society Score (KSS), knee function score, knee pain score, and knee range of motion (ROM) were assessed.

Results

Among the group, all spacers were easily removed, and bone defect degree showed no obvious change compared with pre‐implant, 24 (96%) patients had been debrided once, and 1 patient had been debrided twice before reimplant prosthesis. Mean follow‐up was 64.2 (range, 52–89) months. There was no infection recurrence at final follow‐up. Compared with preoperative data, the KSS (66 [59, 71], 83 [80, 88] vs 46 [43, 57], P < 0.01), knee function score (43 [42, 49], 78 [73, 82] vs 32 [25, 37], P < 0.01), knee pain score (34 [33, 37], 42 [40, 45] vs 18 [16, 23], P < 0.01), and knee ROM (92° [86°, 96°], 94° [90°, 98°] vs 78° [67°, 86°], P < 0.01) were all improved during follow‐up and at final visit. Three patients experienced complications in the interval period: one case had knee dislocation, one had knee instability, and one had a chip in the femoral component of the spacer.

Conclusion

Using articulating antibiotic‐loaded spacers showed benefits for treating infected TKA in selected patients. No infection recurrence was observed during follow‐up.

     

Systematic Review Comparing Static and Articulating Spacers Used for Revision of Infected Total Knee Arthroplasty

The purpose of this systematic review was to compare the outcomes of static to articulating antibiotic spacers used in two-stage revision total knee arthroplasty. 48 reports with a total of 962 articulating spacers (949 patients) and 707 static spacers (688 patients) with a mean 4 year follow-up were identified for this review. Data on clinical function scores, range-of-motion, complications, and re-infection rates were collected on static and articulating spacers. Both groups had similar improvement in Knee Society Scores (83 versus 82 points), however, the articulating spacer groups had significantly higher range-of-motion (100° versus 92°). There was no difference in the re-infection rates, complication rates, or re-operation rates between the two groups. Currently no specific recommendation can be made about the superiority of one type of spacer over the other.     

人工膝关节术后感染的诊断和二期翻修术

目的：对人工膝关节(TKA)术后感染接受二次翻修术的膝关节进行评估。方法：1996年1月～2002年1月实行人工膝关节置换术353膝，其中5个膝关节在术后出现感染，行二期翻修术即一期手术取出原假体，彻底清创，置入抗生素骨水泥间隙垫，术后使用6周以上的敏感抗生素，二期手术作假体翻修术。结果：平均随访2年，无1例翻修的膝关节发生感染或无菌性松动。最近一次随访时平均膝关节功能评分从翻修术前的0分增加到术后的58分(20～100分)，平均膝关节疼痛评分从术前的38分(24～50分)增加到术后的93分(87—100分)。结论：应该尽量采用二期翻修术处理TKA术后感染，以彻底的清除感染灶，使病人获得良好的功能。     

Granuloma debridement and the use of an injectable calcium phosphate bone cement in the treatment of osteolysis in an uncemented total knee replacement

Polyethylene particulate debris-induced periprosthetic osteolysis is a known complication of knee arthroplasty surgery, and may result in the need for revision surgery. The management of these bony defects can be surgically challenging, and full revisions of well-fixed total knee components can lead to substantial bone loss. We present the case of a 71 year old man who developed knee pain and osteolysis around an uncemented total knee replacement. Due to significant medical comorbidies he was treated by percutaneous cyst granuloma debridement and grafting using an injectable calcium phosphate bone substitute. There were no wound complications, and the patient was allowed to fully weight-bear post-operatively. Histopathology and microbiology of the cyst material confirmed polyethylene granulomata without any evidence of infection. At 6 weeks post-operatively the patient's previous knee pain had resolved, he was able to comfortably fully weight-bear. Preoperative scores (Knee Society Score (KSS) 41, WOMAC score 46.2, and Oxford Knee Score 39) had all improved at the 12-month post-operative review KSS 76, WOMAC 81.7 and Oxford Knee score 21). This is a safe and effective technique with minimal morbidity and may be an appropriate treatment modality when more extensive revision surgery is not possible. The case is discussed with reference to the literature.